OK - so much for being concentious. My MD7A has run perfectly since I bought Mariah last May. 6 weeks ago, I replaced the secondary fuel filter (an older Fram) with a new Racor and the primary ( a silver looking can) with one that came with the boat (a Puralator. I bled the system 2-3 times and things seemed OK with the exception that the engne, which used to turn over EVERY TIME within 5-8 seconds, now took 15 to 20 seconds to start. Then, after a week of sitting, I went to take it out to be hauled, and it would not start, just turn over. I bled it again and it started. It ran for about an hour to the yard and sat on blocks for 9 days to do the bottom etc. Went back in the water, and started. Took her home and every 3-4 days, I started it and it started, albeit with the 15-20 second cranking. Saturday we went out and it started 3 times as we sailed and motored. When we got caught in a 15 foot tide change and a strong flood current we needed to go against (of course), it would not start. I bled it twice and when it started, it ran for 3.5 hours to get us home. Now for the questions:
1. Where does the system change from suction to pressure?
Seems to me tot to be a problem on the suction side as you would expect air to get in when the engine is running. It must be on the high pressure side that is pushing air out when running and allowing it back in when stopped. I have seen no leaks in the system anywhere. I suspect the bleed screw, Primary filete seal, or crush washer under the bleed screw to be a problem, but am looking for any advice here. If anyone hase any info or needs any more info to point me in the right direction, I sure would appreciate it.
PS - The current was so strong, it took us 3 hours at full power to go back the same distance it took us 20 minues to drift. Shame on me for not paying better attention.
Thanks.
John Dupras
S/V Mariah
john_dupras@hotmail.com
Diesel Frustration (need explaination..)
Moderator: Jim Walsh
-
Bill Goldsmith
Re: Diesel Frustration (need explaination..)
Just some ideas from another DIY dieseler.........
As far as bleeding is concerned you are right to suspect the crush washer or filter seal. My crush crush washer was causing me problems until I learned (the hard way) that they are one-use only. Did you grease the o-ring on the new filter seal? As with a chain, the fuel system is as weak as its weakest link. You may want to check the fuel hose for any deteriotation or cracking around the hose clamps. If so, replace your fuel hose. Be sure all hose clamps are very snug--air can get in around them. Work from the tank to the engine and see if you can spot where the air is getting in. I'm no diesel expert (I'll leave those comments to others on this board) but I believe the entire user-serviceable system is suction-based. The pressure is added by the injector pump which is not user-serviceable.
As far as the long starting time is concerned, I notice that mine takes longer to start when the temp is lower. I'm actually considering starting a log of outdoor temperature vs cold start time just to document this. The diesel needs to compress the air/fuel mixture to the flash point. If you are starting out with colder air (and have no glow plugs) it will take a few more chugs to get it going.
Bill
OK - so much for being concentious. My MD7A has run perfectly since I bought Mariah last May. 6 weeks ago, I replaced the secondary fuel filter (an older Fram) with a new Racor and the primary ( a silver looking can) with one that came with the boat (a Puralator. I bled the system 2-3 times and things seemed OK with the exception that the engne, which used to turn over EVERY TIME within 5-8 seconds, now took 15 to 20 seconds to start. Then, after a week of sitting, I went to take it out to be hauled, and it would not start, just turn over. I bled it again and it started. It ran for about an hour to the yard and sat on blocks for 9 days to do the bottom etc. Went back in the water, and started. Took her home and every 3-4 days, I started it and it started, albeit with the 15-20 second cranking. Saturday we went out and it started 3 times as we sailed and motored. When we got caught in a 15 foot tide change and a strong flood current we needed to go against (of course), it would not start. I bled it twice and when it started, it ran for 3.5 hours to get us home. Now for the questions:
goldy@bestweb.net
As far as bleeding is concerned you are right to suspect the crush washer or filter seal. My crush crush washer was causing me problems until I learned (the hard way) that they are one-use only. Did you grease the o-ring on the new filter seal? As with a chain, the fuel system is as weak as its weakest link. You may want to check the fuel hose for any deteriotation or cracking around the hose clamps. If so, replace your fuel hose. Be sure all hose clamps are very snug--air can get in around them. Work from the tank to the engine and see if you can spot where the air is getting in. I'm no diesel expert (I'll leave those comments to others on this board) but I believe the entire user-serviceable system is suction-based. The pressure is added by the injector pump which is not user-serviceable.
As far as the long starting time is concerned, I notice that mine takes longer to start when the temp is lower. I'm actually considering starting a log of outdoor temperature vs cold start time just to document this. The diesel needs to compress the air/fuel mixture to the flash point. If you are starting out with colder air (and have no glow plugs) it will take a few more chugs to get it going.
Bill
OK - so much for being concentious. My MD7A has run perfectly since I bought Mariah last May. 6 weeks ago, I replaced the secondary fuel filter (an older Fram) with a new Racor and the primary ( a silver looking can) with one that came with the boat (a Puralator. I bled the system 2-3 times and things seemed OK with the exception that the engne, which used to turn over EVERY TIME within 5-8 seconds, now took 15 to 20 seconds to start. Then, after a week of sitting, I went to take it out to be hauled, and it would not start, just turn over. I bled it again and it started. It ran for about an hour to the yard and sat on blocks for 9 days to do the bottom etc. Went back in the water, and started. Took her home and every 3-4 days, I started it and it started, albeit with the 15-20 second cranking. Saturday we went out and it started 3 times as we sailed and motored. When we got caught in a 15 foot tide change and a strong flood current we needed to go against (of course), it would not start. I bled it twice and when it started, it ran for 3.5 hours to get us home. Now for the questions:
John Dupras wrote: 1. Where does the system change from suction to pressure?
Seems to me tot to be a problem on the suction side as you would expect air to get in when the engine is running. It must be on the high pressure side that is pushing air out when running and allowing it back in when stopped. I have seen no leaks in the system anywhere. I suspect the bleed screw, Primary filete seal, or crush washer under the bleed screw to be a problem, but am looking for any advice here. If anyone hase any info or needs any more info to point me in the right direction, I sure would appreciate it.
PS - The current was so strong, it took us 3 hours at full power to go back the same distance it took us 20 minues to drift. Shame on me for not paying better attention.
Thanks.
John Dupras
S/V Mariah
goldy@bestweb.net
-
Larry DeMers
Re: Diesel Frustration (need explaination..)
Hi Guys,
Having experienced, and triumphed over this very same problem..I mean to say it is the exact same symptom!..I may be able to give you some of my understandings and what has worked for me.
I also have the MD7A/B engine, on a Cd30c. I won't repeat our symptoms except that I was getting it to fire eventually, on one cylinder, then two after perhaps a minute of one lung running.
There are two fuel systems on these diesels..well, three if you count the return line to the tank. The low pressure system consists of the tank pick tube, the hose, the Primary (as in first in line) filter (s), then the engines lift pump with it's screen and finally the secondary engine mounted filter (the silver screw on filter). The high pressure side consists of the injector pump, rigid high pressure tubing, the injectors and the nuts that connect them to the tubing.
We can forget the return system for now.
There are two injector pumps that were fit to this engine..a Bosch displacement type and a CAV type. I am not sure how to identify them, although the engine manual does show the way to do it.
My inj. pump is self-bleeding on the high pressure side. That is air bubbles that are trapped in the tube will get blown past the injector, into the return fuel collector system, and then the tank. This is for air that is trapped in the tubes while it sits idle.
In our cases, after the air was bled through the injector pump (through long start periods), the engine would run without failure. The air was purged from the high pressure side as it ran, but returned when it was turned off and allowed to cool. Cooling does several things, amongst them it changes the clearance of metal parts, including fittings on the high pressure lines. I suggest that a complete and perfect bleed of the low and high pressure sides is needed to eliminate the problems with that. I know that there has been several bleeds done so far, so lets cut to the chase.
Go to the engine mounted silver filter, we called the secondary filter (in front of the engine). Get a hand full of paper towels, and the right size wrench for the drain screw at the top of the filter. Position the towels around the bottom of the filter so that it catches the fuel as it dribbles off the can. Loosen the bleed screw 1/4 turn, while depressing the manual lift pump lever all the way down (if there seems to be less play or action from the lever than usual, rotate the engine flywheel a bit to put the pumps actuating lever on the right part of the driving cam in the engine. The lever should now have a full motion to it. You can rotate the flywheel with the engine in neutral, by lifting the decompression lever and then turning the alternator belt by hand).
Pump the hand pump slowly and deliberately, watching the flow of fuel from the bleed screw on the filter. Fuel should ooze out of the base of the threaded area of the screw. There should be no air bubbles at all in it. **If this is true..there are no air bubbles in the flow**, then pump one more time slowly, while at the same time, slowly close off the bleed screw. You want the bleed screw under positive internal pressure (real small)when it is sealed off, or it can suck air back into the low pressure side. The low pressure side appears ok so far. now for the interesting stuff.
The high pressure side on my inj. pump has only one place to bleed that I have found..at the injector nut. To bleed the high pressure side:
Lift the decompression lever up, and pack the area around the injector of interest with paper towels. Get a light in there to help see the fuel with (should have one mounted in the engine compartment anyway..). have a friend help by turning the engine key on command from you. Crack the injector nut free a bit, then turn over the engine and watch what the fuel looks like coming out. When it appears that no air bubbles are in the fuel stream, tighten down the injector nut to the specified torque..or thereabouts. Repeat this with the other injector.
I might add that the throttle lever should be around half way during the bleeding exercise.
***Now a note of caution here***
As you turn the engine over with the compression lever either engaged or not, the engine will be pumping water into tthe waterlift muffler. With no exhaust present to propel the water out the tailpipe, it has no place to go. Eventually, that thing will fill and feed back into your engines exhaust ports..spoiling your year. Do not do this.
I recommend that you take out the impellor or remove the drain plug from the mufflers bottom, so that the water can either be prevented from being pumped into the muffler, or it can be drained from the muffler before it gets too high.Pay attention to this one folks, as this will happen if you don't.
If the low pressure side showed to be clear of bubbles, then I would bet that the problem is in the fittings or compression nut for the high pressure side. It is an awfully common problem, and so anything you find out, would you please feed it back to us so that we can learn more about this problem.
Oh, you asked where the system changed from suction to pressure. It is at the entrance to the lift pump. The pressures are very small.. .7psi is common. But the lift pump will push the fuel into the high pressure pump, which compresses it to give something like 800 psi on it's output.
I hope this epistle helped a bit.
Good Luck!
Larry DeMers
s/v DeLaMer
Cape Dory 30
demers@sgi.com
Having experienced, and triumphed over this very same problem..I mean to say it is the exact same symptom!..I may be able to give you some of my understandings and what has worked for me.
I also have the MD7A/B engine, on a Cd30c. I won't repeat our symptoms except that I was getting it to fire eventually, on one cylinder, then two after perhaps a minute of one lung running.
There are two fuel systems on these diesels..well, three if you count the return line to the tank. The low pressure system consists of the tank pick tube, the hose, the Primary (as in first in line) filter (s), then the engines lift pump with it's screen and finally the secondary engine mounted filter (the silver screw on filter). The high pressure side consists of the injector pump, rigid high pressure tubing, the injectors and the nuts that connect them to the tubing.
We can forget the return system for now.
There are two injector pumps that were fit to this engine..a Bosch displacement type and a CAV type. I am not sure how to identify them, although the engine manual does show the way to do it.
My inj. pump is self-bleeding on the high pressure side. That is air bubbles that are trapped in the tube will get blown past the injector, into the return fuel collector system, and then the tank. This is for air that is trapped in the tubes while it sits idle.
In our cases, after the air was bled through the injector pump (through long start periods), the engine would run without failure. The air was purged from the high pressure side as it ran, but returned when it was turned off and allowed to cool. Cooling does several things, amongst them it changes the clearance of metal parts, including fittings on the high pressure lines. I suggest that a complete and perfect bleed of the low and high pressure sides is needed to eliminate the problems with that. I know that there has been several bleeds done so far, so lets cut to the chase.
Go to the engine mounted silver filter, we called the secondary filter (in front of the engine). Get a hand full of paper towels, and the right size wrench for the drain screw at the top of the filter. Position the towels around the bottom of the filter so that it catches the fuel as it dribbles off the can. Loosen the bleed screw 1/4 turn, while depressing the manual lift pump lever all the way down (if there seems to be less play or action from the lever than usual, rotate the engine flywheel a bit to put the pumps actuating lever on the right part of the driving cam in the engine. The lever should now have a full motion to it. You can rotate the flywheel with the engine in neutral, by lifting the decompression lever and then turning the alternator belt by hand).
Pump the hand pump slowly and deliberately, watching the flow of fuel from the bleed screw on the filter. Fuel should ooze out of the base of the threaded area of the screw. There should be no air bubbles at all in it. **If this is true..there are no air bubbles in the flow**, then pump one more time slowly, while at the same time, slowly close off the bleed screw. You want the bleed screw under positive internal pressure (real small)when it is sealed off, or it can suck air back into the low pressure side. The low pressure side appears ok so far. now for the interesting stuff.
The high pressure side on my inj. pump has only one place to bleed that I have found..at the injector nut. To bleed the high pressure side:
Lift the decompression lever up, and pack the area around the injector of interest with paper towels. Get a light in there to help see the fuel with (should have one mounted in the engine compartment anyway..). have a friend help by turning the engine key on command from you. Crack the injector nut free a bit, then turn over the engine and watch what the fuel looks like coming out. When it appears that no air bubbles are in the fuel stream, tighten down the injector nut to the specified torque..or thereabouts. Repeat this with the other injector.
I might add that the throttle lever should be around half way during the bleeding exercise.
***Now a note of caution here***
As you turn the engine over with the compression lever either engaged or not, the engine will be pumping water into tthe waterlift muffler. With no exhaust present to propel the water out the tailpipe, it has no place to go. Eventually, that thing will fill and feed back into your engines exhaust ports..spoiling your year. Do not do this.
I recommend that you take out the impellor or remove the drain plug from the mufflers bottom, so that the water can either be prevented from being pumped into the muffler, or it can be drained from the muffler before it gets too high.Pay attention to this one folks, as this will happen if you don't.
If the low pressure side showed to be clear of bubbles, then I would bet that the problem is in the fittings or compression nut for the high pressure side. It is an awfully common problem, and so anything you find out, would you please feed it back to us so that we can learn more about this problem.
Oh, you asked where the system changed from suction to pressure. It is at the entrance to the lift pump. The pressures are very small.. .7psi is common. But the lift pump will push the fuel into the high pressure pump, which compresses it to give something like 800 psi on it's output.
I hope this epistle helped a bit.
Good Luck!
Larry DeMers
s/v DeLaMer
Cape Dory 30
John Dupras wrote: OK - so much for being concentious. My MD7A has run perfectly since I bought Mariah last May. 6 weeks ago, I replaced the secondary fuel filter (an older Fram) with a new Racor and the primary ( a silver looking can) with one that came with the boat (a Puralator. I bled the system 2-3 times and things seemed OK with the exception that the engne, which used to turn over EVERY TIME within 5-8 seconds, now took 15 to 20 seconds to start. Then, after a week of sitting, I went to take it out to be hauled, and it would not start, just turn over. I bled it again and it started. It ran for about an hour to the yard and sat on blocks for 9 days to do the bottom etc. Went back in the water, and started. Took her home and every 3-4 days, I started it and it started, albeit with the 15-20 second cranking. Saturday we went out and it started 3 times as we sailed and motored. When we got caught in a 15 foot tide change and a strong flood current we needed to go against (of course), it would not start. I bled it twice and when it started, it ran for 3.5 hours to get us home. Now for the questions:
1. Where does the system change from suction to pressure?
Seems to me tot to be a problem on the suction side as you would expect air to get in when the engine is running. It must be on the high pressure side that is pushing air out when running and allowing it back in when stopped. I have seen no leaks in the system anywhere. I suspect the bleed screw, Primary filete seal, or crush washer under the bleed screw to be a problem, but am looking for any advice here. If anyone hase any info or needs any more info to point me in the right direction, I sure would appreciate it.
PS - The current was so strong, it took us 3 hours at full power to go back the same distance it took us 20 minues to drift. Shame on me for not paying better attention.
Thanks.
John Dupras
S/V Mariah
demers@sgi.com
-
John Dupras
Re: Diesel Frustration (need explaination..)
OK Larry That helps. Part of the problem seems to be that when I go to bleed the system after it fails to start, there are bubbles in the secondary filter bleed. The couple of times I checked at the front injector, there was no fuel. Is there a crush washer under that banjo fitting that might be damaged? Is it posssible that the darn thing has been running on one cylinder all along? I have the CAV system on mine with 2 "wing nut" type fittings and a 3rd bolt type that the manual identifies as the second bleed screw, but all I have ever gotten out of it is a hiss when I open it after bleeding the secondary and cranking the engine. I figured no problem in the suction side, i.e. up tp the lift pump, as when it runs, it continues to run. By the way, do they make a bleed screw that goes on with a wrench? Mine is a straight slot and it needs to be REALLY torqued down to not leak. Crush washer? I WILL figure this out, but boy, it can be frustrating. Thanks for the info.
John
S/V Mariah
john_dupras@hotmail.com
John
S/V Mariah
Larry DeMers wrote: Hi Guys,
Having experienced, and triumphed over this very same problem..I mean to say it is the exact same symptom!..I may be able to give you some of my understandings and what has worked for me.
I also have the MD7A/B engine, on a Cd30c. I won't repeat our symptoms except that I was getting it to fire eventually, on one cylinder, then two after perhaps a minute of one lung running.
There are two fuel systems on these diesels..well, three if you count the return line to the tank. The low pressure system consists of the tank pick tube, the hose, the Primary (as in first in line) filter (s), then the engines lift pump with it's screen and finally the secondary engine mounted filter (the silver screw on filter). The high pressure side consists of the injector pump, rigid high pressure tubing, the injectors and the nuts that connect them to the tubing.
We can forget the return system for now.
There are two injector pumps that were fit to this engine..a Bosch displacement type and a CAV type. I am not sure how to identify them, although the engine manual does show the way to do it.
My inj. pump is self-bleeding on the high pressure side. That is air bubbles that are trapped in the tube will get blown past the injector, into the return fuel collector system, and then the tank. This is for air that is trapped in the tubes while it sits idle.
In our cases, after the air was bled through the injector pump (through long start periods), the engine would run without failure. The air was purged from the high pressure side as it ran, but returned when it was turned off and allowed to cool. Cooling does several things, amongst them it changes the clearance of metal parts, including fittings on the high pressure lines. I suggest that a complete and perfect bleed of the low and high pressure sides is needed to eliminate the problems with that. I know that there has been several bleeds done so far, so lets cut to the chase.
Go to the engine mounted silver filter, we called the secondary filter (in front of the engine). Get a hand full of paper towels, and the right size wrench for the drain screw at the top of the filter. Position the towels around the bottom of the filter so that it catches the fuel as it dribbles off the can. Loosen the bleed screw 1/4 turn, while depressing the manual lift pump lever all the way down (if there seems to be less play or action from the lever than usual, rotate the engine flywheel a bit to put the pumps actuating lever on the right part of the driving cam in the engine. The lever should now have a full motion to it. You can rotate the flywheel with the engine in neutral, by lifting the decompression lever and then turning the alternator belt by hand).
Pump the hand pump slowly and deliberately, watching the flow of fuel from the bleed screw on the filter. Fuel should ooze out of the base of the threaded area of the screw. There should be no air bubbles at all in it. **If this is true..there are no air bubbles in the flow**, then pump one more time slowly, while at the same time, slowly close off the bleed screw. You want the bleed screw under positive internal pressure (real small)when it is sealed off, or it can suck air back into the low pressure side. The low pressure side appears ok so far. now for the interesting stuff.
The high pressure side on my inj. pump has only one place to bleed that I have found..at the injector nut. To bleed the high pressure side:
Lift the decompression lever up, and pack the area around the injector of interest with paper towels. Get a light in there to help see the fuel with (should have one mounted in the engine compartment anyway..). have a friend help by turning the engine key on command from you. Crack the injector nut free a bit, then turn over the engine and watch what the fuel looks like coming out. When it appears that no air bubbles are in the fuel stream, tighten down the injector nut to the specified torque..or thereabouts. Repeat this with the other injector.
I might add that the throttle lever should be around half way during the bleeding exercise.
***Now a note of caution here***
As you turn the engine over with the compression lever either engaged or not, the engine will be pumping water into tthe waterlift muffler. With no exhaust present to propel the water out the tailpipe, it has no place to go. Eventually, that thing will fill and feed back into your engines exhaust ports..spoiling your year. Do not do this.
I recommend that you take out the impellor or remove the drain plug from the mufflers bottom, so that the water can either be prevented from being pumped into the muffler, or it can be drained from the muffler before it gets too high.Pay attention to this one folks, as this will happen if you don't.
If the low pressure side showed to be clear of bubbles, then I would bet that the problem is in the fittings or compression nut for the high pressure side. It is an awfully common problem, and so anything you find out, would you please feed it back to us so that we can learn more about this problem.
Oh, you asked where the system changed from suction to pressure. It is at the entrance to the lift pump. The pressures are very small.. .7psi is common. But the lift pump will push the fuel into the high pressure pump, which compresses it to give something like 800 psi on it's output.
I hope this epistle helped a bit.
Good Luck!
Larry DeMers
s/v DeLaMer
Cape Dory 30
John Dupras wrote: OK - so much for being concentious. My MD7A has run perfectly since I bought Mariah last May. 6 weeks ago, I replaced the secondary fuel filter (an older Fram) with a new Racor and the primary ( a silver looking can) with one that came with the boat (a Puralator. I bled the system 2-3 times and things seemed OK with the exception that the engne, which used to turn over EVERY TIME within 5-8 seconds, now took 15 to 20 seconds to start. Then, after a week of sitting, I went to take it out to be hauled, and it would not start, just turn over. I bled it again and it started. It ran for about an hour to the yard and sat on blocks for 9 days to do the bottom etc. Went back in the water, and started. Took her home and every 3-4 days, I started it and it started, albeit with the 15-20 second cranking. Saturday we went out and it started 3 times as we sailed and motored. When we got caught in a 15 foot tide change and a strong flood current we needed to go against (of course), it would not start. I bled it twice and when it started, it ran for 3.5 hours to get us home. Now for the questions:
1. Where does the system change from suction to pressure?
Seems to me tot to be a problem on the suction side as you would expect air to get in when the engine is running. It must be on the high pressure side that is pushing air out when running and allowing it back in when stopped. I have seen no leaks in the system anywhere. I suspect the bleed screw, Primary filete seal, or crush washer under the bleed screw to be a problem, but am looking for any advice here. If anyone hase any info or needs any more info to point me in the right direction, I sure would appreciate it.
PS - The current was so strong, it took us 3 hours at full power to go back the same distance it took us 20 minues to drift. Shame on me for not paying better attention.
Thanks.
John Dupras
S/V Mariah
john_dupras@hotmail.com
-
Ben Thomas
Re: Diesel Frustration (need explaination..)
John, I had similar problems with my md7a you might look in archives 04/19/2000 amp and fuel saga for milagro a brief description of my problems and fixes. fuel pump and fuel line from tank to racor(1st) filter. new crushables a must. I ended up doing a final bleed on system with engine running. full throttle, be careful and open injector nuts just a fraction maybe 1/4 turn max. one at a time, engine will decrease rpms. then cover with paper towel or shop rag as fuel under pressure is really under pressure and can penetrate skin in a blink of an eye.major health hazard. this really blew everything out of lines. and increased engine rpms. without load engine at full throttle will max at 2800 rpms. good luck, benJohn Dupras wrote: OK - so much for being concentious. My MD7A has run perfectly since I bought Mariah last May. 6 weeks ago, I replaced the secondary fuel filter (an older Fram) with a new Racor and the primary ( a silver looking can) with one that came with the boat (a Puralator. I bled the system 2-3 times and things seemed OK with the exception that the engne, which used to turn over EVERY TIME within 5-8 seconds, now took 15 to 20 seconds to start. Then, after a week of sitting, I went to take it out to be hauled, and it would not start, just turn over. I bled it again and it started. It ran for about an hour to the yard and sat on blocks for 9 days to do the bottom etc. Went back in the water, and started. Took her home and every 3-4 days, I started it and it started, albeit with the 15-20 second cranking. Saturday we went out and it started 3 times as we sailed and motored. When we got caught in a 15 foot tide change and a strong flood current we needed to go against (of course), it would not start. I bled it twice and when it started, it ran for 3.5 hours to get us home. Now for the questions:
1. Where does the system change from suction to pressure?
Seems to me tot to be a problem on the suction side as you would expect air to get in when the engine is running. It must be on the high pressure side that is pushing air out when running and allowing it back in when stopped. I have seen no leaks in the system anywhere. I suspect the bleed screw, Primary filete seal, or crush washer under the bleed screw to be a problem, but am looking for any advice here. If anyone hase any info or needs any more info to point me in the right direction, I sure would appreciate it.
PS - The current was so strong, it took us 3 hours at full power to go back the same distance it took us 20 minues to drift. Shame on me for not paying better attention.
Thanks.
John Dupras
S/V Mariah
btlandscapers@imagina.com
-
Tom
Re: Diesel Frustration (need explaination..)
John, I don't have your engine so can't be specific, but here's an idea that might help. Rig up a coffee can with a plastic through hull in the bottom with a hose barb fitting. You can break into feed line somewhere perhaps at the injector pump. Put some diesel in the coffee can and hang it up higher than the engine so you have a gravity feed. If the engine still won't run, your problem is somewhere after the injector pump perhaps at the injectors. If it runs OK from the coffee can then your problem is in the feed line to the injector pump somewhere. You can work your way back, fitting by fitting until you figure out where the problem is. Once you've isolated the spot where the problem begins you can concentrate on that. When you're done don't through the coffee can away. It's an emergency fuel supply when a hose breaks some dark night or the filters pack up when you're almost home but need to run another 30 minutes to get inside the breakwater. All problems can be solved unless the laws of physics are suspended on your boat -- as a mechanic once told me. As others have said let us all know when you get it solved.John Dupras wrote: OK - so much for being concentious. My MD7A has run perfectly since I bought Mariah last May. 6 weeks ago, I replaced the secondary fuel filter (an older Fram) with a new Racor and the primary ( a silver looking can) with one that came with the boat (a Puralator. I bled the system 2-3 times and things seemed OK with the exception that the engne, which used to turn over EVERY TIME within 5-8 seconds, now took 15 to 20 seconds to start. Then, after a week of sitting, I went to take it out to be hauled, and it would not start, just turn over. I bled it again and it started. It ran for about an hour to the yard and sat on blocks for 9 days to do the bottom etc. Went back in the water, and started. Took her home and every 3-4 days, I started it and it started, albeit with the 15-20 second cranking. Saturday we went out and it started 3 times as we sailed and motored. When we got caught in a 15 foot tide change and a strong flood current we needed to go against (of course), it would not start. I bled it twice and when it started, it ran for 3.5 hours to get us home. Now for the questions:
1. Where does the system change from suction to pressure?
Seems to me tot to be a problem on the suction side as you would expect air to get in when the engine is running. It must be on the high pressure side that is pushing air out when running and allowing it back in when stopped. I have seen no leaks in the system anywhere. I suspect the bleed screw, Primary filete seal, or crush washer under the bleed screw to be a problem, but am looking for any advice here. If anyone hase any info or needs any more info to point me in the right direction, I sure would appreciate it.
PS - The current was so strong, it took us 3 hours at full power to go back the same distance it took us 20 minues to drift. Shame on me for not paying better attention.
Thanks.
John Dupras
S/V Mariah
TomCambria@mindspring.com
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john churchill
a hand surgeon's dream
this is really a bad idea to bleed the system while running. the high pressure side is like 1000 psi or more. if you get your hand anywhere near the spray, you will be injected with diesel which is very toxic to tissues. the hand surgeon however will love you. he will need to do so much operating on you that he'll be able to call andy and order that new robinhood 36. i know as i am an orthopedic surgeon and have seen this type of injury. it is really ugly.
john churchill
john churchill
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Scott Ritchey
Re: Diesel Frustration (need explaination..)
John
The fact you get bubbles from the "engine-mounted" filter (just down stream of the lift pump) indicates you are sucking air somewhere between the tank and the lift pump. Since there is virtually no presure in this section,it's easy to suck air but not notice any diesel leaking. Given that you worked on several hose and and maybe pipe connections in this area, look for a leak there (i.e. check the last thing changed before problem started).
Also, John Churchill is spot on. The high pressure side can be thousands of PSI (my Yanmar YSM book shows 2200 PSI to open the injector). This can be VERY dangerous to the skin.
The fact you get bubbles from the "engine-mounted" filter (just down stream of the lift pump) indicates you are sucking air somewhere between the tank and the lift pump. Since there is virtually no presure in this section,it's easy to suck air but not notice any diesel leaking. Given that you worked on several hose and and maybe pipe connections in this area, look for a leak there (i.e. check the last thing changed before problem started).
Also, John Churchill is spot on. The high pressure side can be thousands of PSI (my Yanmar YSM book shows 2200 PSI to open the injector). This can be VERY dangerous to the skin.
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Larry DeMers
Re: a hand surgeon's dream
Oh come on now, lets not get melodramatic John. I and every mechanic I have ever seen bleeds the diesel this way. The manual describes this practice precisely. There are no other high pressure bleed points on my pump in fact. Lastly,I have 10 years experience with my MD7B, doing all of it's maintenance, including a complete rebuild 4 years ago (admittedly with a mechanics advise and help, and occasional beer).
Don't forget that the fuel, while at a pressure of around 800 psi..not 1000's (on the MD7A/B), is produced through an exceedingly small hole in the injector tip. When you loosen the nut on the injector for bleeding purposes, the leak you create is so much larger than the hole in the tip, it is doubtful if there is even 10 psi present. You most certainly will not damage your hand, or in fact tear a paper towel with the pressure.
Have you ever done this procedure? It is not dangerous..not even close. Imagine if you will, what happens when you take your garden hose, and turn the nozzle down to a fine pinpoint spray. Pass your hand in front of the spray, and you will feel the pressure because it is concentrated on a very small area. Open the valve to spread out the spray, and now that sensation of pressure is gone. The same thing happens with the injectors. Provide a pump that can put out 100's of psi, but a small volume only. Provide an injector that has a very small tip orifice and turn the pump on..the spray will be under a lot of pressure and allow operation of the injectors popit valve which snaps on and off for a cleaner burn cycle (no after-pulse dribble from the tip which forms carbon and smoke, poor power etc.). But now cut the injector fuel line (high pressure side), and the fuel will not spurt out like it did with the injector tip, but rather it will just dribble out of the cut tube, as there is no restriction to build up the pressure.
This is what cracking the injector nuts does..it creates a low resistance path for the fuel to follow, allowing a faster clearing of the air from the system. So no, you positively will not hurt your fingers or hand bleeding the injectors this way. That is just someones imagined worry coming through.
I don't think I would advise using full throttle without a load on the engine,(as someone suggested doing) but certainly 1/2 throttle would be fine. Your engines rpm governor should be set at 2600 rpms max by the way. 2800 rpm is too high, and the valves will tend to start to float at that point. The springs cannot return the valves to their seats fast enough to allow that rpm. This results in burned seats and eventually a top end rebuild.
Cheers!
Larry DeMers
s/v DeLaMer
Cape Dory 30 Sailing Lake Superior
demers@sgi.com
Don't forget that the fuel, while at a pressure of around 800 psi..not 1000's (on the MD7A/B), is produced through an exceedingly small hole in the injector tip. When you loosen the nut on the injector for bleeding purposes, the leak you create is so much larger than the hole in the tip, it is doubtful if there is even 10 psi present. You most certainly will not damage your hand, or in fact tear a paper towel with the pressure.
Have you ever done this procedure? It is not dangerous..not even close. Imagine if you will, what happens when you take your garden hose, and turn the nozzle down to a fine pinpoint spray. Pass your hand in front of the spray, and you will feel the pressure because it is concentrated on a very small area. Open the valve to spread out the spray, and now that sensation of pressure is gone. The same thing happens with the injectors. Provide a pump that can put out 100's of psi, but a small volume only. Provide an injector that has a very small tip orifice and turn the pump on..the spray will be under a lot of pressure and allow operation of the injectors popit valve which snaps on and off for a cleaner burn cycle (no after-pulse dribble from the tip which forms carbon and smoke, poor power etc.). But now cut the injector fuel line (high pressure side), and the fuel will not spurt out like it did with the injector tip, but rather it will just dribble out of the cut tube, as there is no restriction to build up the pressure.
This is what cracking the injector nuts does..it creates a low resistance path for the fuel to follow, allowing a faster clearing of the air from the system. So no, you positively will not hurt your fingers or hand bleeding the injectors this way. That is just someones imagined worry coming through.
I don't think I would advise using full throttle without a load on the engine,(as someone suggested doing) but certainly 1/2 throttle would be fine. Your engines rpm governor should be set at 2600 rpms max by the way. 2800 rpm is too high, and the valves will tend to start to float at that point. The springs cannot return the valves to their seats fast enough to allow that rpm. This results in burned seats and eventually a top end rebuild.
Cheers!
Larry DeMers
s/v DeLaMer
Cape Dory 30 Sailing Lake Superior
john churchill wrote: this is really a bad idea to bleed the system while running. the high pressure side is like 1000 psi or more. if you get your hand anywhere near the spray, you will be injected with diesel which is very toxic to tissues. the hand surgeon however will love you. he will need to do so much operating on you that he'll be able to call andy and order that new robinhood 36. i know as i am an orthopedic surgeon and have seen this type of injury. it is really ugly.
john churchill
demers@sgi.com
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Larry DeMers
Re: Diesel Frustration (need explaination..)
Scott,
NO it is not dangerous to the skin unless you took the injector out, held it against your hand and operated it.
When the injector nut is cracked open, you create a low resistance path that drains the fuel and air out..it is barely under 10 lbs pressure at that point. To develope the pressure that the popit valves need in the injector, the flow must be restricted to a very small orifice..the injector tip. But short circuit that flow with a low resistance pathway, and the pressure drops to nothing. So don't worry about that..it is not a problem. This is the only way to bleed the high pressure side of my MD7B by the way. It has no other bleed points ont he high pressure side. The procedure of cracking the inj. nut is well documented and used by mechanics world wide.
Cheers!
Larry DeMers
s/v DeLaMer
Cape Dory 30 Sailing Lake Superior
demers@sgi.com
NO it is not dangerous to the skin unless you took the injector out, held it against your hand and operated it.
When the injector nut is cracked open, you create a low resistance path that drains the fuel and air out..it is barely under 10 lbs pressure at that point. To develope the pressure that the popit valves need in the injector, the flow must be restricted to a very small orifice..the injector tip. But short circuit that flow with a low resistance pathway, and the pressure drops to nothing. So don't worry about that..it is not a problem. This is the only way to bleed the high pressure side of my MD7B by the way. It has no other bleed points ont he high pressure side. The procedure of cracking the inj. nut is well documented and used by mechanics world wide.
Cheers!
Larry DeMers
s/v DeLaMer
Cape Dory 30 Sailing Lake Superior
Scott Ritchey wrote: John
The fact you get bubbles from the "engine-mounted" filter (just down stream of the lift pump) indicates you are sucking air somewhere between the tank and the lift pump. Since there is virtually no presure in this section,it's easy to suck air but not notice any diesel leaking. Given that you worked on several hose and and maybe pipe connections in this area, look for a leak there (i.e. check the last thing changed before problem started).
Also, John Churchill is spot on. The high pressure side can be thousands of PSI (my Yanmar YSM book shows 2200 PSI to open the injector). This can be VERY dangerous to the skin.
demers@sgi.com
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Ben Thomas
Re: Diesel Frustration (need explaination..)
Larry thanks for the broader view of experience. I tend to focus into a narrow slot when problem solving and stay that track until resolution always seems that resolution appears when you pop up for that bigger vista. Have had engine at 2800rpms only twice for short periods after bleeding. your analogies are quite grounding. enjoy your summer. best regards benLarry DeMers wrote: Scott,
NO it is not dangerous to the skin unless you took the injector out, held it against your hand and operated it.
When the injector nut is cracked open, you create a low resistance path that drains the fuel and air out..it is barely under 10 lbs pressure at that point. To develope the pressure that the popit valves need in the injector, the flow must be restricted to a very small orifice..the injector tip. But short circuit that flow with a low resistance pathway, and the pressure drops to nothing. So don't worry about that..it is not a problem. This is the only way to bleed the high pressure side of my MD7B by the way. It has no other bleed points ont he high pressure side. The procedure of cracking the inj. nut is well documented and used by mechanics world wide.
Cheers!
Larry DeMers
s/v DeLaMer
Cape Dory 30 Sailing Lake Superior
Scott Ritchey wrote: John
The fact you get bubbles from the "engine-mounted" filter (just down stream of the lift pump) indicates you are sucking air somewhere between the tank and the lift pump. Since there is virtually no presure in this section,it's easy to suck air but not notice any diesel leaking. Given that you worked on several hose and and maybe pipe connections in this area, look for a leak there (i.e. check the last thing changed before problem started).
Also, John Churchill is spot on. The high pressure side can be thousands of PSI (my Yanmar YSM book shows 2200 PSI to open the injector). This can be VERY dangerous to the skin.
btlandscapers@imagina.com
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Olli Wendelin
Re: a hand surgeon's dream
I have heard of this type of injury happening in a diesel shop while rebuilding fuel injectors. While testing injectors someone would get there hand in the way of the spray from the injector.
My YSB12 engine is not self bleeding. I must crack open the nut on the high pressure line at the injector to bleed the line. I agree that this will not create this type of spray when the nut is cracked open prior to cranking the engine.
I did see this type of injury once. A buddy was cutting concrete on a dock piling (underwater) and passed his finger in front of the hydroblaster. This is 18000 psi max but I think they were running at half that. It cut to the bone and injected river water. He ended up in the hospital for a week. The biggest problem ended up being infection.
Olli Wendelin
BLUE MOON
Charleston, SC
wendelin@spawar.navy.mil
My YSB12 engine is not self bleeding. I must crack open the nut on the high pressure line at the injector to bleed the line. I agree that this will not create this type of spray when the nut is cracked open prior to cranking the engine.
I did see this type of injury once. A buddy was cutting concrete on a dock piling (underwater) and passed his finger in front of the hydroblaster. This is 18000 psi max but I think they were running at half that. It cut to the bone and injected river water. He ended up in the hospital for a week. The biggest problem ended up being infection.
Olli Wendelin
BLUE MOON
Charleston, SC
wendelin@spawar.navy.mil
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M.R. Bober
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wayne grenier
Re: Diesel Frustration (need explaination..)
Man-those volvo diesels are fun aren't they-I spent so much time under the lockers last year after changing the fuel tanks and lines I was considering geting my mail sent there-2 items allready pointed out-if you only changed the filter then assume that's where your problem is-allways coat the filter gaskets liberally with motor oil-really soak them and its allways a good idea to change the washer at whatever fitting you loosened-i assume there is under the bleed screw (or an O ring) if you don't want or can't get volvo replavement parts-I have had good luck with the copper fuel line washers they sell at auto spped shops or ) rings from a plumbing supply store-buy more than what you need for future reference-even the mechanics have trouble with these motors-just keep trying-and do one thing at a time-good luck-
grenier@ma.ultranet.com
Scott Ritchey wrote: John
The fact you get bubbles from the "engine-mounted" filter (just down stream of the lift pump) indicates you are sucking air somewhere between the tank and the lift pump. Since there is virtually no presure in this section,it's easy to suck air but not notice any diesel leaking. Given that you worked on several hose and and maybe pipe connections in this area, look for a leak there (i.e. check the last thing changed before problem started).
Also, John Churchill is spot on. The high pressure side can be thousands of PSI (my Yanmar YSM book shows 2200 PSI to open the injector). This can be VERY dangerous to the skin.
grenier@ma.ultranet.com
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sloopjohnl
Re: Diesel Frustration (need explaination..)
john,
are you filling the filters before installing? this will usually save the necessity of bleeding down the system and if you have a self-bleeding system it should almost eliminate bleeding.
are you filling the filters before installing? this will usually save the necessity of bleeding down the system and if you have a self-bleeding system it should almost eliminate bleeding.
John Dupras wrote: OK - so much for being concentious. My MD7A has run perfectly since I bought Mariah last May. 6 weeks ago, I replaced the secondary fuel filter (an older Fram) with a new Racor and the primary ( a silver looking can) with one that came with the boat (a Puralator. I bled the system 2-3 times and things seemed OK with the exception that the engne, which used to turn over EVERY TIME within 5-8 seconds, now took 15 to 20 seconds to start. Then, after a week of sitting, I went to take it out to be hauled, and it would not start, just turn over. I bled it again and it started. It ran for about an hour to the yard and sat on blocks for 9 days to do the bottom etc. Went back in the water, and started. Took her home and every 3-4 days, I started it and it started, albeit with the 15-20 second cranking. Saturday we went out and it started 3 times as we sailed and motored. When we got caught in a 15 foot tide change and a strong flood current we needed to go against (of course), it would not start. I bled it twice and when it started, it ran for 3.5 hours to get us home. Now for the questions:
1. Where does the system change from suction to pressure?
Seems to me tot to be a problem on the suction side as you would expect air to get in when the engine is running. It must be on the high pressure side that is pushing air out when running and allowing it back in when stopped. I have seen no leaks in the system anywhere. I suspect the bleed screw, Primary filete seal, or crush washer under the bleed screw to be a problem, but am looking for any advice here. If anyone hase any info or needs any more info to point me in the right direction, I sure would appreciate it.
PS - The current was so strong, it took us 3 hours at full power to go back the same distance it took us 20 minues to drift. Shame on me for not paying better attention.
Thanks.
John Dupras
S/V Mariah