Is my Diesel Mechanic brilliant or a fool?

[ghockaday]

"Will run forever" is just a figure of speech. We Californians kinda have our own lingo.

We do in VA as well, bless your little heart.

I obviously knew you did not mean to infinity. Its a saying I may apply to a working slow turning farm tractor as oppose to a marine diesel though.

[csoule13]

]
Thanks! I'm also trying to figure out which parts of my experience with gas engines translate to diesel. I'm also pretty neurotic about them. Given the cost, the stakes are very high. It makes me want to micromanage the engine, and is weird to hear that you can't.

An alternate POV, meant in the best possible way - the stakes aren't very high. You (and I, fwiw) are the owners of old sailboats with old engines that we only have a passing guess at how they were used and maintained. Unless you are a better wrench swinger than I am, which isn't a high bar to clear, there's only so much we can do. Use clean fuel, deal with any fuel problems when they arise, change the oil and keep the cooling system in good shape. After that, it's just as much a matter of fate and luck and probabilities.

Yup, if my YSM8 dies tomorrow, I have some choices to make. If I didn't want to be in that position, I wouldn't have purchased a 1978 boat with a 1978 engine.

Short version - there are just some things you sign up for when you buy an old boat. Do your best to handle them, but fretting over maybe needing to do a repower just strikes me as not worth the energy. As a former flying buddy said, you've already bought into the lifestyle of ownership. Everything else is just the cost of staying there.

[fritz3000g]

Unless you are a better wrench swinger than I am, which isn't a high bar to clear, there's only so much we can do. Use clean fuel, deal with any fuel problems when they arise, change the oil and keep the cooling system in good shape. After that, it's just as much a matter of fate and luck and probabilities.

Appreciate the additional POV, and I think that makes sense. I’m not a fretter by nature, and once I learn everything I can about the engine and it proves reliable, I’ll generally stop worrying.
My real hope is to extend the life of the engine long enough that repowering with an electrical motor is cost-effective and proven. I think we’re not too far off.

A diesel will not run forever if it is a saltwater boat that is raw water cooled. My opinion is still that its the environment not the hours.

I’m fortunate that my boat has been in freshwater for 20 years, after spending the previous 20 in saltwater. I’m assuming that after 20 years, whatever damage the salt had done would have made itself known.

As others have pointed out

1. good maintenance
2. clean fuel (no algae or water in the fuel tank that sits too long)
3. clean air
4. good compression
5. oil never getting up to temperature to burn the condensate out of it
6. strainers getting plugged and running hot from time to time.

Thanks! I'll put these on the list.

I own a 1982 CD30 with the raw water cooled Volvo MD7 in it. When I bought the boat in 1996 I had no idea of how many hours were on it. It started and ran ok. Fast forward 5-6 years. I started to see an accumulation of soot on the stern and the starting became more of an issue. When it did start I noticed it would smoke a little. This is a 2 cyl motor and I would hear 1 cyl firing until it got enough fuel into it to fire off the second cyl and then come to life pushing out even more black smoke. It's a sail boat, I lived with it for another 3-4 years. I was fortunate to have access to a compression gage (diesel engines require unique gages for this) from a Volvo certified marine mechanic 1/4 mile from where I worked. When I did finally get around to checking it 2-3 years later I found one cylinder was significantly lower than the other which is why I'd hear 1 cyl firing first. That's when I found a second MD7 and began a complete rebuild (1st over pistons, bearings, rebuilt injectors and high pressure pump) in my garage knowing things don't fix themselves. That motor sat in the garage for another 3-4 years while old smokey got worse. End of season cold starting here in the NE would take 30 to 40 seconds of cranking over. It still ran, I changed it out. I guess my point is old diesels will start and run for a long time.

Great story! I love it! I wonder whether you would have gotten even more years out of it had that low compression piston been rebuilt when symptoms first started.

A day sailing boat with a diesel is hard on them. Better than gas by far. but starting and running 20 minutes to get out the slip, turning it off sailing for the day, starting running 20 minutes to get back in the slip is far harder than running up to temperature for a days work. A lot of wear is when a dry engine is turning over, before oil pressure comes up.
Just my opinion, but diesels are meant to work. The harder that work with proper maintenance, the longer they last. I have know truck drivers that never shut their truck down. (when fuel was cheap) unless it was going to sit for few days.

This brings up an interesting question.

Is it a good idea to warm up your engine before taking it out of the marina? If warming up is good, do you warm up by idling, by running at medium rpms without load, or by running under load?

All I meant was

1. change the oil and filters often (I change the oil every 100 hrs., some do it after 50hrs..
2. change the fuel less often maybe 200-300 hrs. I use one of those pumps that goes on a drill motor to suck the crud out of my fuel tank. I would pull the tank but it's really set in there. It's more work than I want to do right now.
3. I've flushed out my raw water cooling system with a 7:1 ratio of muriatic acid and water several times in the 5 years I ve had this boat
4. I took it all apart and cleaned the exhaust manifold manually and replaced all the old hoses, thermostat and water pump.
5. OH... don't use cheap oil. I use Chevron Delo 400 for diesels

Awesome! I’ll add these items to my list.
Would you change anything about the flush in a freshwater boat?

You can send oil samples to a lab, such as Blackstone, and they will analyze the oil, looking for metal deposits, oil contamination, higher than normal temperatures, etc. the first analysis is often revealing, but annual analysis will pick up trends and help with predictions. When I was flying we used to do this for all engines every 100 hours. For our 27 that would have been every seven years. We did it almost every other year

Fascinating! I’m really curious how often this finds issues that you might not find otherwise.

[JD-MDR]

Wow Fritz! You really are taking notes. Just for fun check out the thread Mystery hole if you want to learn more about the cooling system :https://www.cruisersforum.com/forums/f5 ... 435-2.html

Oh, I forgot you have the Yanmar

[ghockaday]

You can send oil samples to a lab, such as Blackstone, and they will analyze the oil, looking for metal deposits, oil contamination, higher than normal temperatures, etc. the first analysis is often revealing, but annual analysis will pick up trends and help with predictions. When I was flying we used to do this for all engines every 100 hours. For our 27 that would have been every seven years. We did it almost every other year
Fascinating! I’m really curious how often this finds issues that you might not find otherwise.

For someone that frets and wants to be meticulous? This is a no brainer. The oil test can tell wear by the amount of trace metals in the oil, and all sorts of other stuff. Non invasive and easy. Not terrible expensive. I know people with diesel VWs that did them every oil change. I have near 300k on her now and have never done one though.

[Dick Kobayashi]

I had a 25D with a 1GM engine for 20 years. Early on I replaced the head and exhaust elbow (black smoke) but otherwise NEVER did anything but perform diligent annual preventative maintenance. These engines have problems when ancillary elements are not tended to. Dirty fuel, poor filters, air in the fuel line, poor cooling water circulation, lazy starters, loose alternator belts, and on and on. Mostly these are matters the owner can learn to address/recognize. There is very little that will go wrong INSIDE the engine that will not display a symptom long before the engine stops working.

I used to like sailing off my mooring, but in the last few years of ownership when sailing alone I would fire up the engine while I got the sails up so I would be certain that it would start should I need it.

btw the best small addition was a cooling water filter btwn the hull and water pump.

Although it is a common phrase "will run forever" is not literal. These 1GM engines were originally designed as small tractor/farm engines for use in Japanese agriculture. We are using them far fewer hours and in much cleaner conditions. btw GM stands for General Marine.

I think your mechanic and the wise hands on the board have it about right. But the tendency to analogize to gasoline engines coupled with fear of being without power is familiar to many of us.

[Jack.Ducas]

I just finished reading the Cruisers Forum regarding the MD7s, although it's almost 8-9 years old there's alot of good information there. Thank you JD-MDR. I really like those little motors and enjoy reading information about them as well. As for the old motor I replaced (that's down in the garage) as said it still ran when I removed it. I have to believe it would run for many more hours with new pistons and rings, maybe just rings. LOL. I figured that replacement (out and in, about 10 hours) would take much less time compared to dealing with old smokey at that time (maybe some day) besides I really wanted to become intimate with them. I also replaced rod and crank bearings as well as all gaskets. I think I have about $1800 into it. Parts are wicked expensive for those things, 1 piston $250 ouch! if you can even find them here in the USA anymore, I highly doubt it. One thing I should say is when I first got the boat I got in the habit of religiously checking the oil prior to starting. Everyone should do this. 2002-2003 one weekend I changed the oil and filter after warming her up, then ran it for 10 minutes, checked it for leaks then went home. The following weekend prior to starting I pulled the dipstick. MILK!! My MD7s have gear driven water pumps with 2 seals. 1 to keep the oil in, 1 to keep the water out. After rebuilding the pump (impeller, shaft, seals and bearings) change oil and filter, run 20-30 seconds, 4TIMES!! she ran fine for many years. I'll always check the oil before starting.

[fritz3000g]

In talking with the previous owner today, he shared that the boat tops out at 2500 rpms in spring, then as it gets used more is able to operate at 2800 rpms. He said that you can push it to 3000 rpms but he doesn't feel comfortable operating that fast.

The 1GM is rated for 3400 rpms, and meant to be operated at 3000 rpms.

Is either the fact that it runs at lower rpms in spring, or that it can only generate 3000 rpms in summer, a concern?

He also shared that he likes to warm up the engine at idle for a long time when first starting in spring, and for a few minutes at idle when starting each time after that. Is this a good idea?

btw the best small addition was a cooling water filter btwn the hull and water pump.

Do you have a link to the product for this? Would you use it in fresh water or just salt?

I found this one: https://www.amazon.com/Seaflo-Marine-In ... B07C117TVY

I've flushed out my raw water cooling system with a 7:1 ratio of muriatic acid and water several times in the 5 years I ve had this boat

Would you do this in a freshwater boat?

[JD-MDR]

I dont know if flushing with acid would be necessary. I dont think so. At least not so often

[ghockaday]

In talking with the previous owner today, he shared that the boat tops out at 2500 rpms in spring, then as it gets used more is able to operate at 2800 rpms. He said that you can push it to 3000 rpms but he doesn't feel comfortable operating that fast.

The 1GM is rated for 3400 rpms, and meant to be operated at 3000 rpms.

Is either the fact that it runs at lower rpms in spring, or that it can only generate 3000 rpms in summer, a concern?

He also shared that he likes to warm up the engine at idle for a long time when first starting in spring, and for a few minutes at idle when starting each time after that. Is this a good idea?

btw the best small addition was a cooling water filter btwn the hull and water pump.

Do you have a link to the product for this? Would you use it in fresh water or just salt?

I found this one: https://www.amazon.com/Seaflo-Marine-In ... B07C117TVY

I've flushed out my raw water cooling system with a 7:1 ratio of muriatic acid and water several times in the 5 years I ve had this boat

Would you do this in a freshwater boat?

You would if it was getting plugged up with rust. Beware, the one I got (volvo) had be flushed a few times with acid as well to try and dissolve the rust to get better cooling. I ended up with a hole through the cylinder wall. The rust is coming from somewhere.

None of what you described sounds great. It's amazing what people remember to tell you after the sale. May last a long time, may not, I would not fret too much about it at this point.

It could very well be a compression issue, idling in the spring allows the cylinder walls to get good and oily, sealing them up better, Idling every time you start it will allow the same thing. As the engine warms it gets tighter. It will probably smoke pretty bad at first and have a lot of blow back into the crank case. Not being able to get up to full RPM could be a compression issue as well.

[Jerry Hammernik]

My Volvo is rated at 3000 rpms. I don't every push it that far. At 3000 rpm it sounds like the pistons are trying to change cylinders. The previous owner didn't say it wouldn't go to 3000 as I read the quote. Just that he didn't like to run that hard. If it won't climb the revs it can be a matter of prop pitch. If the prop isn't pitched to match the motor it may not reach the rpm goal.

In my humble opinion the fact that the boat has been under power successfully for years is the best evidence of things being ok. Do normal maintenance, oil changes, clean filters, clean fuel and I think you'll be fine.

[ghockaday]

My Volvo is rated at 3000 rpms. I don't every push it that far. At 3000 rpm it sounds like the pistons are trying to change cylinders. The previous owner didn't say it wouldn't go to 3000 as I read the quote. Just that he didn't like to run that hard. If it won't climb the revs it can be a matter of prop pitch. If the prop isn't pitched to match the motor it may not reach the rpm goal.

In my humble opinion the fact that the boat has been under power successfully for years is the best evidence of things being ok. Do normal maintenance, oil changes, clean filters, clean fuel and I think you'll be fine.

"In talking with the previous owner today, he shared that the boat tops out at 2500 rpms in spring, then as it gets used more is able to operate at 2800 rpms. He said that you can push it to 3000 rpms but he doesn't feel comfortable operating that fast."


The previous owner did say it would not run over 2500 RPM in the Spring. Obviously prop pitch does not change. I do agree with you however. Maintain it and run it. It will be the best thing for it. At least till you find out what else he did not tell you. When it doesn't get enough compression to start. Get it rebuilt.

[fritz3000g]

Sounds good. I'm hearing from everyone that reduced max RPMs is a concern, but it's not going to cause other problems and doesn't require immediate action.

At the same time, I don't want to get stuck in a situation where I need the motor to start but it won't. With the boat three hours away, not starting is a pretty big hassle depending on who I've gotten to come along.

So... if I notice any of the following, then that would make me want to perform a leakdown test to determine the cause of the problem:

• Further reduced max rpms
• Difficulty starting (more than a couple of turnovers)
• A bad result from an oil test

At some point I might just purchase my own compression or leak down tester in case I want to keep the boat on a pin rather than next to a marina with a mechanic.

https://www.amazon.com/diesel-compressi ... 3A15684181
https://www.amazon.com/Performance-Tool ... PQCJQ?th=1

[JD-MDR]

Hi Fritz. Do you have a motorized dinghy or inflatable? Twice I've broke down and had to tow myself in, about 15mi each time. I tie it up tight to the stern quarter The 5 hp Nissan moves my boat along at 4 knots at half throttle. Of coarse both times was in zero wind. Other wise I would have sailed in. I have an inverter and use the shop vac to inflate the boat pretty fast. Sometimes I stow it inflated on top of the coach. But not so much anymore. I got a tiny little kayak now so I can get ashore to go hiking. I am mostly single handling so only need the inflatable when I have company or need to haul supplys. I can't believe how little gas I used. 3.5 gal goes about 8 hrs.
Though I trust my inboard I always like to have a backup. I have many neighbors that call "tow boat' everytime they have a problem. Even though its pretty cheap and a good deal I think about $100 yr. I like being self-sufficient. I would be embarrassed if I had to get towed in.

[fritz3000g]

Hi Fritz. Do you have a motorized dinghy or inflatable? Twice I've broke down and had to tow myself in, about 15mi each time. I tie it up tight to the stern quarter The 5 hp Nissan moves my boat along at 4 knots at half throttle.

I do have a dinghy. I've been thinking of attaching a motor mount to the stern as a way to store the dinghy motor. If that could lower the prop into the water then it could be a backup motor. Could also add an extra knot in a rush and provide maneuverability in reverse in tight anchorages.

If I decide I care about the appearance it could be removable.