MD7A Seems to Have Lost Some Power Over the Years

[Pete]

I've owned a 1981 CD30 w/ an MD7A for 5 seasons now. The MD7A seems to have lost some power over the years and is not pushing the boat like it used to. Maintenence consists of changing the oil, oil filter and fuel filters. Is there anything else I should be doing? Any thoughts or suggestions?



peter@zwiefelhofer.com

[Larry DeMers]

Pete,

I would think that loss of power would also be accompanied by a harder time starting if there was a compression problem, and an increase in fuel consumption too. Notice any of these characteristics?

Did anything change during this time -that you would be aware of? Different fuel? Does the engine sound the same as before?

If no to all of these, then I would probably do a very thorough check of the drive train, from prop and shaft up through to the engine. See if anything is loose, or not right there. After you eliminate these, then I guess I would be thinking of a wet compression test for the engine. This will tell you if the compression is in spec. and balanced between the two cylinders. If that is ok, then try completely new fuel. If the fuel is old, it has lost some of the volitiles that were built into the fuel originally. New fuel will restore the old power if the problem was fuel related.

Essentially, you will need to eliminate everything it possibly could be, until the problem is uncovered. It could be the spray pattern of the injectors, which can be tested and rebuilt and re-adjusted for ~$100.

Good Luck!

Larry DeMers
s/v DeLaMer
Cape Dory 30

I've owned a 1981 CD30 w/ an MD7A for 5 seasons now. The MD7A seems to have lost some power over the years and is not pushing the boat like it used to. Maintenence consists of changing the oil, oil filter and fuel filters. Is there anything else I should be doing? Any thoughts or suggestions?

demers@sgi.com

[Jerry]

You should also consider removing the injector bodys and take them to a diesel shop to have them checked for proper pressure settings and proper spray patterns.

I've owned a 1981 CD30 w/ an MD7A for 5 seasons now. The MD7A seems to have lost some power over the years and is not pushing the boat like it used to. Maintenence consists of changing the oil, oil filter and fuel filters. Is there anything else I should be doing? Any thoughts or suggestions?

jlecocq@milehigh.net

[Pete]

I have a 20 gallon fuel tank and typically use less than half of that each season, so the fuel is old (but I do put in stabilizers and biocide). Also, unless it's a hot summer day or the engine is already warm, it the engine won't start unless I use ether or a hair dryer to blow hot air into the air intake.



peter@zwiefelhofer.com

[grenier]

I've owned a 1981 CD30 w/ an MD7A for 5 seasons now. The MD7A seems to have lost some power over the years and is not pushing the boat like it used to. Maintenence consists of changing the oil, oil filter and fuel filters. Is there anything else I should be doing? Any thoughts or suggestions?

When you say you've lost power-I assume you boat is in the water-if so-is it possible you have stuff growing on the prop? this will cause an unexplained power loss-where the motor runs fine but just doesn't seem to push the boat-however-difficulty in starting is a sign of ring/cylnder wear-do not use ether-ever-you can trash your engine completely-they fire on compression and heat-not on spark like a car-if the cylnder pre-ignites before top dead center it will send the piston smashing back down and damage the rods and crank-shaft-I bought a boat with an MD2B motor with a can of ether in the cabin-I didn't know and the surveyor did not mention it-the motor was junk-and this little bit of info cost me $3,200-(12 years ago that was alot of money)-sorry I can't give you better news.



grenier@ma.ultranet.com

[Pete]

Also the engine needs help starting in cold weather (ether or hair dryer). Any suggestions? Last fall when preparing to make the last run from Bailey's Harbor to Sturgeon Bay for haul out I had trouble starting the engine. It was cold so I used the hair dryer. The engine turned over, ran rough for 30 seconds or so and quit. I tried some ether with same result. I repeated this process 5 or 6 times (using ether) with the same result. Then I noticed a thin powdery black soot covering the water near the the exhaust through-out my slip (don't tell the EPA!!). It seemed like maybe the engine wasn't getting fuel consistently so I changed the large fuel filter. Problem solved! However, I averaged maybe 3.5 knots back to Sturgeon Bay. There were rough seas and a head wind. Still this seems pretty slow. Your thoughts? Thanks!!



peter@zwiefelhofer.com

[Tom]

I've owned a 1981 CD30 w/ an MD7A for 5 seasons now. The MD7A seems to have lost some power over the years and is not pushing the boat like it used to. Maintenence consists of changing the oil, oil filter and fuel filters. Is there anything else I should be doing? Any thoughts or suggestions?

When you say you've lost power-I assume you boat is in the water-if so-is it possible you have stuff growing on the prop? this will cause an unexplained power loss-where the motor runs fine but just doesn't seem to push the boat-however-difficulty in starting is a sign of ring/cylnder wear-do not use ether-ever-you can trash your engine completely-they fire on compression and heat-not on spark like a car-if the cylnder pre-ignites before top dead center it will send the piston smashing back down and damage the rods and crank-shaft-I bought a boat with an MD2B motor with a can of ether in the cabin-I didn't know and the surveyor did not mention it-the motor was junk-and this little bit of info cost me $3,200-(12 years ago that was alot of money)-sorry I can't give you better news.

My mechanic told me that if I had a can of ether on the boat to spray it on my hands and then take a rag and wipe the grease off. If any ether was left to throw it away and NEVER put it in the engine.



TomCambria@mindspring.com

[Bill]

Also the engine needs help starting in cold weather (ether or hair dryer). Any suggestions? Last fall when preparing to make the last run from Bailey's Harbor to Sturgeon Bay for haul out I had trouble starting the engine. It was cold so I used the hair dryer. The engine turned over, ran rough for 30 seconds or so and quit. I tried some ether with same result. I repeated this process 5 or 6 times (using ether) with the same result. Then I noticed a thin powdery black soot covering the water near the the exhaust through-out my slip (don't tell the EPA!!). It seemed like maybe the engine wasn't getting fuel consistently so I changed the large fuel filter. Problem solved! However, I averaged maybe 3.5 knots back to Sturgeon Bay. There were rough seas and a head wind. Still this seems pretty slow. Your thoughts? Thanks!!

;The engine sounds like for sure you should do a compression check,ether can really put a strain on the head gasket, in fact the engine manual calls for a retorquing of the head every few hundred hours of operation.Will be interested in the final diagnosis.



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