# slight oil slick in diesel engine exhaust



## mcagney (Jan 9, 2004)

I have a Volvo Penta MD17D (3 cylinder 36HP raw water cooled diesel) that is running perfectly except it is consuming approx one quart of engine oil per 20 hours of operation. The oil in the crank case is clean (not the usual black I would expect from a diesel – no sign of any water intrusion) and the engine always starts first time (without any glowplugs) so I know compression is good. This would suggest (at least to me) that since there is no water leak into the crankcase or soot being deposited (engine oil is not turning black) I don’t have piston ring wear or head gasket leak. However I do observe a very slight oil slick in the cooling water discharge in the exhaust. My question is where is the likely oil consumption leak? Could it be something as simple as a leaking seal in the water pump shaft allowing crankcase oil to enter the cooling system (but not the other way round). Any suggestions as to what I should look for. The engine is 20 years old (don’t know the engine hours).


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## p32 (Sep 22, 2004)

This from a google search cuz I was curious, I can claim very little knowledge on my own:

Symtom:Unburned engine oil in exhaust: 
1)Leak in oil cooler. 
2)Bad shaft seal on raw water pump. 
3)Could be fuel, not oil ? 

This from the site: http://www.geocities.com/bill_dietrich/BoatEngineMaintenance.html.


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## Dumah (Feb 18, 2010)

That oil consumption is way too high, suggest you have a leak in the lube oil cooler or raw water pump. Either way,I would be investigating and curing before the engine itself starts inhaling water. Not familiar with that particular engine, but usually there is an oil passage to the head that relies on the head gasket for sealing, if the engine is "dry" at rest (water drains back after running) it could possibly be the head gasket.

Hope this helps,
Cheers, Dumah
Halifax, NS


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## klem (Oct 16, 2009)

Yes, that oil consumption is very high. I do not believe that an MD17 has an oil cooler but I may be mistaken. I would check your waterpump to start with. Is there anything coming out of the weep hole? Are you sure that there is no water in your oil? There is usually contamination both ways which will slowly turn your oil milky white.


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## sailingdog (Mar 19, 2006)

Guys—

If he still has an oil problem, he's created a slick the size of the one the Valdez left behind, since he was posting in 2004.


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## klem (Oct 16, 2009)

Whoops. Thanks for catching that SD. I only looked at the time of the post above mine, not the OP.


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## desert rat (Feb 14, 2013)

check the compression, check if the rocker arm bushings are worn wobble excessively. Low compression or worn rockers replace engine. Sorry.


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## MarkSF (Feb 21, 2011)

Can't believe you just answered a 3-year old answer to a 9-year old post.


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