1979 Volvo Penta MD-11C -- Water and Oil Leaking from Air Filter

[Michael T.]

Our 1979 Volvo Penta MD-11C diesel engine has been a reliable engine for our Pearson 323. However, just recently, when we were motoring after we refueling, it started to make a banging sound similar to a car's backfiring but not as loud. When it bangs, the boat would shake and smoke would seep out of the aft-most air filter. I noticed that water was also leaking out of the air-filter during the bang also, but after I removed and re-tightened the air-filter, the water leak appeared to stop or mostly stop.

Does anyone have any idea what could be causing this? I've checked the exhaust elbow and while I was able to scrape out some carbon deposits, it was in good shape and clear so that the water and exhaust could flow unobstructed. The fuel filter bowl doesn't appear to have water or foreign particles in it; however, admittedly, a portion of the fuel was several years old because we hadn't consumed much fuel when wailing. Our lightly used engine (about 500 hours) uses raw water for cooling (no enclosed coolant) from the Potomac River/Chesapeake Bay.

Thanks for any suggestions you might have.

Mike T.

 

[michael_w]

Sounds like head gasket failure.

 

[shanemax]

To have water in an air filter is either rain water or some sort of back pressure from the cooling system. Water in an air filter would usually result in the engine stopping and a risk of locking up the engine, hydro lock, trying to compress a none compressible liquid can do immense damage.

 

[Stemar]

Sounds like head gasket failure.

That would be my first guess, too. I think a compression test would my first step.

 

[Michael T.]

Sounds like head gasket failure.

Thank you for your reply. I'll replace the gaskets and see if that corrects the problem.

 

[Michael T.]

That would be my first guess, too. I think a compression test would my first step.

Thank you for your comment/reply. I'll also do that before replacing the gaskets.

 

[Michael T.]

To have water in an air filter is either rain water or some sort of back pressure from the cooling system. Water in an air filter would usually result in the engine stopping and a risk of locking up the engine, hydro lock, trying to compress a none compressible liquid can do immense damage.

I've not run the engine but for a few minutes after it starts to make the knocking sound out of fear of it possibly locking up. Because it always starts normally, sounds good for a minute or two, then begins to make the knocking sound. After a few minutes, I shut it down to prevent damage.