Oil weeping Volvo MD11c

[Dave]

My engine has a small oil leak. Whenever I run it I get a little weepage and only find the oil on the starboard motor mount. It gets into the water that drips from the packing gland and is driving me nuts. I cannot find the leak and have made sure the breather hose is going into the intake.

Any ideas?

[Dulcinea]

Someone at my yacht club recently asked me why I repowered. I began my response with I had a Volvo...and they stopped me.  "say no more". These engines, especially those with 1500 hours or more will be nothing but expensive headaches until the real problem is addressed.  There is not enough "fixing" and not enough money that will rectify the problem. I love Pearson boats (on my third one now) but I cannot fathom what they were thinking with these engines.  Maybe some purchasing agent got a good deal.

[Dave]

Just an update. I always have a little oil on the starboard motor mount, not enough to drip, but enough to keep it shiny. It is right by the oil filter. I occasionally notice a little oil in the water under my  shaft. This drives me batty that I cannot find the source.

[rkfitz]

It could be a leak in the water pump shaft seal, or it could be a fuel leak around the fine filter.

[Dave]

I am leaning toward front seal. It is irritating but so low that I do not feel the need to pay someone to disassemble to replace the seal.

[Libations Too]

Dave,

I am in the middle of replacing my raw water pump....now waiting for a new pump to arrive. The oil seal at my water pump (a Johnson 10-35157-3) is a simple O-ring that rests in a small groove in the water pump base and presses against the flat surface of the engine block. The O-ring part is cheap at a couple dollars and easy to check or replace. The hardest part for me was removing the short piece of hose connecting the water pump to the "water pipe" that carries the cooling water up to the exhaust manifold.

I believe there must also be an oil seal on the shaft of the pump itself...but getting to that seal would require a pump rebuild. I chose not to go the rebuild route since I didn't have the capability and confidence that I could successfully press seals and bearings off of and on to the pump shaft.

My raw water pump failed at the shaft seal at the water end of the shaft, resulting in an annoying drip, drip, drip of sea water. At first I thought it was a bad gasket at the pump's cover plate but it turned out to be the more serious seal at the shaft.

[Dave]

Thank you for the information Richard

I have done some checking and it seems like if the oil was weeping here it would be a bearing that is on the shaft. I am trying to find more information as I also lack the ability to properly press a new bearing on the shaft. At least now I have a place to refine my search. I did find this page useful in understanding the pump better with good photos.

http://coxengineering.sharepoint.com/Pages/Waterpump.aspx

[Libations Too]

Another view of the MD11C water pump: http://www.marinepartseurope.com/en/volvo-penta-explodedview-7742230-26-15111.aspx

This view is of the entire cooling system. The O-ring that I mentioned earlier fitting between the pump body and engine block is part number 24. http://www.marinepartseurope.com/en/volvo-penta-explodedview-7742230-26-15106.aspx

Note that the part number for the water pump on these pages does not correspond directly to the Johnson 10-35157-3 pump that I had on my MD11C. I ended up confirming that the Johnson 10-35157-3 pump was a suitable replacement part for the Volvo part number 833883 shown in the diagram above by a cross reference on another website: http://www.pumpvendor.com/Johnson_10-35157_series.html

Hope this helps. Good luck!

[Dave]

I have read of people that had a leak at their pump shaft seals and they said they got water in their crankcase also. I have had no water getting into my oil. Any thoughts?

[Libations Too]

Dave,

I think it very possible for water to get back into the crankcase...but that was not the case for me. If you look at the pump diagram, you can see two seals separated by a spacer washer (part numbers 9, 10, and 13). The spacer ring is positioned between the water seal and the oil seal and is aligned with small openings in the pump body. I have no idea of design intent but it seems likely to me that the small openings in the pump body were intended to allow the leaking fluid (either water or oil) to drip/weep from the pump so that it could be easily detected.

When my pump failed I saw the drip, drip, drip from the bottom of the pump cover plate...making me think at first that I had a leaking cover plate gasket. Only after using a small mirror and looking up at the pump housing (behind the pump cover plate) did I see a corrosion trail leading from the small openings in the pump body. My guess is that if the oil seal failed first the same thing would happen but the drip, drip, drip would be oil instead of water. Whether leaking oil would work its way back to the starboard motor mount as you have described is another question.

Perhaps other pumps for other engines only have one seal between the water and oil sides of the pump. In that case it would be more probable that water would enter the crankcase when the seal failed.

[rkfitz]

Hey Dave, Richard is spot on. The o ring he referenced is the only place on the water pump an oil leak could develop. If the shaft seal was leaking you would see water leaking into your crankcase.