Water in lube oil-Yanmar

[waterrat365]

I just rebuilt the head on my 21 year old Yanmar YSM 8, the old style horizontal type block. The headgasket blew out last summer and it wasn't run in 6 or 8 months. The old lube oil remained in the block over the winter, along with water in the oil, alas, a kind of grey paste. I rebuilt the head, drained and changed the oil, installed the new head, valves, etc, with a new gasket and sealant, torqued it up, got the engine running with a hair dryer to boost the head temp, and it starts and runs okay now. However, there is still water in the lube oil after 2 oil changes (short running itme-maybe 30 minutes). Is this something which is residual from when the head blew out to begin with? I suspect so, but... The engine had been drained of cooling water during the winter, so it probably wasn't a freeze cracked block. Any ideas? Thanks in advance, Cliff Moore, SV Pelorus, USA

 

[RayJones]

Did you replace the oil filter ? If not, thats probably where the water is sitting.
If you did then it would be nice to know how much water is in the oil and how long after changing it does it turn grey?.
Is the engine fresh water cooled or raw water cooled?
Has the bilge had water in it? I have just had a boat with water in the oil and after extensive investigation and much wasted time the owner told me the bilge had been flooded for two months, further investigation found water had entered through the front pulley seal ( designed to keep oil in not water out ) !
Hope this has helped
Good Luck
Ray Jones.

 

[Guest]

Did you check the head to see if it was flat before you put it back on?. Sometimes it is necessesary to have heads skimmed otherwise the head gasket will blow (again). Is there back pressure in the crank case?

John Dillon

 

[waterrat365]

I should have added: the 1st time I changed the oil, the engine had been running for only 2 or 3 miunutes. There was lots of water in it (grey color), but the oil had not turned very dark from carbon. The 2nd time I changed the oil was after 30 minutes running time, and there was somewhat less water in it, and carbon (black color, with grey from the water) from loading up the engine. I'm assuming for now that since the compression is noticeably greater, and that since there was a clean mating surface, w/o warping or erosion when I replaced the gasket (with a sealant), that none of the water is from blowby around the new gasket, but rather, residual water remaining inside the engine from last winter, reabsorbed into the new oil. I hope...

 

[Guest]

A couple of seasons ago I had a lower unit seal fail on a volvo outdrive and had the milky oil, etc and had it all repaired and all was fine. The following season I had a gear selector seal fail and milky oil again which I replaced ... a few weeks later I had milky oil again but wondered the same as you - had I flushed it all out? So I [on an engineers advice] bought some cheap engine oil [what is used in the drive] and filled the drive up, turned the prop by hand, left it for a day, drained and repeated and that was over a year ago and the oil is fine now ... so my point is that it only takes a small amount of milky oil trapped in the system to colour the new oil! Have you tried flushing oil? I think some of them are designed to absorb water, etc