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View Full Version : Yanmar 6LP-STZE Lube oil oin Coolant...ideas? Its not the internal Lube oil cooler...



Mark Powers
08-15-2011, 09:19 PM
Hello fellow boat owners and all around marine oriented folks.

I have (several) yanmar 6LP STZE 315HP diesel engines in 32' charter boats here in Alaska. We have one that is bleeding engine lube oil into the coolant (fresh water side...boat has raw salt water to fresh water heat exchanger). We have torn into the internal lube oil cooler located unter oil filter and pressure tested that assembly AND inspected the head gasket. Neither appear to be failed. We are getting A LOT oil engione oil into the coolant...need other ideas...??? Failed block? Has anyone seen this before? Two Yanmar dealers that we use are scratching thier heads.

Walter Brun
10-20-2011, 05:44 AM
Hi Mark,

I once had a similar problem On a Volvo 41,oil in the freshwater system and it came from a small hole in the lower part of the cylinderliner(wet) just above the seals.
It was a casting impurity and I scrached my head too,had to take the engine apart to find it.
Have you solved the problem yet,let me know.
good luck Walter


Hello fellow boat owners and all around marine oriented folks.

I have (several) yanmar 6LP STZE 315HP diesel engines in 32' charter boats here in Alaska. We have one that is bleeding engine lube oil into the coolant (fresh water side...boat has raw salt water to fresh water heat exchanger). We have torn into the internal lube oil cooler located unter oil filter and pressure tested that assembly AND inspected the head gasket. Neither appear to be failed. We are getting A LOT oil engione oil into the coolant...need other ideas...??? Failed block? Has anyone seen this before? Two Yanmar dealers that we use are scratching thier heads.

ccarson
12-09-2011, 07:16 PM
did you resolve the water in oil problem? i have a 6ly2A with the same issue. any thoughts?