Yanmar 4jh2E oil consumption problem

[mikesdeb]

I recently replaced a corroded oil cooler on our 1994 Yanmar 4Jh2E diesel engine. However we are still consuming large amounts of oil (1 quart per hour, idling the engine at 1500 rpm). There is only a small amount of oil in the sump, and not a lot of blue smoke from the exhaust. I checked the exhaust water and could not detect any oil there either.

Does anyone have any ideas as to where the oil is going?

 

[VicS]

Its not leaking into the bilges?

Are you absolutely sure its not in the exhaust water. Collect a bucket full. There will be a sheen from a bit of unburnt diesel at idle probably but you should spot lube oil if you are losing it at the rate you say via that route.

if you were burning it at that rate the engine would be revving instead of idling properly I would have thought, blue smoke or not, and it might not stop immediately you try to stop it. Also if you are burning it then you would probably get a cloud of blue smoke if you revved it briefly.

The engine is fresh water cooled is it not? Is it going into the freshwater circuit. Take the cap off the header tank and look for oil. Is the oil cooler in the fresh water circuit or the raw water circuit?

I don't understand your statement "There is only a small amount of oil in the sump" it should be at the correct level surely. Top it up before investigating further.

 

[mikesdeb]

Thanks for your post. I haven't spotted any oil in the exhaust water or in the fresh water system. The engine is fresh water cooled, and the oil cooler is in the raw water circuit.

I meant the area under the oil pan, as there is a small leak probably from the rear seals. However this is really a small amount.

Still looking!!

 

[wotayottie]

In the end, there are onmly a limited number of places it can go.
1/ It can be burned in combustion, but I agree with Vic you would likely see this quantity causing the engine to run on
2/ It can leak to underneath the engine ie the sump - but you say thats not the case
3/ It can disappear into the raw cooling water from, for example, the oil cooler.

No 3 is my favourite. I had a similar problem with a raw water cooled 2gm where the oil was going into the cooling water. The only time I could really see it was in ther marina, on a flat calm day with the lock gates shut and no one running their engines. Then it became clear that most was going into the water and a fair bit burning off in blue smoke.