yanmar jh4te burns oil

[Eddie]

I have had the boat 5 years and put 700 hours on the engine. It runs fine except for burning 3/4 quart every 8 hours. Only notiecable smoke on startup. IWhen i bought the boat ,the engine had 10 hours on it,the boat had mostly been layed up. I don't know how often it was started before i obtained her. I am guessing a stuck ring. Any recommendations on cause of the burn and repair,or better to just live with the consumption? Thanks

[model 10]

It's better than if it was leaking that much oil into the bilge. A bad turbo seal can use up that much oil.

[ontherocks83]

That seems like a significant amount to me. I would start with a compression check or better yet a leak down test and go from there. That would probably be your most expensive repair if the test goes poorly so may as well look into that first before you spend money else where. The leak down test I feel is a bit more accurate and conclusive compared to a normal compression check if you can get one done.

[ColdEH]

Originally Posted by Guy

It's better than if it was leaking that much oil into the bilge. A bad turbo seal can use up that much oil.

I was going to suggest the same thing, look at the water coming out of the exhaust or collect it in a container after the engine is warm , see if there is oil floating in it .

Regards

[MARINE ENGINNER]

Originally Posted by Eddie

I have had the boat 5 years and put 700 hours on the engine. It runs fine except for burning 3/4 quart every 8 hours. Only notiecable smoke on startup. IWhen i bought the boat ,the engine had 10 hours on it,the boat had mostly been layed up. I don't know how often it was started before i obtained her. I am guessing a stuck ring. Any recommendations on cause of the burn and repair,or better to just live with the consumption? Thanks

How many hours does this engine have?

M.E

[a64pilot]

I'd put sea foam in the oil and run it hard for at least an hour. I define hard as a couple of hundred RPM under max no less.

[a64pilot]

Oh and a turbo seal often shows up as oil in the intake if you take the turbo loose. It certainly could be a turbo seal assuming it's not a NA engine

[donradcliffe]

If you are really burning a quart every 12 hours, you would see billowing smoke. Its much more likely an oil leak.

[a64pilot]

Originally Posted by donradcliffe

If you are really burning a quart every 12 hours, you would see billowing smoke. Its much more likely an oil leak.

Average oil consumption for a little airplane engine is one qt every 10 hours and they don't smoke

[model 10]

Originally Posted by donradcliffe

If you are really burning a quart every 12 hours, you would see billowing smoke. Its much more likely an oil leak.

Oil out the turbine does not always smoke. Hardly ever actually in a water lift system. Oil out the compressor might if it were very very bad but of course you would see the mess in the intake.

[sailorchic34]

From personal experience, 3/4 quart in 8 hours does not cause smoke.

So does the engine start easy and or does one cylinder seem to take longer to fire. That is does the engine rpm increase after 15 ish seconds without touching the throttle?.

[ontherocks83]

Sailorchic your kind of a guru at engines now. Maybe you can convince him to pay you to travel to him to fix his engine and then post the repair on here for all of us to see. Your last repair had quite a following. I think we would all enjoy a sequel!!!!

[jcapo]

Originally Posted by sailorchic34

From personal experience, 3/4 quart in 8 hours does not cause smoke.

Hmm, I have a 4jh-dte not a 4jh4. Last November I began to burn a few ounces of oil every 10 or so hours with very noticeable blue smoke. Worse at startup. Maybe valve stem seals.

Originally Posted by sailorchic34

So does the engine start easy and or does one cylinder seem to take longer to fire. That is does the engine rpm increase after 15 ish seconds without touching the throttle?.

Mine starts in less than a second and runs fine. Fuel consumption might be up a bit. Hard for me to tell.

I'm leaning toward replacing the valve stem seals first.

[J Clark H356]

Do you have a feathering prop? If so, it could be a prop over pitch causing your problem. I have 1080 hours on my MaxProp and it needs to be reconditioned. I was running at cruise like I always had, but it was 90% of full rpm rather than 75%. I was burning more fuel and didn't understand why. I had not run my engine up to max rpm for quite some time. When I finally did, I was only getting 3100 where it had been 3,450. My max rpm had lowered due to gradual MaxProp internal wear which over pitched the prop. I was burning oil and excess fuel and generating a lot of soot on my stern. This is just another thing to consider.

[jcapo]

Very close to max rpm measured with a hand held laser tach. I sold my Max-prop and installed a fixed prop last year.

Didn't mean to hi-jack this thread.