Diesel Drinking Oil ?

[Tday01]

One of the diesel's on our lagoon 470 (Yanmar 4JH3E - YUE), has started drinking oil. 0.5 L plus every 10 ours. However it is intermittent:

There is no oil leak (bilge bone dry)
No sign of black smoke either under load or in neutral at 1800rpm
No oil in exhaust either under load or in neutral at 1800rpm (after 10 min warm-up).

It seems to use more if it has been run without load at 1800 rpm to charge the engines, but not fully confirmed yet.

Any ideas?

Thanks

Tony
S/V On Delay Lagoon 470 #44
On Delay | A bit of an adventure

[Cil]

Have you checked your ccv (constant crankcase vent) valve or your air filter. If either of these are not up to par oil consumption can be affected. This is often mistaken for a piston ring problem. Courtesy of Captain Mick Sparrow

[Tday01]

Thanks Mick,

I'll check that out. Is there an easy way to check if the CCV is working?

Tony

[Cil]

Take it out, clean it in petrol, rinse, then give it a suck and blow, it should only work one way ie venting positive pressure from the crankcase

[Tday01]

Dumb question.

Where is the CCV valve? I couldn't find it in the manual.


Tony

[Cil]

Hi Tony. On second thoughts, you are probably better off leaving the ccv for a pro. They are infinitely reliable anyway and simply concentrate on ensuring the air filter isn't restricted in any way. If it is restricted, the vacuum from the intake will suck a small amount of oil from inside the engine. If your air filter is good then I would seek proffessional advice. You would definitely notice an oil leak of that volume so it is most likely an internal problem. BTW, does the engine have high hours on it? Regards, Mick.

[Tday01]

Hi Mick,

Engine has ~3000hrs. I think I have established that running at 1800rpm no load, drinks 1/2L in 10 hours. running only under load no oil consumption.

No idea where it goes.

Tony

[Cil]

Hi Tony.
Given that amount of hours you are probably going to have to accept some oil consumption. But make sure your air filter is in good condition anyway.
Good luck
Mick

[bruce smith]

I am no mechanic, but how many of those 3000 hours have been battery charging and how many have been over 1800? Folks say battery charging is a bad use for a diesel. In the same train of thought, have you been battery charging with your other diesel?The one that is not burning oil?

[Tday01]

No idea, we haven't had the boat that long. We alternate between engines for charging. Port engine doesn't consume oil, but it had major work done before we bought the boat.

Tony

[Cil]

Sounds like your starboard engine needs a similar overhaul mate.

Mick

[Target9000]

Originally Posted by Tday01

No sign of black smoke either under load or in neutral at 1800rpm

Just a side note, usually if you're burning oil the smoke is going to be a blue or whitish blue color. Not the black of an overloaded engine.

That oil has to be going somewhere if you're losing that much of it!

Hope you get it worked out Tony! Let us know what you find out.

[bruce smith]

oh , that oil is burning.
Is it getting past the rings?
my guess , yes.

[BriaF]

had new engines installed one used oil.
spoke with engine builders. they suggested running at full
throttle for 10-30 mins
I tried this & it solved my problem
( underway)
diesels like to work hard, running under no load
( charging batteries)
can cause the bores to become glazed.
running at full throttle can remove this gaze
& reseat the rings
Buy a small generator ( honda) & use it to
charge your batteries, it is far cheaper in the
long run

[Tday01]

The odd thing is I don't see the oil burning and most of the time their is no consumption. Then it consumes lots at some point (presumably while sailing as I don't see the smoke).