yanmar 4jhe - white smoke and oil sheen on water

[frubens]

Hi,
Our yanmar 4jhe started belching out white smoke and leaking a diesel (or lube oil) sheen on the water mixed in with wet exhaust.
The engine starts up normal and sounds normal when running. Until now no apparent power loss. Exhaust temperature normal, oil pressure normal.
Seemingly no lube oil loss or coolant loss, although I didn't run the engine for long (a few hours max since problem appeared).

Where to start with the diagnosis?

[GreenWave]

Did you do a recent oil change? What does the breather tube look like? Any signs of oil on or around that near the air intake?

[frubens]

Hi, I did an oil change before winterizing in January. Boat has had light use this season.
I did notice some oil on the breather tub where it attaches to the air intake filter and also on the other end.

[frubens]

Hi,
Thank you for the reply!
I did an oil change before winterizing the boat in January this year. The engine has had light use this season. Maybe 10-15 hours or so.
I did notice some oil at both ends of the breather tube!

[GreenWave]

check your oil level. It may be overfilled and some of that oil is coming out the breather tube into the intake. Might just need to drain or suck a little out and then gently clean up that breather tube and the intake.

[Fishspearit]

That's normally a sign of unburnt fuel/excess fuel. There can be a few different causes. Could be low compression (worst case), clogged air filters, or faulty fuel injection. I'd start with the advice above, check oil level, clean air intake and breather to eliminate the possibility of it being lube oil, although that's usually blue not white smoke. Then use an IR camera/gun to see if all the cylinders are heating up the same.

[TeddyDiver]

As Fishpearit says! Reminder for diesel engines, white smoke=>unburned fuel or steam, blue smoke=> engine oil, black smoke=> partially burned fuel when engine is overloaded.

[Tin Tin]

How many hours on it/age, injector timing should be done every 1000hrs / 4 yrs.

[Scubaseas]

Possible injector issue. looks like that when you have a drippy injector. Try cleaning the injectors by using a diesel purge. Fond of LiquiMoly Diesel Purge Injector Cleaner. Follow instructions. Or pull the injectors and send them out for rebuilding.

[Grattaway]

white smoke = water in the fuel.
Check that fuel lines/filters are ok and no water contamination

[frubens]

Engine is from 1988 and has over 2000 hours on it. I chased an air leak for a long time which kept stalling the engine and I'm wondering if it might have contributed to this issue. It is probably time to check injector timing.

Great advise on this thread. will go down the list!

[Scubaseas]

Originally Posted by frubens

Engine is from 1988 and has over 2000 hours on it. I chased an air leak for a long time which kept stalling the engine and I'm wondering if it might have contributed to this issue. It is probably time to check injector timing.

Great advise on this thread. will go down the list!

Unlikely injection timing given it's gear driven and you symptoms seem to have come on quickly. Faulty/dirty injector would be my guess especially in light of a previous stalling issue. The old method of diesel purge was to isolate the inlet and return lines and run the motor, after it was warmed up for 20 minutes at varying speeds but that was back in the 70's and the liquid would dissolve paint and definitely not for sale in California. Now you can buy a new secondary filter and fill it with purge. I fill my filters with purge when I change them in normal service.

One way is to pull all the injectors and send them out for check/repair. Another way is either buy a set and replace (lots of$$) or just buy one cheap Chineseium one or get a used/rebuilt one (ask your friendly Bosch Certified injection shop if they have one) to pull and service the injectors one at a time and then you have a spare.

[Scubaseas]

I could easily be wrong but if you're looking for a starting point, I'd pull up the injectors. If you crank it over with the injectors out remember to remove the nozzle protector and nozzle seat that go between the injector and the head (look at cylinder head diagram).

Adjusting the pump timing can't hurt but i doubt that's the issue.

[bil56]

has the exhaust elbow been removed and checked?
poorly cooled exhaust gas may give white smoke at the exit ...

if the smoke is rather pale grey, check the injectors

[sailorboy1]

Originally Posted by frubens

Hi,
Our yanmar 4jhe started belching out white smoke and leaking a diesel (or lube oil) sheen on the water mixed in with wet exhaust.
The engine starts up normal and sounds normal when running. Until now no apparent power loss. Exhaust temperature normal, oil pressure normal.
Seemingly no lube oil loss or coolant loss, although I didn't run the engine for long (a few hours max since problem appeared).

Where to start with the diagnosis?

When was the last time the engine was run hard and held there for a while?