yanmar 4jhe - white smoke and oil sheen on water

[JBsurfin]

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?

I wouldn't be posting any pictures of your vessel producing a oil sheen. For one, if within US waters, you are required to report it. 2) all it takes is one person to report it to the USCG. Massive fines.. Violators
are subject to a penalty of $5,000.

[sailorboy1]

oh come on

[pdecker]

I had the white smoke with oil sheen on the water problem. It took awhile to diagnose, but my problem was due to a broken exhaust valve. I had good compression on cylinders 1 - 3 and zero on 4. Had to remove the head and replace the head gasket, valves and other parts. I did a complete write-up in our blog: https://undertheboom.com/suck-squeeze-bang-blow/

Nigel Calder in "Marine Diesel Engines" lists eight possible causes of white smoke on the troubleshooting table on page 70: air in fuel lines, dirty fuel, piston blow-by, dry cylinder walls, valve blow-by, decompressor levers on/valve clearances wrong / valves sticking, pre-heat device inoperative, and blown head gasket / cracked head / water in cylinders. It wouldn't hurt to try adjusting valve clearances since the only cost might be a new valve cover gasket. Good luck in finding the cause.

[Epikur]

Before doing any repairs I would run the engine at high loads (where it wants to be). For a sailboat engine that means running it at above 2,000 RPM with the gear engaged, either tethered in the berth if cleats are up to the task or, better, running the boat an hour at 5 kts.

Someone said: „don’t baby your diesel“

I have this „problem“ every time I start the season after the boat was out of use for some time. It disappears after some time under reasonable engine load.

[rslifkin]

Thinking about it, the last time someone I know had an issue like this, it turned out to be a plugged fuel filter. The engine was being fuel starved enough to experience some misfires, causing raw diesel to be blown out the exhaust.

[skipperpete]

rslifkin, you’re right about the white smoke and clogged filter. In my instance it was a blocked secondary filter and the white smoke was substantial. The engine was an almost new Yanmar 4JH5 and had never had the secondary filter changed since the engine was installed, a new filter instantly eliminated the problem and to this day I can’t explain why. It makes no sense in the general “smoke related” scheme of things that a blocked filter could cause heavy white smoke but it definitely did on this occasion.

[BAD ORCA]

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?

Does the smoke mostlly go away after the engine gets up to temp?

I have the same problem. Mine is because i have a bad/loose valve stem in the head above my #1 cylinder. When i start the engine I get huge plumes of white smoke and fuel on the water surface. The bad valve prevents the #1 cylinder from combusting the fuel until the engine gets up to about 140deg, then the piston is able to combust the fuel and the smoke mostly goes away but not entirely. Engine then runs perfectly fine after that and will restart after a couple hours sail with little to no smoke on startup. Its only if the engine has sat for a day or so and had time to completely cool off that it begins again.

[skipperpete]

Originally Posted by BAD ORCA

Does the smoke mostlly go away after the engine gets up to temp?



I have the same problem. Mine is because i have a bad/loose valve stem in the head above my #1 cylinder. When i start the engine I get huge plumes of white smoke and fuel on the water surface. The bad valve prevents the #1 cylinder from combusting the fuel until the engine gets up to about 140deg, then the piston is able to combust the fuel and the smoke mostly goes away but not entirely. Engine then runs perfectly fine after that and will restart after a couple hours sail with little to no smoke on startup. Its only if the engine has sat for a day or so and had time to completely cool off that it begins again.

So is that basically a low compression problem because the valve isn’t seating properly?

[BAD ORCA]

Originally Posted by skipperpete

So is that basically a low compression problem because the valve isn’t seating properly?

I should have worded my comment a bit differently i think and said that that's my best guess, not that thats absolutely the cause. Full disclosure, im no diesel mechanic.

I do have a decent amount of blowby when i open the crankcase cover but i have not pulled the head yet to get a better look at the other side. That particular valve on #1 piston wiggles quite a bit (about 1/16" from side-to-side) in the valve guide where as all the others are solid with no movement at all.

My guess is that the blowby is coming from that valve into the crankcase preventing propper compression. Maybe the valve seats just well enough when the engine gets hot to close up enough to allow the piston to ignite the fuel. I'd love to get opinions on this if it might help diagnose the OP's problem but i dont want to hijack his thread. .

[Eder]

You have air leaking into the fuel line.

[bil56]

this lateral wiggling in the valve guide is abnormal:
loss of compression, oil consumption, risk of breakage ...
you will have to take this head apart soon

[skipperpete]

Originally Posted by BAD ORCA

I should have worded my comment a bit differently i think and said that that's my best guess, not that thats absolutely the cause. Full disclosure, im no diesel mechanic.

I do have a decent amount of blowby when i open the crankcase cover but i have not pulled the head yet to get a better look at the other side. That particular valve on #1 piston wiggles quite a bit (about 1/16" from side-to-side) in the valve guide where as all the others are solid with no movement at all.

My guess is that the blowby is coming from that valve into the crankcase preventing propper compression. Maybe the valve seats just well enough when the engine gets hot to close up enough to allow the piston to ignite the fuel. I'd love to get opinions on this if it might help diagnose the OP's problem but i dont want to hijack his thread. .

Not really a hijack if you have the same smoke problem and the same engine, you might have information that will answer the OP’s question …
what engine is it that has a wobbly valve stem?

[BAD ORCA]

Originally Posted by bil56

this lateral wiggling in the valve guide is abnormal:
loss of compression, oil consumption, risk of breakage ...
you will have to take this head apart soon

Much thanks, noted. Luckily i have been busy with other projects on board and have not used the boat (motoring) in well over a year.

[BAD ORCA]

Originally Posted by skipperpete

Not really a hijack if you have the same smoke problem and the same engine, you might have information that will answer the OP’s question …
what engine is it that has a wobbly valve stem?

Different engine, 1980 Universal 5432. I noticed it while adjusting valve clearances. If his smoke dissipates after running for a while, which it looks like in his second pic, he may have a valve problem.

Once my engine heats up, it runs perfectly normal once #1 piston starts to combust, power, temps and oil pressure are also normal on my engine as well, same as OP.