Yanmar 4JH110 black smoke and limit at 2100rpm

[XtaSea]

Identical Yanmars on a catamaran. Starboard runs well. Hits 3,000rpm easily. No smoke.

Port limits at 2,000-2,100rpm. Black smoke. Especially dense smoke in reverse.

User’s manual says the engine is rated at 3,200rpm. Is that the max rpm for short periods of time? What is the recommended operational rpm range? I hear turbos like to be run high regularly to prevent hydrocarbon build-up.

This boat has been unused for long periods of time. I suspect the turbos have not been exercised. ~1,100 hours on each.

Thanks for the help.

[Wotname]

I would be looking at the exhaust system first (mixing elbow etc for blockages) and then the turbo. I won't delay.

[Wotname]

Originally Posted by XtaSea

.........

User’s manual says the engine is rated at 3,200rpm. Is that the max rpm for short periods of time? ...........

AFAIK, that is the continuous max rpm; pretty sure intermittent (2 hour) max is rpm is 3,400 or 3,600 however I don't have the manual nearby to check.

[rocks]

I had the same problem, found the starboard turbo was stuck. The motor had not been started for over 1 year (due to Covid-19). At ~ 2200 rpm the motor started to make smoke.

The Mechanic put a socket on the air intake side of the turbo and freed the turbo up. We then took the boat out, ran the motor with the turbo at full boost for about an hour. The Mechanic said it’s a common problem with boat sitting a long time. Have not had a problem since.

[XtaSea]

Would/should the oil level go down if this port engine is run >2,000rpm with black smoke?

[XtaSea]

rocks, did he remove any parts to gain access to that nut?

[rocks]

Removed the air filter.

[Compass790]

Originally Posted by XtaSea

Would/should the oil level go down if this port engine is run >2,000rpm with black smoke?

No the oil level should not go down. The black smoke is from too much fuel for the amount of oxygen in the cylinder probably cused by stuck turbo as stated earlier.
Back off the throttle until it doesnt blow black smoke until you free/fix turbo.It aint good for anything overfuelling.

[skipperpete]

Originally Posted by XtaSea

Identical Yanmars on a catamaran. Starboard runs well. Hits 3,000rpm easily. No smoke.



Port limits at 2,000-2,100rpm. Black smoke. Especially dense smoke in reverse.



User’s manual says the engine is rated at 3,200rpm. Is that the max rpm for short periods of time? What is the recommended operational rpm range? I hear turbos like to be run high regularly to prevent hydrocarbon build-up.



This boat has been unused for long periods of time. I suspect the turbos have not been exercised. ~1,100 hours on each.



Thanks for the help.

I support Wotnames suggestions and would offer a quick diagnosis tool to assist.......... take off the air strainer/filter on the intake side of the turbocharger while the engine is stopped and cool and try to rotate the compressor wheel with the tip of your finger, no tools allowed, it’s very fragile. If it is stuck , usually it means that the turbine is impeded or locked by corrosion between the turbine wheel tips and the exhaust scroll housing ( the gap is very small even on a new turbo). The corrosion is caused by the humidity in the wet exhaust and is a very common problem and you need to remove the turbo to either replace the water cooled turbine scroll or polish off the corrosion with abrasive paper or a little flap disc in a power tool. The turbo scroll is easy to separate from the cartridge and once you get the mixer elbow off you should be able to see where the turbine tips are touching.
The air strainer is a bit of a wriggle to get it oil from under the intercooler pipes but it can be done.
Did you get any error codes? Here’s page 1 of the failsafe shutdown levels, there is a possibility of a rogue injector and the readout will identify it.
While you have the mixer elbow off, take a close look inside. They have a fairly short lifespan.......

[bstreep]

We own a 4JH with a turbo. My bet, EVERY time: Turbo. It needs to be serviced. The symptoms you have point perfectly to it. It's a job I hate, but I can get it off in about 45 minutes now, and back on in just over that.

[jewt]

I knew there was a number of very good reason never to own a turbo engine

jewt
S/V Bifrost-8
New Bern, NC

[skipperpete]

I don’t blame the turbo.......the wet exhaust is the real culprit.

[bstreep]

No. It's the turbo. They don't belong on a sailboat. We abuse them - we start them up to get out of the slip, and then run them just long enough to get the sails up. Then repeat the reverse. We never seem to run them hard (we sailors are tight about our fuel consumption), to keep the turbo clean.