Yanmar, oil in exhaust…

[Pillard]

2002 L42
Yanmar’s 3JH3E

We fired up the engines to weigh anchor. Both were spitting water fine. The wife is at the helm while I hustle the hardware. Within less than a minute of maneuvering for the anchor, she yells at me that something is wrong. A quick glance at the back shows the port engine exhaust is jettisoning oil into the harbor. We shut down the engine immediately, and managed to navigate to our nearby anchorage on the starboard engine.

Once there, I checked the oil and coolant on the port engine. All looks well, as I expected.

I’m not terribly experienced with marine engines, but I was a damn good diesel mechanic on land. I suspect this engine has a heat exchanger between oil and seawater…? Presumably, it has failed?

Or, could this be valve guide seal failure?

Any of your experience would be greatly appreciated before I tear into this.

Thanks.

[FPNC]

If you have a hydraulic gear then you will have a cooler using seawater to cool the hydraulic transmission fluid. So check transmission fluid. Unfortunately, I would think most 3JH3E engines would use a mechanical gear.

This engine does have an oil cooler between the filter and the block. That cooler uses coolant. Not seawater.

You may have valve issues or if you are seeing an oil sheen, it may be diesel from a bad injector.

[Pillard]

Thanks, FPNC. I have a straight shaft, mechanical gear. Oil in it is pristine. I’m starting to suspect a compression test is in order.

[Rumrace]

How many how’s are on the motor.

[Pillard]

Originally Posted by Rumrace

How many how’s are on the motor.

About 2700 hours.

[Cheechako]

Could be an exchanger leak, also could be a stuck injector streaming oil into the cylinder that gets pumped right out into the exhaust. Also if a push rod comes off/valve stuck it will stream unfired diesel right out also.
Can you tell if it's diesel or engine oil?

[Pillard]

It’s black, looks like oil, but carbed diesel can look the same way. What exchanger? I’ve been searching my parts manual, and I can’t find an oil/seawater heat exchanger in the whole system.

I wish I had my compression tester. I may just pull my valve cover and check my push rods. I’m hesitant to tear into here in the middle of the bahamas.

[GreenWave]

If Oil it will stick around on the water for a bit, but if diesel it will dissipate pretty quickly. Any smoke with this incident?

[Cheechako]

Originally Posted by Pillard

It’s black, looks like oil, but carbed diesel can look the same way. What exchanger? I’ve been searching my parts manual, and I can’t find an oil/seawater heat exchanger in the whole system.

I wish I had my compression tester. I may just pull my valve cover and check my push rods. I’m hesitant to tear into here in the middle of the bahamas.

OK... so is it fanning out on the water creating a rainbow sheen? Or is it just carbon blobs on the surface? Some Yanmars do carbon up in the exhaust, especially in the water mixing elbow at the engine exit. It may be just that. I wouldn't start tearing into it either. PS: if the engine is gunned hard sometimes it will break loose some carbon deposits.

FYI: A diesel compression test requires a screw together fitting... you can't just hand hold the gauge in the hole like you can a gas engine...

Not all engines have a transmission or engine oil cooler.

[Compass790]

Stick your hand in the exhaust plume if you are puzzled as to wether it's engine oil or diesel. I dont recommend tasting it but feel & smell should work

[Rumrace]

I’m really good with gas engines but learning Diesels. I have the same motor and my best guess is your common rail and injector timing is messed up. There is a pre burn before the compression stroke. I think that little pre burn injection is hitting closed valves

[Rumrace]

Oh and pardon me rambling but clean up around your exhaust as the raw fuel eats exhaust outlets. Dawn dish soap

[ScottRhodes13]

Originally Posted by FPNC

This engine does have an oil cooler between the filter and the block. That cooler uses coolant. Not seawater.

I don't think this is correct. The manual shows that the oil is raw water cooled.

[Ballsnall]

Originally Posted by ScottRhodes13

I don't think this is correct. The manual shows that the oil is raw water cooled.

Possibly gearbox as well.

[PLeffe]

Perkins has an engine oil cooler on the side of the block. When this fails you pump your engine oil out. It is more than likely this is your problem and a quite dangerous problem in that it is easy to loose all your engine oil quickly.
Look low on the block on the side with the cooler. Follow the hoses and you’ll find it. Inside there is a sleeve that separates oil and water.
Look at a Perkins book. Good luck.