Yanmar 3GM30 blobs or oil and white smoke

[mikedefieslife]

Not started my Yanmar 3GM30 in a while (maybe a month or so) and last time I did I probably didn't rev it particularly high.

Started it today and it was running nicely until I got well over 2,000 rpm then I started to get a little white smoke, and a few oily deposits from the exhaust.

Pushed on to much higher RPMs and there was a ton of white smoke and large blobs of oily residue pouring out of the exhaust. Not good for the environment nor my wallet I imagine.



Back down to lower RPMs and just had normal running again.

I was thinking that maybe I should check the exhaust elbow, but this is a raw water cooled Yanamr so the raw water doesn't enter via a barb on the elbow but instead on the exhaust manifold. I understand on elbows with the barb that the welding is prone failing between the barb and the inner tube.

Any suggestions on areas to inspect?

[Lepke]

White smoke is usually unburnt diesel or steam. It could be from the engine running at too cold of a temperature. Raw water engines have a lower temp thermostat to prevent buildups. If you're in especially cold water, the engine may not be fully warmed up. Diesels run better at higher temps. Or it could be low compression in one or more cylinders. You could have a bad injector allowing too much fuel.
Steam comes from water entering the cylinder from a cracked head/block or bad head gasket.
Do a compression or leak down test.

[a64pilot]

Google Diesel stacking or slobbering and see if you think this could be your issue, sounds like it could be to me.
It’s not real complex but more to it than I would like to try to cover in a post.
Cure is to run her hard to burn off the accumulated unburned fuel and oil

[mikedefieslife]

Yep it is wet stacking/slobbering.

I ran it again, got it nice and warm, and found the problem starts at around 2250rpm. I guess it is there before that but you have to look for it.

Smoke at 2,500 rpm


Exhaust elbow


The part the exhaust elbow mates too. There water hole was mostly blocked by carbon deposits.

[mikedefieslife]

I cleaned up the elbow and manifold. There is plenty of water from the exhaust so I do not believe that the elbow is the issue.

Ran it again up and runs beautifully until 2250-2500 rmp. It will not then want to rev higher. The smoke turns from greyish-white to dark grey/black and the semi combusted diesel starts pouring out.

What are next steps? Try to get the probably seized injectors out and send them off for cleaning?

[Sailmonkey]

Is this happening while in gear tied to the dock or while running free or out of gear and just ramping up the idle?

If in gear is the prop clean? Or are you over propped?

[mikedefieslife]

Some of the guys on Facebook think it's because I'm doing a bollard pull. Tied to the dock. It had crossed my mind, but then I watch other cruisers here do the same without the mess. Slightly newer Yanmars though.

Prop is clean as it's a drive leg that lifts out of the water.

[Sailmonkey]

If your slightly over propped to just perfectly propped, the engine would overload while pulling against the dock. The overload will load the water with block blobules like your seeing.

Run it wide open while underway and report back

[peteatbeach]

I'd like to pick up and continue this thread if that is okay.

We had our boat laid up in Grenada for the summer/fall. Didn't have any problems with either engine (catamaran) prior to lay up, but had the sail drives pulled, cleaned and seals replaced. After we splashed no problems. But shortly after getting into open water I noticed that the stbd engine would not get above 2200 RPM, and was putting out a lot of black smoke when I pushed the throttle up to what should have been 2700 RPM. If I kept the engine at 2000 RPM no problem. If I went slightly above I get blue/grey smoke. Mechanics I conferred with thought it was an issue with injectors. I replaced all three with new injectors (noted what looked like oil on the compression washers), but still had grey/blue smoke. Later, I removed the exhaust elbow and found it was fouled. Cleaned elbow and manifold, and replaced gaskets. Now we get normal range of RPMs, but still putting out a grey smoke above 2000 RPM. The engine starts immediately on cranking, so I don't believe I have a compression problem - meaning I don't think I have a problem with rings.; and no blow back pressure when I hold my hand over the oil fill port on the valve cover.

What I'm trying to figure out is where oil could be coming from that would get into the cylinders. Checked valve guides and seats - no apparent issues. No apparent external oil leaking from head or other gaskets. I'm concerned that when we were trying get the engine above 2000-2200 RPM with the exhaust elbow blocked, did we cause an over-pressure condition and blow an internal seal or something similar.

Suggestions?

What was the resolution to the issue on the original post?

[mikedefieslife]

In my case it was just being over propped and doing a bollard pull. Been cruising all season and so far it's been running well. Of course it won't now that I've said that

I believe I have a 16/14 prop, judging by what I've heard from the former owner. This doesn't allow the engine to reach max revs which on the 3GM30 is somewhere around 3,400 I think.

[a64pilot]

Originally Posted by peteatbeach

I'd like to pick up and continue this thread if that is okay.

We had our boat laid up in Grenada for the summer/fall. Didn't have any problems with either engine (catamaran) prior to lay up, but had the sail drives pulled, cleaned and seals replaced. After we splashed no problems. But shortly after getting into open water I noticed that the stbd engine would not get above 2200 RPM, and was putting out a lot of black smoke when I pushed the throttle up to what should have been 2700 RPM. If I kept the engine at 2000 RPM no problem. If I went slightly above I get blue/grey smoke. Mechanics I conferred with thought it was an issue with injectors. I replaced all three with new injectors (noted what looked like oil on the compression washers), but still had grey/blue smoke. Later, I removed the exhaust elbow and found it was fouled. Cleaned elbow and manifold, and replaced gaskets. Now we get normal range of RPMs, but still putting out a grey smoke above 2000 RPM. The engine starts immediately on cranking, so I don't believe I have a compression problem - meaning I don't think I have a problem with rings.; and no blow back pressure when I hold my hand over the oil fill port on the valve cover.

What I'm trying to figure out is where oil could be coming from that would get into the cylinders. Checked valve guides and seats - no apparent issues. No apparent external oil leaking from head or other gaskets. I'm concerned that when we were trying get the engine above 2000-2200 RPM with the exhaust elbow blocked, did we cause an over-pressure condition and blow an internal seal or something similar.

Suggestions?

What was the resolution to the issue on the original post?

How long have you run it hard?
It may take up to five minutes for it to clean out all the oil from the manifold etc.