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Old 10-01-2018, 04:04   #1
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Yanmar 3GM30 blobs or oil and white smoke

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?
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Old 10-01-2018, 10:15   #2
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Re: Yanmar 3GM30 blobs or oil and white smoke

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.
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Old 10-01-2018, 15:06   #3
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Yanmar 3GM30 blobs or oil and white smoke

Google Diesel stacking or slobbering and see if you think this could be your issue, sounds like it could be to me.
Itís 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
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Old 11-01-2018, 07:09   #4
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Re: Yanmar 3GM30 blobs or oil and white smoke

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.
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Old 12-01-2018, 04:50   #5
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Re: Yanmar 3GM30 blobs or oil and white smoke

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?
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Old 12-01-2018, 05:47   #6
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Re: Yanmar 3GM30 blobs or oil and white smoke

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?
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Old 12-01-2018, 05:56   #7
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Re: Yanmar 3GM30 blobs or oil and white smoke

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.
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Old 12-01-2018, 16:41   #8
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Re: Yanmar 3GM30 blobs or oil and white smoke

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
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