Black smoke on yanmar diesel

[seaman-lew]

check fuel injection

[Compass790]

Disagree with saying it's oil smoke, black smoke is normally from unburned fuel. You have some kind of overfuelling or overloading issue or compression problem. I would test compression, clean bottom, clean injectors ( check youtube) You decide the order. Oil smoke is normally blueish at least if engine warm

[skatun]

Originally Posted by MIRELOS

Check the oil dip-stick, did you put a tad too much oil, black smoke and engine racing not idling could be too much oil

Oil changed, 3/4 full, its pretty black though..

[skatun]

Originally Posted by Compass790

Disagree with saying it's oil smoke, black smoke is normally from unburned fuel. You have some kind of overfuelling or overloading issue or compression problem. I would test compression, clean bottom, clean injectors ( check youtube) You decide the order. Oil smoke is normally blueish at least if engine warm

I did clean and test opening pressure of injectors, hopefully this weekend I will do the compression test.

[skatun]

Originally Posted by Jman

Here is another quick thing to look for that had me stumped for longer than it should have.

Yammers, at least the 3gm have a primary fuel pump before the high pressure pump, it is rocked directly from the drive shaft (or manually with a little lever), and as such is in the oil pan.

Our had a pin prick hole in diaphragm that not only added oil to the fuel, but fuel to the oil.

Symptoms were exactly as described. Cleaned exhaust manifold, replaced injectors, etc. before discovering this.

I had this, that's why I changed the bleed pump, this helped to get it to run on low rpm...

[Quebramar]

Originally Posted by ramblinrod

White smoke is water (no sweet smell is fresh, sweat smell if coolant).

Blue smoke is oil (if no leaks and oil is down a litre on 50 hours is confirmed

rings or valve guides).

Black smoke is unburned fuel (if high RPM, overloaded, if low to normal cruise

RPM injectors need service (most likely) valves need adjusting (second) injector timing off (third).

Very instructive. Where would grey smoke come from? Mixture of black and white?!? Thanks

[GordMay]

Greetings and welcome aboard the CF, rweike.

[davil]

skatun

please post what the problem was after you found it.
Is very helpful to learn what and the solution.
thanks
David

[mrohr]

ck the simplest first. My yanny started showing black smoke...found piece of insulation sucked into air intake...pulled it out problem solved in 5 min. no tools needed.


.............luv you all......mike

[Compass790]

Originally Posted by skatun

I did clean and test opening pressure of injectors, hopefully this weekend I will do the compression test.

I forgot about exhaust elbow & air intake too. Hell there are a lotta things that can cause it all these posts remind us. Exhaust elbow design kills more Yammers than anything else apart from lack of maintenance I suspect. Can't wait to hear what solves your problem.

[skatun]

Yesterday I got my hands on the compression tool!

So one cylinder has 14.5bar in compression, the other one 0 bar. I could see one nozzle being dry(working one, the other one wet. So I guess its time to pull the head off, any tips how to do this?

[Captsteve53]

Best tip: watch this short video on 2gm cylinder head removal

https://www.youtube.com/watch?v=qp056LYvdRc

[skatun]

Originally Posted by Captsteve53

Best tip: watch this short video on 2gm cylinder head removal

In the video it says you should loosen the head bolts in a spesfic order, what is the order?

[sailah]

Before you pull the head do a quick valve lash check. Simple to do with valve cover off. If you have no compression the two most obvious candidates are bad or broken rings, in which case I'd expect you'd be burning oil and the smoke would be blue. Or you have valves that aren't sealing, which means you have no compression with a test, but while running the clearance might be slight and with the speed of an engine, could compress the fuel mixture in the bore enough for a slight burn, which means black smoke.

I had an issue with my Westerbeke where an intake valve was stuck open from ingesting a piece of filter. Made lots of black smoke. But the point was I did a valve check before removing cylinder head and the problem valve was immediately apparent before removing the head.

The fix was to bring the head to a machine shop and they vacuum tested the valves. 2 needed a little work so they recut the whole head and lapped everything proper. New seals and I reinstalled with a new head gasket. Its a fair amount of work going that deep into the engine.

[Captsteve53]

Actually the video has a few erroneous statements i noted when i watched it,

1) Undoing the cylinder head bolts can be done in any order

2) When replacing they must follow a certain pattern usually shown in the repair manual and be usually torqued in a series of three movements , the pattern is basically starting with the center bolts and working to the outer bolts in a systematic order three times around increasing the torgue each time
3) Replacing the cylinder gasket is a MUST DO (in the video he referenced may be use the old gasket!!)(not possible)
4) Most modern cylinder head gaskets are fitted dry(no grease/no sealant/no oil)

Cheers Steve