Black smoke on yanmar diesel

[Qayaq]

Hi. The Conrods in those engines are quite bendy. If the bigend damage was caused by hydraulic lock or similiar it might of affected the piston height at TDC. so a good idea either get the Rod checked or mearsure piston height to block deck when you get it back in. Good luck.

[skatun]

I got the Pistons back in yesterday, the big end hole had an noncircularity of 5/100mm, same for both pistons. This Sunday I will put the top and oil dump lid back on and hopefully start it again.

The motor mounts are in pretty bad shape, original cost like 200usd per piece, is there any cheaper alternatives?

[NYSail]

Think you should check your mixing elbow..... a buildup of coke from engine where cooling water and hot exhaust meet blocks exhaust exist. Yanmar recommends replacement every 500 hours on some models. One my old engine I replaced when first bought boat and then 8 years later started noticing black smoke...... took it off and it was 50 percent blocked on the exhaust side. Water side was clean. Replaced and no more black smoke.
Good luck!

[skatun]

Yesterday I started the engine after doing this:

• Changed all filters
• Changed all hoses
• Changed all sink anodes
• Refurbished valve seat
• Adjusted valve clearance(0.2mm)
• Replaced big end bearings
• New top,oil pan, exhaust manifold,water inlet/outlet gaskets
• Replaced all banjo gaskets and two banjo bolts to stainless steel
• Refurbished starter
• New 105A alternator
• New bleed pump
• Compression test
• Valve opening pressure test

And it runs without hammering sound, however it seems to still not want to idle properly. So what I noticed is that its seems like the injector pump delivers more fuel on the rear one. And there are hint of black smoke..

So what i were wondering is if the the o-rings inside the injection pump has wear on them? And is it simple to check these?

I uploaded videos and photos here

[tjandoverguy]

i changed the prop from a 16 13 to a 14 9
no more smoke
the engine was overloaded
ran it for 3.5 hours ,no wind, no problem

[sleaper]

Skatun :

This sounds like an electrical problem to me. Yes. Strange right. But then again.

I recently had an engine issue following a splash after maintenance. We know the engines are good. But on starting, black smoke and almost no throttle response. Turns out the battery selector switch was not fully engaged. It was the first thing I thought about, rather than mechanical, because the engine was working fine and no work had been completed other than a cleaning of the water system.

Could be worth checking out.

Check ground, check battery cables, check any selectors, keep an open mind.

Good luck. I'm new to big diesels so could be completely wrong.. which is OK too, but thought I'd offer up something .. if anything at all.

You can see in my splash video here (timelapse) the stbd engine start and chuck out a tonne of black smoke at the 30 second mark.

https://www.youtube.com/watch?v=_F6c-VY0XFA

[skatun]

The 2gm20 runs without battery so its definitely not an electric problem, you probably have electrical pumps which are simpler and better and why most new engines uses this.

I think its either internal leakage in the injection pump that reduces the outflow, most likely 1 of the o-rings in the injection pump or some dirt clogging the 1 out port. It could also be the timing of the pump, but I doubt that would affect the flow, but rather the time its spits out fuel.

[Sailmonkey]

Originally Posted by skatun

The 2gm20 runs without battery so its definitely not an electric problem, you probably have electrical pumps which are simpler and better and why most new engines uses this.



I think its either internal leakage in the injection pump that reduces the outflow, most likely 1 of the o-rings in the injection pump or some dirt clogging the 1 out port. It could also be the timing of the pump, but I doubt that would affect the flow, but rather the time its spits out fuel.

The injection pump plumbers themselves have no seals of any kind.

A test. With the engine running, loosen the nut on the forward injector fuel pipe and see if the engine speed changes. Then repeat with the aft one after tightening the forward one.

If the speed does not change when you loosen the fwd nut, but the engine stalls or noticeably changes speed with the aft nut loose, the problem is either the injector or the pump.

A cheap verification of injector or pump is to swap the injectors into the other cylinder and repeat. If the results are the same, the pump needs service.

You cannot service the pump unless it’s something simple like the delivery check valve. Otherwise the tolerances are too fine for mere mortals to work on.

[skatun]

Originally Posted by Sailmonkey

The injection pump plumbers themselves have no seals of any kind.

So number 6 & 13 is not a seal?

I will do the test as you suggested though, I was a bit worried to swap pistons due to timing, but if you say thats not an issue then I will try it.

[Sailmonkey]

Originally Posted by skatun

So number 6 & 13 is not a seal?



I will do the test as you suggested though, I was a bit worried to swap pistons due to timing, but if you say thats not an issue then I will try it.

6&13 are seals, but not ones that will reduce the flow to the injector, if they were bad you would have fuel around the top of the pump.

When you swap injectors you’re not attaching one line to the other injector without first putting the injector into the other cylinder.

Do not swap the fuel lines!! You must leave the hard fuel line for the aft cylinder attached to the aft cylinder.

The injector from the fwd cylinder can go into the aft cylinder without any problems though.

[skatun]

Originally Posted by Sailmonkey

6&13 are seals, but not ones that will reduce the flow to the injector, if they were bad you would have fuel around the top of the pump.

OK, so which seals can lead to internal leakage or where can particle be stuck in the pump?

I will do all the test that you suggested this evening.

[Sailmonkey]

Originally Posted by skatun

OK, so which seals can lead to internal leakage or where can particle be stuck in the pump?

I will do all the test that you suggested this evening.

parts group 7 is the fuel deliver check valve. If spring 11 is broken, or if the poppet is stuck, then the pump will have trouble delivering fuel. The plunger and body set, part 3 has no seals within it, the two parts are machined as a matched set, the plunger having a clearance measured in microns to the body.

so if only one of the plungers is not developing pressure for the injector, and you are not leaking fuel into your crankcase, the culprits can be a stuck check valve, or a plunger that is not fully retracting with the cam follower. IF the former, you can have a go at cleaning or repairing the check valve. If the latter, you can give a gentle tap to the plunger with the check valve assembly removed, but if there is any grit in there, the pump will need a rebuild. These pumps are not tolerant of fine particles in the fuel.

[skatun]

So, the engine is back in the boat. unfortnately it is just running on one sylinder. I did swap the injectors around with no effect, the front cylinder is not running. When i got it running i loosen the fuel line to the injector, with the rear cylinder it died instantly, but the front one no effect.

I also swapped the top part of the injection pump around without any effect. Also when bleeding the engine, there is hardly any diesel coming out of the front outlet of the injection pump. So I guess the injection pump is broken

I have pulled it out, but now comes the question where to get it serviced or get a new one. I am flying to Connecticut and Ohio next week and have been considering bringing it in my carry on luggage. Is there somewhere over there where it can be serviced or is it possible to get a new/refurbished one somewhere in the USA?

[Captndave1]

Possible injection could be too far advanced. I had that problem.

[skatun]

Ok, would that effect only one cylinder? And how to check it?