Another Smoking & Cruising Question

[Dockhead]

Originally Posted by Chief Engineer

"White Smoke with a hint of blue indicates burned oil"

Page 43 Troubleshooting Marine Diesels Peter Compton

Page 408 of Calders' book goes into a little more detail...specifically redlining

Thank you so much. I am in Russia at the moment and have no access to these excellent books.

Starting to sound like blown turbo seal. What else does it say about redlining?

Cheers, Dockhead

[Chief Engineer]

They don't specifically refer to redlining.

But they do say do not race the engine at startup or shutdown. This will risk oil starvation.

If I were to give you an educated guess, the "running up" of the engine probably revealed a weakened seal or clogged oil return line (which may cause oil pressure to the turbo to leak past the seal)

Check the oil return line first.

[Dockhead]

Originally Posted by Chief Engineer

They don't specifically refer to redlining.

But they do say do not race the engine at startup or shutdown. This will risk oil starvation.

If I were to give you an educated guess, the "running up" of the engine probably revealed a weakened seal or clogged oil return line (which may cause oil pressure to the turbo to leak past the seal)

Check the oil return line first.

Thanks very much. That's a relief about redlining. I never race any engine, diesel or gasoline, at startup or shutdown. Since this particular boat has a turbocharger (our old one did not), I follow the usual turbo cool-off procedure to prevent coking of the turbine bearing (fast no-load idle for five minutes or so before shut-down).

This (Yanmar, 100hp) engine is rated at 3600 rpm continuous duty, and 3800 maximum. So at sea trial, with the approval of the engineer on board, after carefully warming it up, I ran it for a while at 3800 to give it a workout. Particular to check for any overheating tendencies, but also to reveal, I guess, just this sort of flaw.

I'll check the oil return line as you suggest. Thanks very much for the tip. I'll keep the Board informed how it turns out, so that this thread might be useful for someone else.

[Dockhead]

There is some news about this problem which may be useful to other Forumites. Also some new mysteries.

Well, the turbo and injection pump have been removed, sent off for service, and replaced. There was oil in the intercooler and so it seems that there was a blown turbo oil seal. The mechanics say that she smoked as usual on startup, but that after warming up the smoke disappeared.

They also said that the injection pump people found evidence of damage from water in the fuel. Furthermore, they said that the fuel filter was clogged. Seems odd, as I had the fuel polished and the tank was declared to have been in decent condition without any unusual amount of either water or dirt. The fuel looked nice in the transparent bowls of the brand new Racors I installed.

I suppose that the polishing process might have stirred up some dirt which didn't get removed by the process, but how could this reach the engine through a brand new Racor? At most, wouldn't a clog cause vacuum in the system and fuel starvation? I used the engine for 40-odd hours in this state, and never noticed any symptoms of fuel starvation; always started and ran perfectly, giving full power and running smoothly under all conditions (just very smoky).

Can dirty fuel, under such circumstances, cause smoking? What do you guys think?

Cheers, Dockhead

[Mark Zarley]

Remove cap that you pour oil into, while eng is idling. If it smokes like a chimney you have "blow by" , If it seems to puff it is probably just 1 cyl.

[Boracay]

I'm guessing that the water damage and the blocked filter were from a past life.

[Dockhead]

Well now both turbo and injection pump have been overhauled, everything put back together and -- smoke.

To sum up all the measures which have been taken:

1. injectors ultrasonically cleaned
2. control test run of the engine with brand new injectors
3. turbo overhauled.
4. Injection pump overhauled.
5. fuel was re-polished and Racor elements were changed.

WTF? There are no signs of low compression -- engine starts perfectly, gives full power, runs smoothly. Just smokes like a chimney.

Broken oil ring? Engine out on this boat is an unholy b***h.

[Chief Engineer]

Ok...we are back at square one.......


To sum up all the measures which have been taken:

1. injectors ultrasonically cleaned
2. control test run of the engine with brand new injectors
3. turbo overhauled.
4. Injection pump overhauled.
5. fuel was re-polished and Racor elements were changed.

Does the smoke persist after warm up?
How "old" is the mixing elbow?
Where is the boat? How cold is it there?
Check your shutdown cable/circuit.

Keep us posted my friend, we'll get to the bottom of it.

How is the oil level in the engine?

[Dockhead]

Originally Posted by Chief Engineer

Ok...we are back at square one.......


To sum up all the measures which have been taken:

1. injectors ultrasonically cleaned
2. control test run of the engine with brand new injectors
3. turbo overhauled.
4. Injection pump overhauled.
5. fuel was re-polished and Racor elements were changed.

Does the smoke persist after warm up?
How "old" is the mixing elbow?
Where is the boat? How cold is it there?
Check your shutdown cable/circuit.

Keep us posted my friend, we'll get to the bottom of it.

How is the oil level in the engine?

Back to square one indeed.

The smoke persists after warmup under load, but reduces.

Mixing elbow is original to the boat as far as I know (launched 2000).

Oil level seems ok -- no dramatic fall in level.

I am on the South coast of England -- temperature has been 10 to 23 degrees C during this whole drama -- so 40's to low '70's F.

I'll check the shutdown circuit. Other than a broken ring, I can't quite conceive what this is. If it were some big systematic problem with bores/rings, I would expect signs of compression problems (hard starting, uneven running, down on power) -- got none of those. Starts fine without glow plugs; runs great. Yikes.

[Chief Engineer]

Ther should be a hose running from the Valve Cover to the intake.....disconnect the hose from the air intake....start the engine......there is normally some internal pressure which will produce a small amount of vapour. If it is blowing out with force let me know and I will post the possible causes for that.

[Ex-Calif]

Need to get a good handle on the oil consumption to isolate once and for all that it is oil and not fuel. Based on the description I also vote that it is oil.

The only thing I have not heard questioned is exhaust valve guides. Oil past the exhaust lavle guides will go directly into the exhaust and would not affect engine performance in any other way and may or may not affect compression tests. It is however a very unusual failure mode.

[Chief Engineer]

Yes....failur of valve guide seals will cause a lot of crankcase pressure...which then goes into the intake and creates smoke...no real performance problem but lotsa smoke.

Same kind of smoke as an overfilled (engine oil) engine

[Dockhead]

Thanks a lot for the input, guys. So, if I understand right:

1. Check for blow-by. That would indicate bad rings or bores, right? Maybe a leak-down test too?

2. Might be valve guides. But this would be really unusual, wouldn't it? Remember the engine only has 870 hours, and the problem appeared suddenly. My experience with car engines is that valve guides are a kind of old-age disease; never heard of it as a sudden failure. But someone here suggested having the head off as the next step. Maybe there's something to it.

3. Oil level. Seems to be down about 1/3 between the high and low level lines on the dipstick, after something like 37 hours of running. I guess that's a good sign of oil burning.

[Chief Engineer]

We are not talking valve guides....but valve guide seals

I'll try to post a picture/diagram.

[Boracay]

Given some indications that a PO may have not treated the engine right is it not possible that the bores have glazed?

My (internet expert!) research suggests that a turbocharged engine idled for a long time with the wrong oil would be a likely candidate...