white smoking diesel engine after winter maintenance

[vasant]

Hi all
So here we are , just launched the boat after winter maintenance.
This included of course typical engine maintenance for the old MD7A, that is changes both fuel filters, cleaned air filter, cleaned lift pump strainer, changed oil and oil filter. Of course engine started after several attempts to purge air from the fuel system.
Now on the first travel during a warm day engine operated for 3 hours. Everything was as before EXCEPT that there was increased white smoke emission.
2 months before the exhaust was almost clear at least after warm up.
No other observation engine started and runs fine.
I tend to believe that after some longer operation this might settle although i would like to check it as well during the weekend. Could it be that the system needs to be vented further? Cannot think of anything else (impeller changed in summer, water flow was normal)
Cheers

 

[paulajayne]

Was engine temp in normal range?

Ambient conditions can effect visibility of exhaust gases.

 

[vasant]

Thanks,
I would say yes in 3 hrs the engine was hot and the day was sunny at about 15-20degrees...

 

[Malish]

Might be teaching you to suck eggs but:

Did you use the same oil as previous, not a nice flashy modern 5W30 or similar?
Is there a breather on the crank case (afraid I don't know the specific engine), is it blocked with oily emulsion or the pipe kinked?
Are you sure it is smoke (un burnt diesel or oil) and not steam?

 

[vasant]

Thanks for considering.

Might be teaching you to suck eggs but:

Did you use the same oil as previous, not a nice flashy modern 5W30 or similar?
VAS: No plain 15/40 only mineral
Is there a breather on the crank case (afraid I don't know the specific engine), is it blocked with oily emulsion or the pipe kinked?
VAS: yes there is one connecting to air filter. i think it was ok, but i could double check. In any case lack of air would create black smoke i guess...

Are you sure it is smoke (un burnt diesel or oil) and not steam?
VAS: Not really, but steam would also come with restricted water flow, no? Smoke looks heavy it doesnt really rise and dissipates fast.

 

[rotrax]

A pretty basic rule of thumb for old generation diesel engines is that white smoke often indicates leaking injector nozzles.

Testing is not too expensive.

Are you sure it is white smoke and not steam?

Our Bukh DV20 has steam-or at least water vapour-in the exhaust once warmed up.

When the injector nozzles were defective, it had serious white smoke at all times, and was hard to start and would not idle.

 

[Skylark]

General guidance is that black smoke is poor or incomplete combustion, blue is lube oil burning and white can be either raw diesel or water vapour.

There are many cause for each so a bit of detective work is normally required.

 

[vasant]

update
went today to check the issue further and guess what , the engine didnt start.
My suspicion so was true and it took another longer round of bleeding the system in particular the high pressure pump and the injectors until it started.
I suspect that i had not fasten the bleeding screw at the primary filter enough. Anyway after it started i bled again the injectors one by one during operation and it seems now sorted.
One thing that made an impression is that the pressure on the one injector line was feeling much more "vivid" that is like a heartbeat really. The other, ok there was just diesel comming.....
Thanks all for your suggestions

 

[rotrax]

update
went today to check the issue further and guess what , the engine didnt start.
My suspicion so was true and it took another longer round of bleeding the system in particular the high pressure pump and the injectors until it started.
I suspect that i had not fasten the bleeding screw at the primary filter enough. Anyway after it started i bled again the injectors one by one during operation and it seems now sorted.
One thing that made an impression is that the pressure on the one injector line was feeling much more "vivid" that is like a heartbeat really. The other, ok there was just diesel comming.....
Thanks all for your suggestions

Sounds like leaking injector nozzles-the leaky one not allowing full pressure to develop.

Get them tested...........................

 

[vasant]

Thanks. Again today the system had air in it and refused to crank.
So i guess i must have messed up something.
one thing of course is the primary filter that could be not seated well. But i removed also the top of the lift pump to clean the strainer and i suspect the gasget didnt like that. Its hard to find a replacement service set for those pumps, so i left the gasget in place. ALso the garget of the screw on top might have failed. So it seems i need to have a closer look on the lift pump

 

[pandos]

I had similar last year. I think it was caused by old fuel
I ran mine on a gallon of fresh fuel and it was clear after a little while....

Might be worth a try...

 

[vasant]

thanks, no this is not my case. I have fresh fuel and tank cleaned as well.

I am now almost certain that the old pump was sealing well with all the paint etc. It took some effort to remove the dome so i believe it didnt seal well as i used the same (old) flange

 

[vasant]

flange of primary filter was found crumbled.....
Lets seee