SailNet Community banner

1 - 5 of 5 Posts

·
Registered
Joined
·
15 Posts
Discussion Starter #1
I have a 1991 Yanmar 24hp diesel in our sloop with approx 800 to 1000 hrs. After sitting idle for a day or more, on startup, it sputters and emits blue smoke for a bit before it finally smooths out, to run great for the rest of the day.
I have poked into the water cooled exhaust riser and it seems to be clear. The fuel is clean and the engine runs normally cool and is very strong.
I''m new to diesels and would welcome advice on cause and cure.
 

·
Registered
Joined
·
1,000 Posts
It could be that the bluish smoke that you are seeing is a result of some oil leakage past the valve guides or piston rings. Or, one other possibility....is your engine crankcase filled with the proper oil and viscosity for your area?

If you are not certain what kind of oil is in the engine...drain the oil and replace it and the filter with Shell Rotella T 20W50 or Chevron Delo 20W50, if you are are in the south or tropics. If you are up north use 10W40.

The bluish smoke that you are seeing is oil burn...not diesel fuel. A cold diesel puts out blackish smoke and as soon as the pistons and combustion chamber heat up the colored smoke dimishes as the diesel burns more completely. The bluish smoke dissapearing means that the lube oil in the combustion chamber is gone.

If changing the oil does not solve the problem....then it is possible that you need to have a mechanic look at it. But, if you are only getting "a little bit of blue smoke", I wouldn''t be too concerned. If its belching large clouds of blue smoke and stumbling and running erratic....thats different.
 

·
Registered
Joined
·
5,067 Posts
Agree totally with oil burning.... probably from bypassing/leaking past a valve seal. Such stuations possibly indicate a leaky water manifold.... draining/leaking cooling water back into the combustion chamber. I sincerely recommend that you check the exhaust manifold and downstream piping for a pinhole water leak.
 

·
Registered
Joined
·
15 Posts
Discussion Starter #4
Thanks for the information.
I checked the oil used. It is Texaco URSA Super Plus SAE 30. The boat is in New England. I checked the oil consumption closely and there is a small amount being consumed that could be consistant with a leaking valve seal.
I put an injector cleaner in the fuel and the smoking seems to be decreasing on startup. Is it possible that dirty injectors are leaking?
How should I go about checking if the water cooled manifold has a pinhole leak into the engine? That one really sounds serious!
There is no loss of antifreeze.
Will
 

·
Registered
Joined
·
1,000 Posts
I believe that test is done by removing the radiator cap and putting a pressure pump with a guage in its place and pumping it up to a #of lbs of pressure and seeing if the pressure drops over a certain period of time.
This would indicate a leak somewhere in the system.
 
1 - 5 of 5 Posts
Top