Unburnt fuel in exhaust?

[l'escargot]

First longish motor of season - revs OK, power OK, exhaust appears normal but noticed some "specking" of what appears to be diesel on surface from exhaust. Not a huge amount but present at start up and an hour or so later when engine switched off. No black smoke, doesn't look like oil and no other indication of any problems. Should I be investigating or just waiting to see if it goes away?

 

[hlb]

I get it all the time, especially at start up, It dont worry me.

 

[oldharry]

Did the engine need much cranking before it fired up the first time after lay-up? If so the exhaust is soaked in diesel, and it will take some time to clear.

 

[saltwater_gypsy]

If an injector is not producing a uniform fine mist then any fuel droplets may come through as unburnt fuel. When were the injectors last checked out?

 

[Piers]

Unburnt fuel makes exhaust brown/black. I have been told that diesel from the exhaust can indicate a faulty turbo seal, but how accurate that last comment is, I don't know.

Piers

 

[kandoma]

if you have a Volvo Penta engine, all is fine and you have another 10000 hours of smooth running in front of you. As soon as the Volvo Penta stops oiling, you better start worrying.
All other engines may have a problem, ranging from glazing, faulty injectors, lost O-ring on the oil dipstick or just a dirty air intake.
Difficult to say from far away. It may be engine oil, not diesel fuel.

Peter

 

[l'escargot]

It's a 1968 Perkins 4107, so not Volvo and no turbo. Pretty sure it's not engine oil as there are no other symptons.

Have had starting problems (poor cranking - new battery, earths cleaned up and starter motor coming out for a once over next) so I favour the diesel in the exhaust option at the present, with checking the injectors as a second option as I don't know when they were last checked.

Think I will just watch for a few hours and see if it continues or goes away. Thanks all.

 

[starboard]

Unburnt fuel entering the exhaust......try reducing revs slightly till traces stop appearing........you will find the engine will only reach a certain RPM and then no matter how much throttle you give it the size of the prop will stop any further increase and therefore any increase in injected fuel will be exhausted unburnt!!

Paul.

 

[l'escargot]

Only trouble is I'm getting traces at tickover so can't reduce revs anymore.

 

[FlorealIII]

We had the same problem on a Volvo MD22L and discovered a wrong timing at the diesel pump . After reconfiguring the correct timing the problem was solved .