Excessive exhaust Mercruiser 357

[Ramanonos]

My Bayliner with a 5.7L mercruiser 357 carb is running great right now, but I've noticed it's spouting a lot of exhaust stream on idle (after warmed up). Maybe this is normal? It seems like much more exhaust than I'd expect to see from a truck with a similar engine. The engine is a relatively new factory referb. Any quick thoughts, or am I just being paranoid?

 

[oldman570]

Re: Excessive exhaust Mercruiser 357

Most all new or rebuilt motors will have some smoke when first used. They need a breakin to set the rings and should be run as so. The smoke should not be real excessive and should deminish as the rings and other parts get wore in an get a better seal. Treat it as if it were new, as it really is, and do the break in as reccomended by the rebuilder.

 

[Ramanonos]

Re: Excessive exhaust Mercruiser 357

Thanks. She has about 20 hours and I ran a good break-in RPM cycle. Just changed the break in oil, which was pretty low. Any oil burn going on with all that exhaust?

 

[Failproof]

Re: Excessive exhaust Mercruiser 357

Yep. New and rebuilt have a period of break in that uses more oil, (it gets by the rings), untill the rings start to mate and seal. Thats why you should ALWAYS check oil often, and especially when NEW!

 

[Ramanonos]

Re: Excessive exhaust Mercruiser 357

Thanks! As always, this is a great resource.