leaky exaust gaskets

[swampy2646]

Re-powered this year with a 2009 350 mag. mpi mercruiser. runs sweet, but i blew my starbord side exaust manifold in june. this week the port side went! what gives? anyone have this problem? of course they were under waranty, but still..................?

 

[littlebookworm]

Re: leaky exaust gaskets

What brand exhaust manifolds did you buy? There have been a few threads on this kind of problem. Many after-market manifolds have mating surfaces which aren't perfectly flat. The recommendation is to draw a flat file across the mating surfaces to remove any casting slag or imperfections which may have been left by the factory. Then, after the first day's run, retorque the mounting bolts. Then you should be fine. Hy

 

[Fishermark]

Re: leaky exaust gaskets

i blew my starbord side exaust manifold in june. this week the port side went! what gives?

What gasket did you blow? The gasket between the head and the manifold, or the manifold and the riser? I would suspect improper torque or perhaps cheap gaskets. Buy some good gaskets and torque to specs - then, as mentioned above, re-torque after running and it cools.

 

[swampy2646]

Re: leaky exaust gaskets

this is a brand new engine with 50 hrs on it!

 

[Fishermark]

Re: leaky exaust gaskets

this is a brand new engine with 50 hrs on it!

I guess I took it to mean you repowered with a new engine and reused your manifolds and installed them yourself. So this was a complete bobtail engine? You still haven't said which gaskets blew. It is unusual for them to fail. Maybe they were installed on "hangover Monday."

 

[swampy2646]

Re: leaky exaust gaskets

yeah, this is a complete new power package. when i say manifold gasket i assume its the one between the head and the manifold, i would call the other one the riser gasket. the only time i ever had to change the gaskets over the years that i've owned boats, is when i replaced the manifolds themselves. its strange to have both go bad on a brand new engine.

 

[OldNBold51]

Re: leaky exaust gaskets

New Exhaust manifold gaskets shrink with heat. My new ones started leaking even though i torqued them to spec. All the exhaust and intake bolts on both sides of engine were loose over a period of about 30 hrs.

Tighten yours and see if leak goes away. Check your intake as well.