BBF Exhaust manifold issue

[Keithb87]

Newbie Mike and I took his new boat out to the lake to test it. We took the time to change the exhaust manifold gasket on the left bank. after a few runs at te lake and back on the trailer.we noticed that the new gasket was blown out in the same place that the old one blew out.
What should we do?

[Keithb87]

I was thinking about doubling up the gasket on that side, or should we find a thicker gasket than the Felpro that we used this time.

[akjet]

sounds to me like manifold or head is warped and needs to be surfaced by a machine shop had same problem and once surfaced never had any more problems

[rerfert]

sounds to me like manifold or head is warped and needs to be surfaced by a machine shop had same problem and once surfaced never had any more problems
My money is on the exhaust...Might just be in the flange area(check it with a straight edge)I have trued them up with a belt sander.
The double gaskets might do the trick also(put some copper spray gasket on the surfaces(especially where it burnt thru)

[Keithb87]

ttt any other suggestions ? :confused:

[Mighty Thor]

ttt any other suggestions ? :confused:
Tighten the bolts more. Actually, if the manifolds are like mine with only one bolt per cylinder you have to make sure everything is flat and properly tight and also that the exhaust hose does not put any pressure on the manifold in terms of trying to pry it away from the engine.

[058]

The manifold is warpped and needs to be machined. Do not run gaskets with aluminum ex. manifolds. A thin coat of high temp silicone is all thats needed to keep it from leaking and no gasket will prevent it from warping.

[hack job]

The manifold is warpped and needs to be machined. Do not run gaskets with aluminum ex. manifolds. A thin coat of high temp silicone is all thats needed to keep it from leaking and no gasket will prevent it from warping.
yup
;)

[Keithb87]

Ok. We tried the copper gasket material with a gasket and I just checked it again and it's blown in the same place. :2purples:
I guess we need to check the log for straightness at the exhaust port?
Or should we use more copper gasket?
Is this common on a 460 with logs?

[Oldsquirt]

Yes, you absolutely need to check it for flatness across the entire length of the mounting flange. Take a close look at the area where the gasket blew. Are there any nicks, cracks, gouges, low spots? Unless it is near perfect, you need to resurface it. Check the cylinder head as well.
As mentioned above, with both surfaces flat you only need a thin film of high temp silicone to seal. No gasket.

[Keithb87]

Thanks. I'll pull it and look at it tonight or tomorrow.
Is it possible that the Manifold studs are warpped and not allowing the manifold to properly seat on the head? Should I replace the Studs and nuts? :confused:

[87 rogers]

save your self the trouble and have the manifold surfaced or you will never get the manifold to seal for very long.