> -----Original Message-----
> From: owner-gmcmotorhome
> [mailto
wner-gmcmotorhome]On Behalf Of Dave
> Sent: Wednesday, May 19, 1999 9:19 AM
> To: gmcmotorhome
> Subject: Re: GMC: exhaust manifold gaskets
>
>
> >car craft magazine is advertising on p 10 header gaskets
> >thart are made of graphite and wont burn. made by
> >rol mfg 1-800-810-4067 i wonder how they work?
>
> My understanding is that the manifolds are the problem, not the gaskets.
> The manifolds get too hot and warp. I have heard from a number of sources
> that the best solution is to machine the warped manifold (to make the
> mating surface flat again) and then install it without a gasket.
> Use RTV to
> make the seal. The tight fit and the RTV conduct heat away from the
> manifolds (and into the heads) to keep them from warping.
>
> I don't know if this actually works. I would be interested in hearing how
> well it does work from anyone who has tried the no gasket/RTV approach. I
> suspect that it does add some additional load to the cooling system.
>
> I gave up on my manifolds (before I learned about this solution) and
> installed Thorley headers. The headers have thick gaskets to keep exhaust
> heat away from the heads. So far no problems after 10+ years.
>
> Dave
> 73 Sequoia
>
Dave, we think alike. I don't think you gave up on the original manifolds
too soon. After many attempts at replacing/machining exhaust manifolds (all
with no gaskets), including the last time, when I also machined the heads, I
switched to Thorley headers WITH a gasket. However, after one year, I did
have another small leak. This time, I replaced the "Ultra-Seal" gasket and
let the "High-Temp RED silicone Type 650" dry for the recommend 24 hours. I
also added the manifold bolts to my 60-day schedule to check for tightness
(joining the fan clutch, fan, and engine belts) So far, all is well. As
for longevity, I would be pleased if my headers LAST ten years.
Scott Shean
78 Royale
Baton Rouge, LA
