Why do I keep blowing exhaust gaskets?

[clarkedj]

I replaced the exhaust gasket on my sons 78 124 spider about 2 weeks ago. We blew the gasket again 3 days ago. I replaced the gasket and tightened to 18 Ft/lbs whch is the recommended torque. Any ideas what may be causing the back pressure. I replaced the exhaust sytem about a year ago and had a custom job doen on the exhaust. Any ideas?

Thanks

Ed Clark

404-234-7366

[124JOE]

my headder leaked for years
this year i wraped my headder,when i removed it i seen that the gasket wasnt seating corectly.
so i used a rat tail file to move the gasket up about an 1/8 to 3/16 higher.
i had ordered a new gasket but by the time it arived i had it sealed joe

[manoa matt]

What type of gaskets are you using? There are simple fiber/paper gaskets, there are also fiber gaskets that have metal reinforced fire rings around the ports, similar in construction to a head gasket.

Some ultra high temp copper sensor safe RTV silicone on both sides should help seal it up, just make sure the surfaces are free from any latent oils and solvents prior to application. Wipe the surfaces down with brake parts cleaner or acetone.

[majicwrench]

Headers or a stock manifold??

I don't like sealer. If a manifold and you are blowing gaskets it is because something is warped.
If it is headers and it is blowing gaskets good luck. Headers are, IMHO a huge waste of time and energy.

[azruss]

very easy to warp the headers. find a nice flat surface like the steel table on a table saw. get some sticky-back sandpaper and stick it to the table. now run the gasket face across the sandpaper in long slow strokes. you will be able to see right away if you have a warp issue.

[124JOE]

my headder was and is still flat.but the ports didnt match up.so i raized the gasket to fit better.
the headder did raise under hood temps,thats what the wrap is for.joe

[131]

What type of gaskets are you using? There are simple fiber/paper gaskets, there are also fiber gaskets that have metal reinforced fire rings around the ports, similar in construction to a head gasket.

Some ultra high temp copper sensor safe RTV silicone on both sides should help seal it up, just make sure the surfaces are free from any latent oils and solvents prior to application. Wipe the surfaces down with brake parts cleaner or acetone.

I always use the gaskets with fire rings, as well as a high temp exhaust sealant, make sure surfaces are cleaned with solvent and allow sealant time to cure before starting the engine.