Exhuast Manifold Gaskets

Hello! Somebody had the exhaust manifolds off in the early 80s on my '70 GTX. They used header gaskets when they put it back toget5her. I want to remove to exhaust manifolds because the gaskets are leaking. What kind of headaches am I going to occur?

What would be the first step to getting them off? Do I need to heat the bolts? Or do I just spray them down with WD-40? Also, what type of gaskets should I replace them with? Any ideas or information would be appreciated. Thanks!

I'm a SB guy but I think all BB ex bolt holes are wet so drain the coolant down (2 gallons oughta be plenty). No heat, just a breaker bar & give it a good bump to shock em loose.

PB-Blaster or Aero-Kroil on the fasteners would be my first step.

^^^ agreed, if these are exposed threads/nuts then spray em/let em soak for a day. you dont want to snap any studs

Do you have an H pipe? If so you will need to remove the nuts and bolts holding the pipes on to the manifolds. These usually don't come off without heat first. Wire brush the exposed ends of the bolts, heat them to a dull orange, let them cool a few minutes and then remove the nuts.

If you don't have an H pipe you might be able to change the block gaskets and leave the pipe on the manifold which will save a step.

Next is the manifold to block hardware. First use a wire brush on the studs that are sticking out past the nuts and clean off the threads remove the crust. Usually the studs will not come out of the head, yes there is coolant behind all of the studs.

Put the WD40 away and use a better penetrant as listed above.

I use Fel-Pro exhaust manifold gaskets. The pipe gaskets that come with them are the wrong size so order the larger 2.5" flange gaskets separately. If you have any pitting in the flanges the muffler paste can assist in sealing the gaskets. Follow directions on the package.

Depending on the length of the studs you may have to remove some or tilt the motor to one side to get the manifolds off. If any of the studs do come out it will dump coolant, so be prepared. I would even recommend getting a stud and nut kit, replace them all and use sealant on the head side of the studs and anti-seize on the manifold side.

Don't replace them all because it will be a huge fight with engine in the car. If they stay in then clean and reuse them. 3/8" studs are pretty tough. Use anti seize compound on them before going back together.

Make sure the manifolds are flat when you remove them. If they are warped,which the usually are, take them to the machine shop to get get them mill. Then they should not need gaskets.

agree, no gaskets should be needed. however, a thin smear of high temperature RTV can help if the manifolds are flat, but have a few shallow pin holes or pockmarks on the surface.