Exhaust keeps popping gaskets. Ideas?

[cornercase]

Hi all. I'm rocking a 2000 Expedition XLT with the 5.4 L engine. It's gotten a bit eaten up by the New England salt but I think I'm going to keep it around in spite of the rust. However, the passenger side exhaust gasket, cylinder 3 IIRC, has blown 3 times in the last two years. I'm trying to figure out a way to stop this short of pulling the head and planing the gasket surface. This truck suffered a passenger side 3/4 cylinder exhaust stud failure, to give you some context. Ever since I fixed it, the gaskets have held for a couple of months and then popped again.

I have heard that a small layer of roofer's tar on either side of the gasket will get it to hold, but I figured I'd see if there were other thoughts before I went and pulled everything apart again.

As a bonus question, I'm currently running a cheap POS header I bought off eBay which is going to get replaced when I do the gasket. Should I just run a stock mani or are do you have some suggestions for a header? It's got to be Cali-legal.

Thanks
Eamon

 

[flyin]

are you sure that the header surface to the head is flat? I would just pull the header and have it machined or go back to the stock manifold also, with a fresh surface.

 

[pooleo8]

Header or Manifold?

I just installed JBA headers on my ranger. The header actually has rasised ports where the manifold was flat. This was a problem with OEM gaskets. They "fell" off the back side of each port. The fix was to use Mr. Gasket header gasket material. I made my own gaskets.

Then, I used gold RTV, put a think layer on the header and "glued" the gaskets to the ports. No leaks now.