Exhaust header leak (can't get rid of it!)

[DrieStone]

My '92 Loyale sounded like a VW bug when I bought it. Looking underneath it's obvious that there was an exhaust leak on the driver's side head. Someone had replaced 3 of the exhaust studs with bolts as well. So I did what any good shadetree mechanic would do. I bought a new set of exhaust studs, a helicoil kit, and new gaskets. I buttoned everything up, but nope... still have the leak.

I bought a set of better (thicker metal) gaskets which I haven't put on yet, but I'm wondering what I can do to help the situation here. Can I double stack exhaust gaskets? Is there something else I can do outside of swapping the exhaust itself?

[DaveT]

Probably one of the flanges is out of plane.  

Those gaskets don't have a lot of give to take up slack.  

I make up my own gaskets now.  Layers of woven fibreglass with copper rtv worked into it.  Make at least 4 layers.  Goop them and stack them.  Use a gasket as a guide - you only need the rtv where the gasket will remain.  Set the goopy stack on a piece of aluminum foil.  Lay a second foil over the top.  Place the sandwich on a flat surface and lay a flat surface on top of it.  And weight it.  Give it a few days to set.

I also put thin spacers to prevent the weight from crushing the stack all the way down.  You need some give left.  About the thickness of the fibreglass layers resting dry.

 

Once set, leave the aluminum foil as part of it.  Cut out the gasket.

 

I've been running a set of these for quite a while  now, no leaks.

[Dee2]

Put a straight edge on the mating surfaces to see how big a problem you are dealing with or bolt them together without a gasket and measure the gap.

Edited November 13, 2018 by Dee2

[jono]

Any old silicon type both sides of gasket let set for a day and maybe use a torque wrench as well as check flat and squareness as said above. I love factory gaskets for the turbo engine in this location. Look for black sooty deposits for the leak