The exhaust manifold bolt on my 1994 xjs 4.0 snapped on me, on its own. I was able to drill the hole out and I tried to tap it. I got some thread going. I didnt want to go to far in in fears of hitting something so I only went in as far as the old bolt... Put a new bolt in and it worked for a week. Now its out again (the exhaust leak is loud when it is cold, like it was indicating a cracked bolt).

I need to drill farther in and try to tap out more thread or go with a larger bolt.

Does anyone know if I can tap in farther. I dont want to hit anything!

Recommendations appreciated. Is this a common thing? I first heard the leak a month ago and when popping the manifold I realized the broke bolt.

 

Try a helicoil of the correct size, Assuming you are talking about the head and that you didn't oversize the hole when you drilled the bolt out.

 

the hole is not oversized. The original sized bolt will grab. Its just not grabbing very good. if i could go in a 1/4" or so more and tap it, I would be confident in it holding. I just dont want ot hit a valve or something. Its the 5th bolt from left to right (first bolt on the right exhaust manifold).

my back up plan is a helicoil as you mention.

I managed to torque it at 17 foot pounds, so I will see if it holds. though, it seems to be spinning in place at 17 and not getting any tighter...

 

If it's spinning then the thread is kaput. I would definitely go for a helicoil as a first option.

 

I managed to get it to hold by tapping it a little farther in. Its been a couple weeks and all is ok.

When I removed the exhaust manifold there were three gaskets on both the front and rear manifolds. I am eventually going to replace the oil selas and head gasket, etc. The kit only comes with one gasket. Is there a reason why my car now has 3? Would going to 1 gasket cause leaks?

 

I hope this helps. I changed my exhaust manifold gaskets on my XJ6 about 3 weeks ago. When I took the rear gasket it out it looked like 3 were in there, but actually it was one that had come apart.

 

makes sense. It seems that when they make the gasket they press three thin slices of metal together. I didnt notice any glue so it must just be pressed.