Removing the exhaust manifold can be a challenge if the bolts have been in for over 30 years. Bad luck if they break. But that means that you need to find a way to remove the studs and prepare for new bolts without damaging the aluminum engine cast.

This is a trick I saw on a forum. Thought I'd save it here to help others....

Trying to weld a M8 nut to the remaining stud failed every time. The solutio0n was this:

weld a little "hill" on the stud, so that a M10 nut does not go over it. Place the M10 nut so that it is flat with the remaining stud. Weld the top side so that the metal flows and fuses the parts.

The heat from welding and the fused M10 nut make it pretty easy to remove the remains of the broken bolt.

Fitting new bolts should be done with use of heat resistant lubrication like Optimoly TA

Theo

1992 928GTS midnight blue

The Netherlands