Ok, my son has a 99 STS and the head gaskets went. On the rear head all head bolts snapped loose upon removal. (Front not yet pulled, figured rear would be the worse due to heat. Gasket bunching evident.) So far looks like no coolant made it to the head bolt threads so I suspect we may not have the “gray dust of death” when we drill and tap for inserts. None were mushy. We have, the following kits M11-1.5 time-sert, M11-1.5Big-sert and M11-2.0 time-sert.
So the coarse thread gets a better bite into the aluminum and GM does not warranty the Big-serts. So I am leaning toward the M11-2.0 inserts. The engine came out the top due to lack of facilities, so we want to do this once and do not want to go back. The gasket kit that will be used is Felpro.
To be able to utilize the M11-2.0 inserts, what bolts do I purchase? I believe the later engines used two different lengths of head bolts. Are the LSx bolts the same length as the ’97-’99 Northstar? If so I would just purchase 3 sets of LSx bolts and be set.
Thanks
STS Tom
: