Hi, I was wondering what causes the headgaskets to blow and at what miles does it usually happen? Thanks.

Usually the head bolt threads pull. There is no "usual" mileage. Some go at 75K or so. Others are still good at 250K. Pre 2000's are more prone to failure though. Keeping up with the cooling system maintenance may help.

This is my theory. I have more to add.

http://www.cadillacforums.com/forums/northstar-performance-technical-discussion/133429-root-cause-head-gasket-failure-fix.html

I am pretty sure that AJ is spot on in his theory. I have a bit of one myself, I have rarely seen them blow in the south where it's warmer, mostly in the northern, colder states. I am thinking that quick cool downs from being hot might have some effect on it, but I have no proof.

the starving children of Nigeria cause it...

in all seriousness many things:
lack of coolant care
pulled head bolts
weak shotty aluminum casting

the starving children of Nigeria cause it...




That's a cop out...we all know it's a combination of global warming on a global scale and George Bush's fault! :nyanya:

I have blown head gaskets in two separate '97 engines in AZ, and that is about as far South and hot as it gets