When to change the headgasket?
 

About how many miles should this be done or do you just change it if you have the head off and if it pops?

I don't know that I have ever had a customer just want me to do a headgasket as preventative maintenance (well maybe one or two), most just wait until it lets go. IMHO the cars are 25 years old, if it hasn't been done, it probably should be done. Best to couple it with a timing belt job or cam tower reseal or something so some of the labor crosses over.

Definitely before you do any mods that will increase boost...

Given nothing else is changing, there's no compelling reason to replace the head gasket unless it has failed.

As Matt said, it might make sense as part of a refresh before doing higher hp mods that will put more stress on the hg seal. And as Doc said, it might make sense if the cam tower needs to come off for other unrelated work. Both of these are potential 'reasons' but both assume that something else is changing.

This is one case where 'if its not broke, don't fix it' is good advice.

I've never just wanted to change the head gasket, PITA job

I also feel its a good idea to do it if its never been done before. Easier to do it while its not leaking and at your own time than have it go when your on a trip or need to be somewhere. My n/a went at about 75k miles if i remember right, but the headgasket was also about 20 years old at the time. My turbo i did at 100k miles and it was about 21 years old or so. The n/a gasket had ate through the fiber material and coolant had split the fire ring in two. My turbo gasket had the same holes going through the gasket and was probably going to do the same thing within a fairly short time period.

the fact that your asking you should change it. serisously

I used to own a neon. It popped 3 headgaskets in the first 36,000 miles when we owned it that was due to not using a MLS headgasket(still will never understand why no one does this). I was just curious.

oh wow dam. get the cometic head gasket.

Do they make MLS headgaskets for the 944? I'm guessing not since its an all aluminum motor.

yes they do i have one

I dont see the point in going for a COMETIC gasket unless the top is resurfaced and you are sure everything is level, . I use the Widefire "CUP" one and it has taken the worst kind of abuse for 2 years with very high boost levels. When the top came off it looked great. I also dont know why you would fix something that is not broken until it is.

This is my thinking. I am currently getting the timing belt and front end service done. The guy mentioned that i'm close to doing the top end.

It looks like I'm facing an impending head gasket job here. I'm really wishing I had just done the head gasket when I did the timing belt/front seals now. Don't forget the oil cooler while your in there too...

Head gasket materials will fail with age, just like other materials. If anyone has ever used coolant with phosphate in your car, it will fail sooner.

I would replace it just because of age, then you won't get stranded somewhere with a failed head gasket.