general head gasket questions

Ive been looking around to buy an mkiii supra, but i have some general head gasket questions. I heard the head gasket blows at roughly 70k miles, is this true? how much would it cost to put a new one on? Have you retorque it on a car that it hasnt blown yet? how exactly does it blow, and can you still drive it when it blows? Ive seen a few cars with 50k miles on them, but they still have the stock head gasket and im afraid to buy because i dont know when its going to go. shoudl i just buy a car that the gasket has already been replaced? thanx

There is no set milage for when the HG goes poof, it all depends on the cars history, maintanence, and mods. Some turbo MKIII owners are still on the stock HG with 200K miles, stock engine of coarse. N/A's generally have much less problem with blowing the gasket because they have less HP, owners tend to rag on them less because of it. The HG blows because Toyota slipped up and only torqued the head bolts to 55ft lbs, when they should have been 72ft lbs. This combined with the composite HG, alum head, and iron block all expanding at different rates is bad news, and NO, NEVER drive an MKIII when you know it has BHG. A retorque is a risky procedure, on the one hand your engine could last alot longer if its done right and at the right time (way before ANY signs of BHG). On the other hand some say it could cause your HG to go faster by disturbing it, besides if the HG is starting to go there's not stopping it. I personally wouldn't buy a MKIII with a HG job unless I knew exactly how it was done, a bad HG job can blow just as easy as the 200K mile stocker. In any case a HG job will cost about $400-600 depending on whats done, what parts are used, and how much machine work is needed. It will also depend if you get a stock composite HG or a Metal head gasket.

would $600 be for a metal head gasket and if I do the work myself? I dont mind paying $600 is the gasket goes, i was just real worried because I heard estimates of easily $1000. if i was to put on a metal head gasket myself, is it that difficult? i know that you have to have someone machine the parts for you, but i heard that putting it on is easy, even for someone with limited mechanical experience. all you need is a torque wrench and you take off the top of the engine and just switch the gasket. i know some people who have done work like thsi before, but with there help and a torque wrench should if be much of a problem to change?

If you go with a MHG the head and block will have to be VERY smooth, I don't remember the exact RA but any good machine shop will know. So if you go with a MHG this means your going to have to pull the block, and most likely dissasymble it to have it lapped. While the block is out you might as well rebuild the entire engine. You can lap the block by hand in the car but it takes FOREVER and the few that have done it would never think about it again. A composite HG is alittle more forgiving so the surfaces don't have to be as smooth, making the job cheaper of coarse. You can put the HG on and torque the head down (you will want to get ARP head studs or bolts by the way), but assymbling the internals and head you'll probably want to leave to the pro's. So it all depends on which HG you choose for your HP goals/driving style and who does the work, the price can change alot so just go out and get some quotes from local shops.