...I've jumped thru several post here about the infamous head gasket failure on these 3.0 v-6s and was wondering about something that I can't seem to find. Once I replace the headgasket, is it going to be prone to fail agian, or once it's replaced will it last? I'm not quite sure if the headgasket goes because of a design flaw in the motor or because of the actual gasket.

Could someone explain this to me.
Many thanks!

 

The gasket itself was bad. Around 1989, Toyota changed the headgasket to one without asbestos. This gasket was significantly weaker than the earlier version.

So, if you clean the mating surfaces correctly, use high quality gaskets, and either use new head bolts or ARP studs the headgasket should last a very long time.

 

Use the slipper-plate design gaskets from Rock Gasket, Toyota (dealer) or engnbldr.com. It's also important to keep the cooling system in good working order (radiator, fan, shroud, 50/50 coolant/ water mix, etc.). Also check to make sure your cat isn't clogged and creating excess exhaust backpressure against the manifolds. Number 5 and number 6 exhaust valves are the ones prone to burning and that's where the HG usually fail , as well.

Mike in AR

 

Poor factory crossover resulting in high heat retention can be eliminated with the addition of headers. Might even gain a few HP... but I wouldn't worry about holding on to your seat.