D
I'd say this is unlikely.suprageezer said:But when its full of collant and the system is working perfectly is it cavitating? thus causing hot spots that lead to BHGs'?
bigaaron said:The weakest link in the 7m is the stock headgasket, reguardless of who owns it.
You can quote me on that :rofl:
swaq said:You want to be quoted with a spelling error? :icon_razz
Nick M said:I have never ever seen a low mileage 7M headgasket just blow. You don't have to be low on coolant to over heat the engine either.
3p141592654 said:Look at these two pictures. You can see that the fire ring has gone egg shaped and the coolant passages crushed in. This is the classic failure mode. It is clearly related to the overall weakness of the gasket in the direction of the coolant passages.
Also note that the typical wear patterns on the block of a blown 7M show depressions of about 2 mil under the fire rings. This indicates that the fire rings are moving around probably due to the difference in expansion of iron/aluminum. As those grooves wear in, the force squeezing the fire rings is getting weaker and the movement will get worse. No amount of bolt tightening is going to save you at that point.
The MHG has two important advantages. First, the multi-layers slide on each other during the warm-up/ cool down cycles and prevents the fire ring grooves from forming, and the gasket is much stronger in the direction of the coolant passages.
By the way, my (purchased new) 90T showed signs of a BHG at 60k miles (gurgling, very slow loss of coolant, formations on plug #2). It finally blew big time at 110k miles (7 years after I knew it was going bad).
I changed the coolant every two years or so with red Toyota stuff, and this car has never overheated ever. The BHG is not related to any fundamental cooling issues. There was no coolant corrosion at all inside my engine when I disassembled it.
Turbo. Targa. Life. said:Man I bet those v6 2jz's are RARE!