Head Gasket Help

[mike_01]

Hi all, Just after some advise on my head gasket please
I bought the car with the intention to change it as not knowing the history of the car and the fact they have the problem.
There were a few symptoms like the bubbling being the dash, using coolant which was escaping through the exhaust and high coolant pressure, number 6 was on 140 all the rest was around the 170-180, and a slight misfire. So I checked the head bolts for torque and it seems they were all around 80 ftlb apart from the 4 bolts around number 6 which was around the 60ftlbs, so with a re torque it did nothing, so stripped the head off and found the gasket not to be that bad. only thing I can see that would cause problems is the coolant parts are a bit messy and the cylinder was blowing between 5 -6 which was a surprise but would probably cause the misfire.

Cleaned the head, there is a slight bow to it which is obviously worse between 3 and 4, but from what ive been told that they do tend to have a slight bow being such a long head and being alloy that is should be fine when torqued down, I have a standard head gasket, not Toyota and arp head bolts and torque it down to 80-90 ftlb
I am after a few opinions first as what to do first from some supra owners first hand experiences
Many Thanks

 

[Raggan]

pull the block and get it machined decked with the timing cover installed on the block, make sure you tell them that when you have it machined. Only after you do this first step will you be able to properly install a headgasket on a 7mgte

 

[JDMMA70]

If using a OEM head gasket, clean the block as best you can with a razor or something of that nature. If possible check the deck with a machinist straight edge, other than that, this will be sufficient for a OEM gasket to seal on the block surface. Have that cylinder head inspected by a machinist.

 

[supraguy@aol]

Pic of the #6 cylinder area of the head, please.

 

[suprarx7nut]

The coolant jacket seals in the head gasket on cylinder 6 (rear) and 4 (exhaust side) are compromised and explains your loss of coolant and weak compression results.

The head should be machined flat. Before doing that, though, you should call around and find a machine shop with a hardness tester. If the head is softened (I don't have hardness numbers off hand) then it should not be used again. The aluminum is heat treated and once it loses its hardness it must be re-hardened (which is probably impossible to get done correctly) or replaced.

More info here: http://yotamd.com/toyota/mk3_supra/bhg.html

Unless you're planning a big build, I would not machine the block and I would not use a MHG. Factory head gasket, ARP hardware, ARPs torque value.

 

[mike_01]

Pictures of the head and bloke so too so long taking ages to upload for some reason.
Ah right that would explain that.
I did start cleaning the head
Thanks for the help so far.

 

[Nick M]

I think you should use the Fel-Pro headgasket which has a steel core with a composite face specifically for sealing under bad conditions. But don't just throw it in. Have it machined as already stated.