coolant question
 

ok here is my problem. last week i replaced my thermostat with a 180 and drilled 2 small holes in it. extra coolant flow. now it runs around 1/4 temp on the gauage :) but no i have noticed that it is pushing coolant into the over flow. :( causing my car to get low on coolant and run hot :( i have to add about 1/2 gallon before i go to work and 1/2 before i come home :( and i only drive 39 miles one way. i was thinking it was a bad radiator cap but someone said it was a bad head gasket. what do you all think? anybody else ever have this problem? there is no smoke out the exhaust or in the oil either. it also does not run rough or anything else like that. thanks

It does sound like the headgasket. I had the same problem and so have many others here. The leak appears between the cylinder and the coolant mostly in the rear of the block. You could try retorqueing the head bolts but the damage has probably already been done.

You may be able to get away with a radiator sealer, but probably not. If you do pull the head, post some pictures of the head, combustion side so we can see how bad the water passages are. Sometimes they get so eaten up that the head has to be replaced, but milling the head and new gaskets along with new head bolts or ARP head bolts and torqueing them down to ARP specs cures the problem for many many years.

Sorry to hear of your problem, but as you will find out, that is by far the number 1 problem with the MK111 Supra. Let us know.

Russ

Yeah, it could be the head gasket, but also by drilling those holes in the thermostat, the system cant build up enough pressure. I would just try putting in a 180 and not drilling holes in it. Thats were i would start.

oh its building up pressure. so much that it blows so much coolant into my over flow that it over flows causing my coolant to go low and even after the car sits for 8+ hours the system still has pressure in it. shoots air and coolant out when i take the cap off

yep...sounds like a blown head gasket...!!