u might want to make sure your temperature sending unit is still good or needs cleaned it located on the thermestat housing.

The needle going up and down can be a sign of a sticky thermostat, or improperly installed thermostat. The installation direction of the thermostat is often counter intuitive, it opens against the flow, but the housing does not prevent you from installing it backwards.

Gas Bubbles in your cooling system can also cause irractic temp needle behavior, this is usually bad, it does sound like you have an exhaust-to-coolant BHG, if you are losing coolant consistantly. And it will not show in your exaust, other than maybe being slightly more steamy.

The first few things I do to a newly aquired MKIII is a valve job with a new head gasket (I use metal laminated graphite, coated with teflon gaskets, usually from NAPA, and replace all the bolts with ARP, the teflon does a great job dealing with the aluminum head-to-cast iron block shearing that occurs with temp extremes, it actually reseals itself). Second thing to do, convert to all electric fans, it will keep your temp under control better, and give you a little snappier response on the throttle with out the fan drag.

I have driven both a MKII and MKIII from Oregon through the Nevada desert up Mt Rose (8000+ ft) to Lake Tahoe in July, and you will not make it up that grade without electric fans or stopping to cool off.

http://www.toyota-supra.info/forums/...64&postcount=1



All of these are very good signs too lol. Dam BHG!!!

Try to take out the old thermostat and punch out the insides of it and then replace it. Then you will know that it is not your thermostat.

Does your car use up any water? If so, and it probably does, then it could be your head gasket. I blew two head gaskets, on two different engines in the past year. You need to check your distributor!!! That is what caused both of my engines to blow. There are three different modules in the inside of the distributor that you need to check. You can test them in a few minutes, with a meter. I used my old distributor in the new engine I bought, which was a big mistake. I do not want you to make the same one. My car was smoking and burning oil. Also, when I checked the timing on my car, it was fine. But, when I advanced the engine, the timing went off the chart. This was do to two of the modules in the distributor going bad. A new distributor is only $256.00, from Toyota. Let me know if this helped you. David

Blown Head Gasket
 

My 87 Supra has a blown head gasket and ive heard about certain head gaskets that help with the tourque spec issue Toyota had back in the day. I would like to know what people would recomend for me to get for a head gasket.

I am currently in the process of determining weather or not i have the dreadded BHG. the guy that had the car before me said he put a metal head gasket on it, so i'm hoping that it's not that. I have some information though I'd like to share.

The heater core was replaced and the antifreeze that was put in was the orange kind from prestone. i have been putting that in it because it sounded like a good coolant. and the coolant was bubbling over. last night i went to buy some more at the auto parts store and the guy behind the counter almost took my hands off. WOAH he said don't put that in it. It'll gum up. it's specifically for GM vehicles!!!

i have already put two jugs of this in my car and now i'm gonna try to flush my cooling systtem with some anti gunk stuff and replace my thermostat as i suspect that it is gummed up and stuck. hopefully i can fix the problem


hope noone else has put this in their poor supra

The guy behind the parts counter was right. Dexcool is bad for any car that is not GM. They didn't even make Dexcool until 2000. So yes, go for the green stuff or get Toyotas red stuff. Definitely flush the system. Also, ask the previous owner if he got the block surfaced and lapped.

cool thanks for the advice i hate the orange stuff!!!

thermostat:replaced
coolant system:flushed

still no heat and still bubbling over

i guess its time to bite the bullet and get a head gasket

anyone have any suggestions...... i dont think i can have the block lapped
but i definately will have the head machined

Before you start breaking out the wrenches, why don't you run a block test and pressure test the cooling system? For a pressure test you only need to take the radiator cap off, and for a block test you need to take cap off and drain half the fluid in your radiator.

If you don't know what these things are just go to your local auto parts store and tell them you need a "block test kit" or a "Cooling system pressure tester".