Quick question prior to ordering parts
 

I mentioned before, I bought a 90 Supra with a 7mGTE that is supposedly with a BHG. Now... I look at the car.. look at the former owners handy work (abysmal) and question the diagnosis.

So.. I put an upper rad hose on the car, filled it with fluid and then took it for a drive around the block. The oil is dirty, but I dont see any antifreeze in it. No white smoke coming from the tail pipe. I spun up the turbo.. it works adequately.

Then, I park it (this is just a one block cruise). The heat came above the bottom "C" so it was warm, but the car is pissing antifreeze out of the reservoir.

So... I take the rad cap off of my 88 and put it on the 90 (after it cooled and I refilled the rad with antifreeze). I took it for a spin again (the reservoir is filled mind you... not at the appropriate level because I didn't empty it) and no leakage. I dont see any signs of a BHG, but am still assuming it is bad. After driving it around the block (twice this time), I have fluid leaking from the reservoir (it was overfull and the cap isn't sitting on it tightly .. in fact.. I dont even think its the correct reservoir cap for this car.. lol.)

When I run the car with the cap off, I can see the fluid flowing across the top of the rad. Its gunky, so either the head gasket IS blown or the cooling system is in dire need of a flush. So.. that leads me to the question

A BHG will not make the car over heat.. or will it?

A bad water pump would leave the fluid motionless (unless there is something I am not aware of) so the pump should be functioning. The thermostat may be stuck, although that usually results in an overheat condition or a "wont heat" condition. So it shouldnt be that (the heat has never risen more than 1/8th of the way up the gauge and I have not driven for more than 2 blocks with it)

I think I have no choice but to tear off the top of the engine and assume the worst but should I flush the cooling system first? or just wait and do it after?

I have not done a headgasket on a 7MGTE yet.. so this will be a learning experience.

Also, I have an opportunity to pick up a 7MGTE (with turbo) with about 80k on it (shipped from Japan if I understand everything so far) along with a R145 Trany from a warehouse that is clearing them out. They want 690 for the engine, 275 for the tranny and will deliver it to my garage.

Good deal?

Thick radiator fluids = old, old, old style coolant WAY pats it's prime; two old types of incompatible coolant mixed and emulsified (doesn't happen if mixing incompatible modern coolants... progress eh?); oil contamination from a BHG; OR a coolant system LOADED with a HG leak stopping agent.

A bad water pump will usually move coolant... just not enough.

Yes, a BHG can cause overheating... it contaminates coolant allowing oil/water sludge to create an insulating coating on the coolant passage walls and typically allows coolant to exit the system to the point that flow is reduced beyond serviceability.

Once again
 

Burp the car. Air in the cooling system did this exact thing to mine. Do a search for Burp.

Park the car facing up a steep hill
Remove the rad cap
Top off the rad fluid
Turn the heater on high, make sure your heater valve is open force it open manually if you have to.
Rev the motor to 3000rpm several times watch it spit and complain as it forces air out of the cooling system
Let it idle with the cap off for 15 minutes while topping off the rad fluid.
Cap it and test drive it.

Preferable to do after you flush and replace with new coolant especially if you see sludge.

Drilling a 4mm hole in your thermostat where the dangle is and cutting the dangle off worked for me.

If this doesn't work repeat a couple more times after test drive.

Don't ever assume a BHG without taking it to a garage and having it tested. Always watch the test being given a tech can blow carbon dioxide into the tester by mouth to give a false positive BHG result if he wants the work bad enough, my tech at my garage showed me how easy it is to fool the public into a bogus huge BHG repair. If the tech puts the tester to his mouth cry foul.

Anytime you open the cooling system you have a great chance of trapping air in the coolant because of the high position of the Heater core relative to the Rad cap. I am doing mine a few times again after replacing the lower radiator hose.

ahh.. thats right.. this engine needs to be burped

Woot.. out to try that.

The engine really shouldn't need to be burped and the MKIII heater core flows coolant all times unless the A/C is on MAX or the heater control valve's solenoid is bad. Just overfill the reservoir, run the car just until it reaches operating temp, let it cool and then just drive like normal. The air should work it's way out pretty swiftly. If your system requires you to go to all sorts of odd extremes the coolant isn't flowing as freely as it should be.

Burp
 

What Cre says goes but with mine, I had to open the heater valve before my heater hoses even got warm past the valve. My Valve was stuck closed. I didn't have any flow back to my heater core till I opened manually the valve. Once I opened the valve a big volume of air came out. Like Cre said likely your valve is bad. It should open when using heat and close when using AC.

My car overheated till I did these things, it didn't work itself out but rather air caused coolant in the overflow to boil out. I suppose in time it might have worked out, but where would it go? Out the coolant overflow? The coolant is a sealed system except when the pressure and heat open the radiator cap valve, by then I was low on coolant escaping to the overflow bottle as boiling fluid and steam. We all know how Toyotas react to low coolant. They get real angry and pissed off when their short on coolant.

I think the system was pretty close to being bone dry though. When I bought it the top rad hose had a massive hole in it, no coolant showing, the reservoir cap was off (tube floating in the reservoir..doesnt fit correctly to the cap) and was full of gunky coolant. I added a 50/50 premix (3 litres to fill it before turning it over) after I got the top hose replacement (a Goodyear hose that I had to cut almost half off of, but it did have the correct curvature). The first time I drove it, the top hose did not feel right and fluid was coming out from the reservoir and cap. When I used my 88 rad cap on it, the cap held, but the reservoir was overflowing.

The second run around with it had the top hose with solid pressure whereas the first time I could squeeze one side to touch the other, so pretty sure the original cap was toast. It has what looks like tiny rubber chips around the top inlet (where you put the coolant into the rad itself) and the coolant is definitely not clean. With it sitting for "god knows how long" with that hole in the top hose.. no idea whats inside of the cooling system now. Not sure if I should do the flush fill or just tear off the top of the engine and see if the head gasket is actually bad (at which point, I would have to replace it anyway, along with the valve cover gaskets).

Its one of those love/hate thingies. I would love to revive it, but not sure if its worth it in the end. At the final stage, I can only truly own one Supra... and my 88 is my first love.

I should add, mind you.. the engine is very strong in this car and the turbo spooled up very nicely. I love the red now that I own it.. but the grey has its own special appeal on my 88. The AC on the 90 also works which surprised me.. blows ice cold. I am actually considering just trying to find someone who wants a project car and just reselling it.

what is so friggin annoying is that I am falling in love with TWO cars!

1990 "donor" MKIII (mmmm... donor...)
http://www.gdscentral.net/1990_Supra...s/IMG_9219.JPG

my 88 MKIII
http://www.gdscentral.net/88supra/slides/car3.jpg

Hmmmm,
 

Flush it, Burp it, swap parts off your running car to get it going and test it. Why would you pull a head gasket before you knew you had to? It's a lot of work and expense.

Previous owner said they did a leak down test (I am not really trusting that) and that the BHG was a fer shore thing. Kinda silly for him to sell it as a BHG car if he didnt have one.. so I am fairly certain it has one. Its simply the fact that the guy had no clue about anything that makes me wonder if he's quoting the old "oh yeah.. Supra? BHG!" line..

And they both run. They simply have different warts. The grey blows blue smoke at start up after sitting for longer than 24 hours. The red one wont retain coolant when driven (although its not bad enough that I wouldn't be able to drive it to a shop now). The grey 88 has a stiff 1st/second shift (probably bent forks) and the red one has a 1st gear that you have to keep the shifter held up into first to drive (not that you stay long in first and in fact I could avoid first altogether if I wanted to but it would be hard on the clutch). The grey one has had the rust removed, but I am looking at about 5k to finish it (up to final paint). The red one.. is a mystery.. lol. It has a lot of bondo on the door, etc. Just a touch of rust on the quarter on the driver side at present.

Its a 50/50 thing. Either way, I intend to sink another minimum of 10k into one of them. I originally just bought the 80 to tear off the exhaust and part out (possible use the leather interior as well). The only thing that stops me from turning it into a parts car is the fact that I am fanatical about the MKIII.. lol.

Like I said
 

Like I said, a lot of people are told BHG in the shops when they aren't or a friend that works on cars says BHG if it overheats. Best to test it yourself. How is that interior? It looks like leather. Mine is red like that to. I like the smoke gray on your car I am thinking of painting mine like that.