Overheating Problem

[Ares33]

Alright, I have an 84 Supra and whenever I take it over ~85mph for 5-10 minutes it begins to run warm, which eventually (if I don't slow down or relax the engine) leads to the car overheating. It overheated for the first time on me coming over the pass, caught me off guard and unfortunitly got deep into the red. I first was hoping it was a bad rad. cap for it was hissing, so I replaced it. Coming to school it started to get warm again, and every time sense it will. Recently:

-Thermostat last 300miles
-Coolant flush last 300miles
-Radiator cap last 150 miles
-Radiator last 40kmiles.
-No coolant in oil/no oil in coolant

Now the coolant was foamy in the overflow when I checked when running warm, but thats all I can find. Level is good, hoses are ok, no leaks.

Any ideas?

[Supra_devil]

bad headgasket? they can test for that pretty simply at a shop.

[CJSREDPRA]

Foamy coolant??? Proper mix of coolant/water????

Yep, have someone test the coolant for exhaust gasses at this point.

And you went deep into the red??? Something is definitely hurt on this motor. BHG & major warpage of the head as well???

[rumptis]

until I saw that you changed the Rad in the last 40k I would have said that because I saw alot of those same problems and it ended up being a Rad.

Was it a brand new Radiator? If not change it.

[BillyM]

Change the radiator. ...easy $100 fix. Solves it 90% of the time.

--BillyM

[Ares33]

I'll need to head home ot get to all my records to see if it is in fact a new ratiator of if it was just swapped out. Kinda a piss-poor time for something to go out, just starting college and all. Thanks for the input though, I will definitly look into the headgasket more too.

[trdmkii]

another thing to check, is the waterpump....if the coolant is not circulating correctly it can overheat.

[stevrock]

Maybe since it was all foamy there's air in the system? Wouldn't that cause it to overheat?

[batmobile]

`1

[4SFED]

Before you go spending a hundred dollars on a rad, do like Chris suggested and have the coolant checked for exhaust gasses. My bet is a BHG and/or warped head from when it overheated. BTDT, foamy coolant after a major overheat - or coolant in your oil, either can indicate BHG.

[Ares33]

Yeah, as soon as I get back in town I'm going to have it checked out. Funny thing though, I just drove from my dorm to my house and back (roughly 230 mile round trip), with speeds greatly over where they should have been for most of the trip and it didn't even get remotly close to being too warm. wtf? I don't get it. And no, the cars a manual, but that was good thinking, I would have never thought of ATF in the coolant.



Before you go spending a hundred dollars on a rad, do like Chris suggested and have the coolant checked for exhaust gasses. My bet is a BHG and/or warped head from when it overheated. BTDT, foamy coolant after a major overheat - or coolant in your oil, either can indicate BHG.

[BillyM]

overheating from BHG is completele temperature independent. BHG will push all the water out as soon as you load the engine, not slowly overheat on the highway. Gera, when was the last time you saw a waterpump that didn't pump? ...the only time I've ever seen a water pump go bad is either leaking seals, or if its REAL old it may have locked up. ...but usual rule of thumb, if its not locked up, its just fine.

The slow highway overheat is a function of a clogged radiator or RARELY air in the system or crap thermostat. First thing, pull the highest heater hose it goes to the heater control valve near the back passenger side of the motor, fill the system from there with the rad cap off. If it still does it, swap the thermostat and radiator.

.How about this, you swap out your radiator and thermostat, and if it doesn't fix it, I'll paypal you $10 to help with the cost (and I promise you my wagers dont go un-backed)...

--BillyM

[supra_toy]

I have to agree with Billy on this one.

I'm still waiting till the GB comes up....

[86SupraMKII]

Possible plugged radiator...may only get warm at certain times when conditions are right. I had a tube plugged in mine and I dropped in a new radiator...problem solved. You might wanna have the radiator checked b4 buying any new parts.

[Ares33]

Good points. Especially if the water jacket gasket in the HG is directly shot it woudl be quite evident. However if the water jacket gasket ring is just slightly cracked it might not be shoved out fast enough to generate a drastic increase in temperature. And the waterpump should start to dump coolant if it seizes through its spout...well, maybe not seeing the year. But a siezed waterpump would make horrid noise. My bet is on the clogged radiatior, for the thermostat, gasket, water outlet housing and temp sender are all new. Seeing how the problem seems to have momentairly fixed itself, I'll try flushing it a few times with somethin like Prestone super flush and see if it helps. Otherwise Ill just suck it up and buy a new one. Thanks for the help.


overheating from BHG is completele temperature independent. BHG will push all the water out as soon as you load the engine, not slowly overheat on the highway. Gera, when was the last time you saw a waterpump that didn't pump? ...the only time I've ever seen a water pump go bad is either leaking seals, or if its REAL old it may have locked up. ...but usual rule of thumb, if its not locked up, its just fine.

The slow highway overheat is a function of a clogged radiator or RARELY air in the system or crap thermostat. First thing, pull the highest heater hose it goes to the heater control valve near the back passenger side of the motor, fill the system from there with the rad cap off. If it still does it, swap the thermostat and radiator.

.How about this, you swap out your radiator and thermostat, and if it doesn't fix it, I'll paypal you $10 to help with the cost (and I promise you my wagers dont go un-backed)...

--BillyM

[BillyM]

Welcome to winter... next summer expect the same thing, but worse. ...hopefully it wont be on an important trip. I suggest taking care of it NOW. ...but hey, what the fuck do I know, I've only done the SAME EXACT THING IN TWO OTHER CARS.

...an ass? maybe. Right? ofcourse.

--BillyM

[Keyfoo]

This may sound too simple, but do you have a radcap with pressure relief lever.
make sure it down all the way or it wont hold pressure correctly and youll get foamy rad fluid. CSI brand is very easy too do this.

[StanS]

Check for cold spots on the rad to make sure it's the rad. ususally it's cold around the clog. Replacement rads are inexpensive if u have time to buy over the net. so don't wait else Billy's prediction will come true.