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Discussion Starter #1
Ok my car is overheating. It runs normal under 70-80 MPH anything after that It starts to heat up :mad: even more in the afternoon when its really hot. I took out the thermostat thinking it was stuck. It was stuck, so I didnt put it back in. it has a recently new waterpump. It make me think its the radiator.

any one got any ideas as to what is causing this :?
 

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it could be the radiator, or with all the removing of the thermostat and stuff you created some airbubbles in the system, i don't know could be the case, another thing that maybe to blame is the fan clutch.....the last and worst thing that it could be is that your headgasket maybe going bad, are you losing coolant? i dunno just some tips....hope you find the problem
 

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Discussion Starter #3
well im not loosing coolant, and the headgasket was just replaced like 2K miles ago (when I got my Head P&P). If the car is hot the fan clutch has to be kind of stiff, right? How can I check to see if its ok? Dam I sound like a newbie :oops:
 

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thats the only way that i know to check it, yes when the car is warm it should be stiff....the only way i know it kicks on is when the car engine gets really loud, but usually it'll never kick on when your flying down the highway.....if it's stiff then it should be ok.....
 

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Ummmm if the clutch is stiff, the fan will be turning, hence you should NOT overheat, but at 4000-5000 rpm, it will be loud as all hell and you will lack power. I just replaced mine two weeks ago, locked up tight. New one, 35 bucks from autozone.
 

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Discussion Starter #6
thanks I was about to ask how much it would cost, but I guess you guyz are one step ahead all the time :wink:
 

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I remember haveing a cronic overheating problem in my old supra. Replace the pump, fan clutch and thermo. Ended up being a bad rad. Whats your coolant look like?

will
 

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I doubt its your clutch fan. To be perfectly honest, they're almost useless. If they ever do actually engage while your driving, then you've already overheated due to something else. They're pretty much just a fail safe, they should never have to come on, unless maybe you see some crazy high temps on a regular basis like some of you southerners.

Also, get a new thermostat and put it back in. If you do have a cooling problem that isn't caused by the stat, running without one will not fix it. Your car will just run really cold all the time then it will over heat just like before when pushed. Also, unless your water pump is seeping, its not likely to be that. Unless your rad is leaky or seriously clogged (unlikely), your problem is most likely a coolant leak somewhere. A very common place on these cars is the heater core valve. Its on the firewall on the PS. Check it for green depoists. Those things will often start to seep when they get really hot. Once they cool down a little they stop, which make it really hard to track the problem down to them. Also any other leaky hose can cause the problems your having. Last, the hg is a possiblity too but you should have other signs if thats the case.
 

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How long has it been since you flushed your coolant? Draining and refilling your coolant (if it has been over 2 years) will help remove sludge in your radiator and it will also be a convienent way to purge the system for air pockets as well. If your radiator is old, then you might want to drain/refill to see if you can remove any buildup even if you have drained/refilled in the last 2 years.

I drained and refilled the rad in a 92' corolla I bought last August (the coolant was dark brown :shock: ) and it definitely made the car run cooler.

"Pep Boys" around here will take old coolant off your hands. If you have a "Pep Boys" in your town I would assume that they woud also accept old coolant, but I would call first.
 

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Discussion Starter #10
Ok this is what worries me----> I had just flushed out the coolant because it was a nasty brown. Then ran some of that super flush on it to clean it out just to make sure its clean. Right now its got new coolant and it still heats up. I noticed that when driving when it heats up if I turn the heater on it cools down the temp. :mad: Heater in the summer SUCKS. The radiator was replaced with a new one by the owner who owned it before me. I heard that having the cams at a wrong position can overheat your car is this true? I will be looking for any kind of leaks
 

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I remember a while back on the Yahoo list some peeps mentioned that a bad or flaky heater control valve could cause this sort of overheating. This is the valve that is located against the firewall on the passenger's side of the engine bay, it has two heater hoses, two vacuum lines, and maybe two electrilcal connectors also going to it if I remember correctly. I took mine out and spliced the lines together with one of those plastic tube things from the prestone flush 'n fill kit. My heater and A/C still work fine, I just have coolant going through my heater core all the time, no big deal to me. My problem ended up being a BHG so I guess I could put the valve back now.
 

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Does ur rad have a fan shroud on it? My 85 tends to overheat as well, (on bar above normal) on long highway drives. I'm pretty sure its cuz of the fact I have no shroud. Everything else is good..just no shroud.
 

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props on the heater in summer comment major suckage there!!!1
mine was the same way, sounds like fan is not running, mine always heated up sittin' still at idle(fast food drivetru's not fast enough) stock fan just didn't move enough air at 800 rpm to cool it, but if you ran the heater the temp would go down. Replaced engine 2 yrs ago, and did not install ac pump or lines on reinstall so i pulled that clutch fan off last spring and ran w/a/c switch on and temp control down w/fan on low. This would activate a/c assesory fan at condensor and it actually kept eng. temps down. Last month that little a/c fan died so i installed 14" ( i think ) electric fan from mid 80's buick front driver from j-yard had to pull rad. to install and make brackets for pass side but it fit in pretty good and there is about 3/4" clearance from belts and pullies. Moves mucho air and will fog windshield when stopped in rain,(have rear hood rubber seal out, should help defrost in winter too!) but the eng. is cool and that makes me happy! :p
 

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an electric fan is a nice upgrade, but if your car can't maintain proper temps under normal usuage in normal conditions and your clutch fan still spins, then theres somethine else wrong with your cooling system and everything else you do is a band aid over the real problem. Seriously, check your heater core valve for green depoists, try bypassing it for awhile if it has them.
 

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So far, everyone has some really great advice for ya! What I'd probably try first is to make sure there are no air pockets. If you hear any gurgling noise when you turn your heater on in the car, you've got a good sized air pocket in the system. Get that front end up in the air as high as possible, and with a cold engine, take the cap off the radiator and let the car come up to temperature. That'll get rid of the air in the system.
I'd also get a thermostat back in there, a colder one is okay, as long as it isn't below 175°. If you don't want to run a thermo at all, at least cut the basket off an old one and put the "washer" back in. This will give the system necessary backpressure. Think of it like running water from a hose. If you put your finger over the opening, the water pressurizes and you get less water moving, but what is moving has more velocity. This will allow the water in the block to sit there a little longer and allow necessary heat transfer between engine and water before returning to the radiator...
As for the clutch fan, I know the one on my truck worked, because going up hills in summer, it would spin up and I'd lose most of my power, then after about a minute or two, I'd hear it release, the power would return, and the temp would be down a bit. Go to Toyota and buy a tube of the goop that's installed inside the fan's clutch. clean the old stuff out and replace it with the new stuff and it'll be just like new.
If that doesn't get it back to normal, you may be running really lean, cam adjustments could possibly cause that, but I think o2 sensor would be more of a cause.
 

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Discussion Starter #16
Flyin' Hawaiian said:
If that doesn't get it back to normal, you may be running really lean, cam adjustments could possibly cause that, but I think o2 sensor would be more of a cause.
Thats another thing that I was told when I smoged my car. that I was running abit lean. I dought its the O2 sensor cuz I just installed a new one. I noticed that there is a bit of black dust on my muffler, what is that all about? :(

I will be checking for any green deposits on my valve, replacing the thermostat, and checking the cams.

Thanks to all for the help :wink:
 

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look for leaks, any coolant dripping from anywhere. Look while the car is running, preferably while its overheating too. Just watch out for the fan and belts :wink:

And definalty don't run without the proper stat if you have to smog your car there, if its running cold it will affect emmisions.
 

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Discussion Starter #18
SupraFiend said:
look for leaks, any coolant dripping from anywhere. Look while the car is running, preferably while its overheating too. Just watch out for the fan and belts :wink:

And definalty don't run without the proper stat if you have to smog your car there, if its running cold it will affect emmisions.
Ohh the car has already passed smog. Thank God :p

there is no Oil leak or water leak anywhere under the car.
 

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Zank-My car hasnt overheated since I replaced radiator-I had same exact symptoms-Heat rise cured by turning on heater-I also had new water pump, thermo, electric fan and hoses-Thermostat housing was cracked and seeping also-BUT-It overheated until i replaced radiator-f turning on heat cures it, all my old school peeps say radiator because fan affects so little-Got an OE one from 85 in junkyard that is workin great-STAY AWAY from aftermarket-THEY SUCK-Mike P
 

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I had similar symptoms a few years ago. Car ran a bit hot on the highway over 70 MPH, just slightly above the midway point on the analog gauge. It was fine in the city. It would creep up slightly if stopped, then would go right back to center when moving.
Tested the 17 year old fan clutch and it seemed to be locked up.
Replaced fan clutch with new (cheap) Hayden unit. Problem solved.
Within 10 months, the Hayden unit locked up. Same symptoms again. Got another one under warranty (12 months). Problem solved.

Fast forward to two years later. Symptoms have returned. Hayden warranty is expired. Time for a replacement genuine Toyota fan clutch.

My 2 cents.
 
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