car running too hot

[94fordmustanggt]

I've got a question for ya. My car is a 94 GT with the stock 302. For some reason now when cruising down the highway on a hot day around 60 or so with the AC on the engine temp keeps increasing. I have an autometer water temp gauge so it should be accurate. It also does this when cruising down the interstate on a hot day without the air conditioner. At around 70 and up the temp keeps increasing until I slow down. It's fine at night to go as fast as you want it never goes above 180. In traffic I'll turn the AC on till the car gets up to 200 or 210 and then turn it off and let the temp drop back down to 180. What I have done: new 180 thermostat, new stock replacement radiator, changed the coolant at about 60%water, 40% antifreeze, cleaned the AC condenser, put the front air deflector on it since it wasn't there when I bought it, and backed the timing off a little to 12 BTDC. The electric fan is working; but I don't know if it's a 2 speed fan and if it is if the high speed is working if it is. It kicks on at about 160. Nothing has helped. During the winter when it's cool out it will run about 175 at 60mph and cooler if I go faster. The only thing left I can think of would be the water pump; but I don't know why the water pump would cause that. The car has about 190,000 miles on it and 3.27 gears, so it's not turning a lot of RPM. It had been screwed with by the previous owner who was obviously an idiot. Any suggestions would be greatly appreciated, cuz it's hot in Florida! Thanks

 

[sick_azz_cobra]

i had the same problem i think its this hotass weather, went to a 2 core fluidyne, no more problems.

 

[94fordmustanggt]

Maybe. I would think that Ford would have taken that in to consideration when they used only a little 1 row radiator to begin with! I thought the old radiator was probably clogged up inside so I just got another one cuz it was only $80; cheaper than a water pump!

 

[SeventyMach1]

One CHEAP thing to do that may or may not fix it .....

Replace the radiator cap. Especially if you still have the original on the car.

 

[STM1965]

Its your rad, replace it or get it flushed cause its most likely plugged.

 

[fish254]

what would replacing the cap do??

 

[mo_dingo]

If you are only seeing 200-210, then that is normal and leave it be.
Scott

 

[SeventyMach1]

what would replacing the cap do??

Keep pressure. The more the pressure, the higher the boiling point. I believe there's a long thread on corral that I saw about it. CLICK HERE TO SEE IT

The good thing is that it is NOT one of those band-aid fixes. It's something that's supposed to be there and in tip top shape.

 

[HISSIN50]

Keep pressure. The more the pressure, the higher the boiling point. I believe there's a long thread on corral that I saw about it. CLICK HERE TO SEE IT

The good thing is that it is NOT one of those band-aid fixes. It's something that's supposed to be there and in tip top shape.

No, not that thread! (I'm kidding - it started out ok). I'm so sick of getting notifications on that one.

Justin is right - the cap is important (I wont post specs again).

How does your fan kick on at 160*F? If that's accurate, there's an issue afoot.

Was it a decent quality t-stat? Some of the cheapies dont open consistantly and can be damaged by air in the system.

It could simply be that the stock replacement radiator cant reject enough heat. While driving, temps go up. At idle, there's less stress on the motor and the cooling fan works well, so temps come down a little.

You can use an IR thermometer to note inlet vs outlet temps in the rad. If the delta is decent, that might be as good as you can do.

The stock cooling system set-up sucks for folks in hot climates.



Random thoughts. Good luck.

 

[94fordmustanggt]

Ok I did forget to mention that I did put a new cap on the radiator when I put the new radiator in it. The radiator is less than a year old. The radiator cap is rated for whatever pressure the book called for. It's a Stant I think; I know the thermostat is a stant heavy duty. I don't know why the fan comes on at 160; but it always has. Even when starting the engine cold and just letting it idle when it hits 160 the fan kicks on. The thing takes forever to warm up. The previous owner(s) all screwed with the car so I don't even really know what all has been done to it as far as that goes. The hottest I've ever let it get is a little over 220. I wanted to see if it would level off but it never did. Just kept increasing slowly. As soon as the AC is turned off or you slow down it drops right back down to 180. I did check the flow and temp with one of those little handheld laser thingies that tell ya the temp when you shine it on it. Everything checks out properly. It's drivin me nuts-

 

[STM1965]

Have you checked the circuit breaker at the fan connection? I changed mine while seaching out one of the many reasons mine was over heating a few weeks back. It was starting to go (contacts melting through) It helped by bringing the fan on consistantly every time. Since you've got a new rad & cap that should rule them out. Did you install the rad yourself? If so are you sure you got all the air out?

 

[94fordmustanggt]

Yes I'm sure that I got all of the air out when I changed the radiator. I burped it and checked it afterwards. Doesn't leak or use any coolant at all. As far as the fan goes I'm not sure. I know it comes on at 160 anytime I can see it; I don't know if it comes on when going down the road or if it's supposed to. I've always been told that you don't need a fan if you're going over 35 mph; which is what stumped me about the high speed overheating also. It just seems like the radiator isn't enough to do the job; but if it wasn't adequate why would Ford have used them in the first place?

 

[gcomfx.com]

I see the same thing here.... except I have the stock guage - so that might be an issue with mine.

I've put a stock replacement radiator in, new coolant, new 180* t-stat, new radiator cap, new temp. sending units. Plus I put a High Flow water pump on the car. For some reason it runs hotter on the guage this year, than it ever has. Very strange.

I did change my air filter placement. I'm thinking maybe it's sucking in hot air which is making things worse? Going to move it to the fender soon. (broke my pinky toe, so haven't been too gunho on working in the garage.)

Subscribing, maybe we can get both our cars fixed.

BTW - I really recommend the manual bypass on the fan. All you do is run a ground wire (from a switch) to the fan to make it kick on high, so it's really easy to do.

 

[WhiteDevil]

your fan shouldnt come on until around 205 degrees or so. Unless you hve your A/F on. Or you have yoru computer tuned.

 

[SeventyMach1]

208* is what I seem to remember ......

 

[HISSIN50]

Yes I'm sure that I got all of the air out when I changed the radiator. I burped it and checked it afterwards. Doesn't leak or use any coolant at all. As far as the fan goes I'm not sure. I know it comes on at 160 anytime I can see it; I don't know if it comes on when going down the road or if it's supposed to. I've always been told that you don't need a fan if you're going over 35 mph; which is what stumped me about the high speed overheating also. It just seems like the radiator isn't enough to do the job; but if it wasn't adequate why would Ford have used them in the first place?

I'd want to check the ECT calibration.

If I hadnt installed the stat myself, I'd want to install a good one (Mr Gasket, RS, et al). You noted prolonged periods to warm up and running hot - that aint normal.

The fan shuts off in the mid 40 mph range. You need to confirm that it's doing what it's supposed to be doing, at all times.

When parts are all new, they're efficient. These cars are over 10 years old and each part losing some efficiency (let alone mods) all add up. I personally think the stock radiator and fan temp thresholds suck.

Random thoughts. Good luck.

 

[94fordmustanggt]

Is the fan supposed to come on going over 40 mph if the a/c is on? With the a/c off the car doesn't get too hot unless you're cruising at 70 or higher when it's hot out for a while. If the a/c is on it just keeps getting hotter and hotter. I did put the thermostat in myself; but I bought another one and when I have time I'll check the one that's in there or just replace it with the other one I have. I also put water wetter in there when I changed the radiator which didn't help any. If the fan is supposed to kick on high whenever the a/c is on then maybe it is just running constantly on low. Is there an article on here of how to check which speed the fan is running on?