Can You Help Me Stop Overheating?!!

[JohnnyWadd]

Hey, guys. I'm about to embark on a project to help a friend figure out why her car is overheating. It's a 1992 Talon 2.0L Non-Turbo. She knows I'm a DSMer (though she doesn't call it that), so she enlisted my help. I took five minutes to look at it, but I didn't get very far into it, yet. I figured I'd post what I know so far and see if someone can give me a little insight as to what to look at. Maybe that'll make it a bit easier on me once I do dive in.

Anyway, the girl called me and told me that someone had told her that the water pump was out. I asked her how sure they were, and she said they were positive. So, I asked her if it was leaking any coolant from anywhere. She said "no". In my experience, a bad water pump leaks because the seal usually goes bad. Could it still be the water pump, even though it's not leaking? I've never seen a water pump just stop circulating. Hell, even when they leak, they usually still circulate, don't they? And the bearing can't be seized up. Since it's run by the timing belt, I'm sure it would've shot that bitch out of there, then I'd be in major trouble.

So, I went to the car and started her up. I only let her idle for five minutes in the driveway. I never took her out on the road. As she sat idling, sure enough, she started to get hot. As the temperature rose, though, I noticed that the cooling fan never kicked on, even though the guage approached the red line. I decided to try and jump that temp switch to see if I could kick that fan on. I know there are a couple of temp sensors on that car. The only one I messed with is the one on the thermostat housing. Is that the right one? Is that the switch that's responsible for cycling that cooling fan off and on? If not, where is it? On the radiator?

Anyway, I disconnected the plug and tried to jump across it to kick the fan on. Nothing happened. I them messed with the circuit breaker for the fan on the fuse block. Took it out, then put it back in. Still nothing. I plugged the temp switch back in and kind of played with the wires a bit, but still was getting no love from it.

Then, as I was going around to the driver's side to make sure I wasn't running it too hot, the fan kicked on all by itself. Seemed a little late to me. I felt like it should've been running much sooner. It had been running for quite a while and hovering near the red before it decided to comply. Not sure if it started because of what I'd done or not. Anyway, I watched the guage, and it dropped to a more reasonable level, but then it decided to start rising again. I decided to kill it before I got it too hot. Then we be really screwed.

So, what do you guys think? I think that there's something wrong with that fan or the switch or the relay. I don't think the pump is bad. If that water wasn't circulating, I don't think the temp would've dropped at all when the fan kicked on. That is, unless the temp sensor for the guage is near that fan, and it was reading the temperature of the coolant near where the fan was cooling it down. But, then if it wasn't circulating, the coolant in the radiator wouldn't be hot at all, right?

I'm a little confused. I'm guessing if it was strictly the fan, it would run much cooler at highway speeds, right? You know, with air passing through the radiator. Let me know what you guys think. As soon as I get a chance, I'm going to dig deeper. I'll post what I figure out.

Thanks for reading this, and I thank you in advance for any advice you might be able to give.

Jon

[ez1286]

There should be a thermal switch on the fan (well wired in line for the power but it's bolted to the fan) You can take this switch out completely and just have the fan run constantly. Are you sure the thermostat is working correctly? I'd also check for air in the cooling system.

[-Josh-]

I'm thinking it's the thermostat if it heated up that quick. You would know if the water pump was bad as you said by a noise or a leak. Try removing the thermostat and seeing if it's seized up, which will only take a few minutes of your time to check anyway. If that's not it then it could be the radiator or even the the coolant passages clogged up, has anyone ever had problems with clogged coolant passages? My number one guess it the thermostat though.

[Eclipse4ever]

Yeah it sounds like a sensor such as the thermostat went bad. usually cars that overheat have that problem. If it was the water pump it should make noises, leak or something. You also drove the car so yeah I think its not the water pump. Also ask her who told her that water pump was bad and how did they find out ? I had friends that had cars overheat, one was a Honda and a Saturn and both had thermostat problems. If its not the thermostat then check wiring and everything since its a 14 year old car and you can expect almost anything to go bad.

[Gsx_hooptie]

Because of what a pain it is, the water pump is the last thing I'd go through with. I'd follow ez's suggestion. Then, the usual radiator flush and thermostat check if that doesn't work.

Analytically it's probably the fan, but even it were most likely to be the pump, I'd do the aforementioned anyway.

[JohnnyWadd]

Okay, I thought I'd update you guys a little. I decided to just go ahead and buy this car from the girl who owned it. She only wanted $450, and I figured that even if I can't make it stop overheating, I can always part it out and get my money back. Probably more, actually. Didn't do a whole lot to her yet. I went to a couple of concerts out of town this weekend, so that absorbed most of my weekend. It was worth every minute, though. Sevendust Rocks!!!

Anyway, I went out to play with her a little bit today. Didn't get a chance to do too much, but I did tinker around a fair amount. The first thing I did was to take off both the PS and the Alt belts so that I could play with the water pump pulley to see if the bearing was bad or the shaft was messed up. It didn't feel like anything was wrong to me. Spins freely, makes no noise, and has no play. So, I'm guessing the bearing is okay. I didn't take the timing cover off to inspect the weephole, but there's no evidence of leakage anywhere below, so I'm guessing the seal is okay as well. This leads me to believe that the water pump is okay.

Next thing I did was to pull out the dipstick to see what color the oil was. It didn't appear to be a milkshake to me. In fact, it was quite black. Could use a changing. It was about a quart too full, so that's a problem. I also started her up to check for white smoke from the exhaust pipe. Didn't see any of that. So, I'm feeling that she's doesn't have a warped head or bad head gasket.

My next step was to check the coolant level. I opened the filler cap and couldn't see any coolant at all. I had an empty two liter soda bottle that I filled with water in order to fill up the system. I was going to use Anti-freeze, but I ultimately decided not to, considering that I might have to dump it all really soon if I find out the the water pump or thermostat is in fact defective. I'll definitely change that before winter hits no matter what I figure out. It took almost 2/3 of the bottle to fill it up, but that was before I drove her to get out the air pockets. Oh, and I also forgot to check the level of the overflow tank.

The next thing I did was start her up. I let her idle for quite some time (maybe 20 minutes), and the needle stayed right where it was supposed to be: pointed pretty much straight up to 12 o'clock. I didn't notice at this time whether or not the fan was cycling on and off. However, since it wasn't running anywhere near hot, I was beginning to think that maybe the only problem was that the coolant was low.

So, I decided to take her for a spin around town to see what happens then. That's when trouble started to come into paradise. I didn't take her on the highway at all. In fact, I probably didn't get much over 35 mph. She started to get hot, though. I don't think I'd driven further than a mile and the needle was starting to approach redline. When it got close, I turned onto a side street and shut her down with the intention of starting and stopping the engine to coast home. I shut her down the first time and coasted a ways. Then, I restarted her, and was able to make it all the way back home without having to kill her again. She was starting to warm up, though.

When I got back to the house, I decided to let her idle to see what she'd do. She cooled back down to normal operating temp (12 o'clock) and stayed there the whole time she was idling. I let her idle for probably another 10 minutes. I also noticed that the fan was cycling on and off as it was supposed to. After a while, I decided to take her for a spin again. Once again, it didn't take long for the needle to approach redline. This time, when I turned onto the sidestreet, instead of shutting her down, I pulled over to let her idle. Once again, she cooled down to normal operating temperature and stayed there. It took about 10 more minutes for her to cool down.

When I got back, I shut her down long enough for her to cool, then opened the radiator cap again. The coolant level was down again, but it didn't take much to fill her back up. I also decided to check the overflow tank. It was pretty close to empty, so I filled it up as well. All told, it took about 1 1/8 2-liter bottles of water to fill up the cooling system. For you non-metric types, that's just a shade over half a gallon of water.

So, what do you think? Since it cooled down to normal operating temperature every time I let her idle, I really don't think that the water pump or the thermostat are bad. I also think that the coolant switch for the fan is okay, since the fan was running. But, the fact that it would heat up when I'd start driving puzzles me. Do you guys have any idea as to what you think would cause this? Any suggestions you could give would be greatly appreciated.

Thanks for reading. I appreciate all of your guys' time.
Jon

[Turbodog97]

Well if it was nearing empty(the coolant overflow container) when you checked it again...are you sure that the radiator itself has any fluids in it at all? I would pull of the radiator cap and fill it up from there. If it's not that then it's deffinitely the thermostat.

[Black97GST]

CHECK THE OIL. Is there any coolant in it/ real watery and thin?? hopefully not. The thermostat wouldn't have anything to do with the disappearing coolant.

[gthompson97]

so let me get this straight...you put straight water in instead of a 50/50 mix? that's why it's overheating, you need to mix it with anti-freeze.

[Thor06]

Sounds like the thermostat to me. The way I understood the coolant is that water does the cooling, the antifreeze is just there to stop it from freezing right? I dont think that just water is going to have an effect on the effiecy of cooling. Correct me if I am wrong though.

[JohnnyWadd]

That's not exactly right, Thor. If you look on a bottle of Prestone (or whatever) it'll say "Anti-Freeze", but it will also say "Coolant". A 50/50 mix will protect a car to a higher temperature than straight water, and a 70/30 mix will protect it further still. Water has a much lower boiling temperature than anti-freeze, which mean that the stronger the mix, the higher the boiling temperature.

Now, putting straight water into a car will cause it to run a bit hotter, but it will not cause one to run in the red if it's nowhere close when the proper coolant/water mix is utilized. So, while I do agree that it's running a bit hotter than it should, that doesn't explain this. I'm going to change the thermostat tomorrow and probably do a radiator flush while I'm at it. Wish me luck. I'll keep you guys posted.

Thanks for the feedback.
Jon

P.S. I checked the dipstick. The oil looked pretty dark, and there was no evidence of water or coolant leaking across.

[gthompson97]

Originally Posted by JohnnyWadd

A 50/50 mix will protect a car to a higher temperature than straight water, and a 70/30 mix will protect it further still. Water has a much lower boiling temperature than anti-freeze, which mean that the stronger the mix, the higher the boiling temperature.

that's true to a certain point. i don't want someone to get the impression that if they just run antifreeze that that's the best from of protection cause it's not.

did you know that straight anti-freeze will freeze at below freezing temperatures?

[Thor06]

Thank you, JohnnyWadd, for the correction.

[ned032002]

Originally Posted by gthompson97

did you know that straight anti-freeze will freeze at below freezing temperatures?

I did not know this thank you.

When I had an overheating problem, the first thing I replaced was the thermostat because it is a really cheap fix and I figured if it wasn't bad than it was still worth replacing cause of the winter coming.

[vicv]

My suggestions:
1. Change the t-stat. Okay to run plain water for testing/diagnosis. Add it to the radiator/system directly, not the overflow tank. My gut feeling is that it was low on coolant from the get go.
2. Change drive belts. You didn't mention slippage but for a $450 car you can invest in the belts.
3. Even though no leaks seen or smelled check hoses, radiator, gaskets.
4. If all check out and the fan runs when it should put 50/50 coolant mix in radiator.
5. Temp sensor. Don't know how to check them.
Good luck