Can You Help Me Stop Overheating?!! Options

[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