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

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.

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.

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.

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.

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

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.

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.

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.

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.

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.

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?

Thank you, JohnnyWadd, for the correction. :thumbsup:

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

I did not know this thank you. :uhoh:

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.

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

You're right, thompson. I was going to add that in about it being bad to run straight anti-freeze. Forgot to do that. It is recommended to run at least a 50/50 mix, but most mechanics, manufacturers, and other car types recommended that you never run any higher mix than 70/30. Straight anti-freeze is actually bad for the inside of your cooling system.

Jon

Hey, would a leaky radiator cap cause the system to overheat?

Jon

If it leaked all the coolant, yes.

All right, guys... I think this car might have much bigger problems, and maybe I shouldn't have dropped $450 on her. I've owned it for two days, and already thinking I should kick myself in the ass for squandering my cash.

First off, I decided to pull the thermostat out of her to see if I could keep her cool while running down the road. And, before you ask, no I wasn't planning on leaving it that way. I know it's not good for the car to run it without a thermostat. Anyway, the first thing I noticed is that there was about 1/8 inch of gunk on the thermostat all the way around the opening. I didn't think it was motor oil, but to be sure I ran down to a local radiator shop to ask them what they thought it was. The guy told me what I thought he would. He told me that he thought it was stop-leak. Like Bar's or something similar. Evidently, this thing started leaking, and rather than fix the problem correctly, someone threw a bunch of stop-leak in the cooling system.

So, this presence of gunk leads me to believe that the inside of the radiator looks the same.

Anyway, after I took out the thermostat, I decided to take her for a drive and see if she ran hot. At first, she did okay. It ran for a couple of miles (city driving) at normal operating temperature. By that, I mean that without a thermostat, it ran at the temperature it normally runs at with a thermostat, not less, as it should have if the thermostat were the problem. I let her idle while talking to the radiator guy. It still did fine. Then, when I started coming back home, it started getting way worse. The guage pointed to the start of the red line, so I shut her down. I decided to limp her home by starting her, getting her up to the speed limit, then shutting her down, taking her out of gear, and coasting down the side streets. I made it home this way without overheating her.

So, anyway, there's no water in the oil pan, and no oil in the cooling system. However, the radiator guy told me that what these things do when the head gasket goes bad is leak between the combustion chamber and the coolant system. So, the compression increases the pressure in the cooling system, forcing coolant out (usually by creating new leaks in the cooling system). The only upside is that I can find no evidence whatsoever of cooling system leaks. Not surprising, considering that there's an eighth of an inch of stop-leak in there.

So, let me give you my logic, now. If you guys see a fault, point it out. If you have another idea, shout it out. If you agree, give me some words of encouragement. I'm thinking one of two things: bad head gasket; or so much stop-leak inside the radiator that neither the fans nor the air coming in at driving speeds can begin to cool the water. Since there is no coolant/oil exchange between the oil and cooling ports, I'm thinking that with a compression test, I'll be able to tell if the pressure is leaking back into the cooling system. Also, if I did a compression test with the radiator cap off, wouldn't I see bubbles shooting up through the water at the filler hole? Pressure will release at the point of least resistance. If I have the cap off, that will definitely be the point of least resistance.

If I find no head gasket woes, I would think that I can assume that the stop-leak is the culprit. Is there anything that I can run through there to get rid of all that shit? I don't think that just flushing it will drive that stuff out. If not, I'll just replace the radiator and see if that helps it run cooler. No, not with a new one. I'm not going to take that big of a chance.

One more thing of note. When under load, there's a bit of a rattle coming out from under the hood. Can't tell where it's coming from. It doesn't do it when I rev the engine. Only when under load. Not sure what it is. It's not really a knock. Not loud enough. Like I said, it's a bit of a rattle. You know, it almost sounds similar to the rattle a diesel engine makes when operating normally, though not near as loud. What do you guys make of that?

Thanks again for your help, fellas. I appreciate anything you can give me.
Jon

P.S. I hate all forms of stop-leak. They're evil. They should be eliminated to force people to actually fix problems that arise rather than just putting a band-aid on something that needs a tourniquet. I think that they were invented by and for people that want to mask a problem before they rip off the next owner of their car.

another thing is that if your headgasket WAS leaking pressure into the cooling system, you would see bubbles when you go to add coolant while it's running.

i think if you had it power flushed where they hook it up to a sort of hose dealy and put pressurized water through there that would knock out most of the gunk, or at least the shit that's making your car run hot.

Hey, would a leaky radiator cap cause the system to overheat?

Jon

YES, the cooling system needs pressure to function correctly. If you have a bad seal on the cap it will cause the pressure to escape.

Only use the amount of antifreeze that your demographic region dictates. Basic chemistry tells us that pure water is the best coolant, period. The specific heat of water is 1.0. This is the common chemistry yardstick that says that it takes 1 BTU to raise 1 pound of water 1° F and is assigned the 1.0 specific heat number. A 50/50 mix of ethylene glycol (the green stuff) has a tested specific heat number of 0.5 and of propylene glycol of 0.3. What this means is that it take twice the amount, in the case of the green stuff (and over three times for the red stuff) of BTUs to raise the same amount of water 1 degree!! This means that pure water will remove double the amount of heat and carry that heat away from the source per unit volume. Now, do the arithmetic and you will find out that the more pure water...the more heat gets taken away! Do not confuse this with the boiling point of the coolant. Pure water will boil at a lower temperature than that of a mix of water and antifreeze, as well as freeze at a higher point. The application of pressure in the system by the system through the normal expansion of water and gas during heating, is the solution to keeping the water from boiling away. A 10 LB pressure on water raises is vapor point to 239° F

Only use the amount of antifreeze that your demographic region dictates. Basic chemistry tells us that pure water is the best coolant, period. The specific heat of water is 1.0. This is the common chemistry yardstick that says that it takes 1 BTU to raise 1 pound of water 1° F and is assigned the 1.0 specific heat number. A 50/50 mix of ethylene glycol (the green stuff) has a tested specific heat number of 0.5 and of propylene glycol of 0.3. What this means is that it take twice the amount, in the case of the green stuff (and over three times for the red stuff) of BTUs to raise the same amount of water 1 degree!! This means that pure water will remove double the amount of heat and carry that heat away from the source per unit volume. Now, do the arithmetic and you will find out that the more pure water...the more heat gets taken away! Do not confuse this with the boiling point of the coolant. Pure water will boil at a lower temperature than that of a mix of water and antifreeze, as well as freeze at a higher point. The application of pressure in the system by the system through the normal expansion of water and gas during heating, is the solution to keeping the water from boiling away. A 10 LB pressure on water raises is vapor point to 239° F


:sly:
i always hated chemistry

That's awesome, mac!!

This overheating job is going to take a backseat for a few days. The holiday will delay me some, but I'm going to spend most of the weekend putting my stolen car back together. Once I'm done with that, I'll resume the task.

Thanks for all your input. I'll let you know what's up once I get back at this one.

Jon

A head gasket leak should show up as steam from the exhaust pipes, it will smell like coolant if there is any in the system. It will steam all the time while running not just at start up and water will drip from the tailpipe in amounts that are more than just condensation. Coolant will slowly disappear from the system.
As far as the stop-leak in the system, they used to sell a kit for flushing made by Prestone, a couple of plastic couplings and T fittings. You don't really need them to flush. Stop leak ususally clogs the heater core before it clogs the rad. Got heat?
Here's how I flush the system:
Remove the hose from the water pump to the heater core.
Add an extension piece to take the coolant away from the engine area.
Grab a 5 gallon bucket to "catch" (wink) the coolant. If it's all water then maybe not.
Fill up system with water, no sense adding coolant.
Leave cap OFF.
Run engine and catch coolant in the bucket while adding water to the system (use a garden hose).
Keep flushing while running until the water is clear.
Turn engine off.
Reattach heater hose.
Fill with water.
Start engine. Heater setting on HOT.
Open rad draincock. DON'T BREAK IT!
Keep adding water with hose as needed.
Run until clear water comes out the draincock.
Turn engine off.
Let water drain.
Here I would add 50/50 mix of coolant but in your case I would replace t-stat with new, fill with water and test drive. Watch temp and check for leaks. If all check out okay the drain 1 gallon water from system and replace it with 1 gallon straight coolant (not 50/50 mix). I think the coolant system capacity is 7-8 qts (2gals +/-) so 1 gallon straight coolant and 1 gallon water is close enough to 50/50.
They do make radiator flush to clean the system. You add it to the rad, run the car for 10 minutes and flush it out. It is caustic, I've not used it on plastic radiators. Check with parts store and read the can. This stuff is supposed to clean out rust, corrosion, and other crap from the system.
Are we sure the water pump is pumping? Can you see the water flowing at the fill cap when engine running?

i think its is the thermostat too. its probably bad and wont let the coolant flow.since no coolant going in there is none coming out obviously.the sensor to kick the fans on is on the radiator by the coolant return line.since no coolant is coming out its is reading cold all the time so it wont turn the fans on

All right, I know it's been a while, but I was finally able to play around with this thing again. I took it to my buddy's mechanic shop, and it didn't take long for us to determine that the head gasket is shot. Problem is, I'm moving back to San Diego next week to return to grad school, so there's no way that I'll be able to work on it. So, I think I'm just going to get rid of it and try and get my $450 back.

How would you guys recommend that I go about this? Is eBay a good idea for a car that doesn't run (at least not correctly)? Or should I stick with the local papers? The car itself is located in Lincoln, Nebraska. If you know anyone close who's interested in the car, let me know. It's a 1992 Talon Non-Turbo 2.0 Liter. The car is quite decent. Pretty nice shape and not all that high of mileage. If someone has the time to put a little TLC into it, it'll probably work out nicely for them. I don't have the time and I already have a DSM that I'm in love with, so this car is expendable to me. If you know anyone who wants it, let me know. Have them drop me a line at jhieb1@hotmail.com or call me at (402) 770-1118.

Thanks
Jon