I was on my way to work and I thought I saw the battery light on for a second, and I also notice the AC wasn't as cool as it was earlier. So I shut the AC off. That's when I notice the temp gauge was higher than its been normally, but not way up near the 'H' range, so I kept going another mile or so and it got up to the 'H' range, pulled over and let it cool, it was over flowing out of the reserve tank. Took forever to nurse it home, had to call off of work. While nursing it home the temp gauge stayed right in the middle for a couple miles then all of a sudden it would go up the 'H', and I'd pull over and let it cool again. Did this about 5 or 6 times to get it home, took 3 1/2 hours. Is it the water pump or the thermostat.? I believe the battery light came on for that brief amount of time was because the coolant was blowing out of the overflow tank was causing the belt to slip along with the AC not cooling as normal along with the steering a little hard to turn for a second or 2, I hope its the thermostat, that would be way easier to change than the water pump. Any ideas ? Thanks

 

Tracker owners may not be aware hot engine coolant is continually circulated through the heater core located in the heater case inside the cabin under the dash. This circulation occurs even when the thermostat is stuck closed (which appears to be the problem here). When the thermostat is closed, coolant does not pass through the main radiator. Bypassing the radiator for a short time warms the engine block up to operating temperature quickly. Bypassing the radiator too long will cause the engine to overheat resulting in warped heads and an engine rebuild. If your engine overheats: turn off the A/C, roll down the windows, set your HVAC controls to "outside air" with the blower motor set to high. The heater core will act like secondary radiator possibly lowering the engine temperature enough for you to limp home without engine damage. Item 1 in the drawing below is the Temperature Control Door. All it does is force blower air through the heater core for warm air or around the heater core for cool air. Forcing air through the heater core will help bleed off engine heat in the event of a thermostat stuck in closed position.

 

In the process of nursing it home, when ever it got between 1/2 way and the 'H' I would pull over and let it cool. Each time the overflow/reserve tank would be full, by the time it cooled down the overflow/reserve tank would be almost empty. I know the heater core is essentially a small radiator which would help cool the engine/coolant. I did not know coolant still flow everywhere except the radiator when the thermostat is stuck closed. Im confused why the radiator would fill the reserve tank when hot if coolant was not flowing through the radiator and then suck it out. I understand it expands when hot and contracts when cool. Just like microwaving something with a plastic lid on it, if it don't blow off, when it cools it will suck it on, concave the lid. Im just confused why if fluid isn't running through the radiator why does it blow out into the overflow tank. Anyhow, you say its the thermostat, that what Im gonna do. Thanks.

 

Below is the full list of things that can cause the cooling system to overheat. The thermostat is just one of them (but the most likely). There is no test for a bad thermostat other than "inspect and replace." You could test it in a pot of boiling water but you'd have to remove it from the car first and then you might as well replace it anyway.

 

Well, it wasn't the thermostat. I was sitting the seat revving it watching the temp gauge and it stayed a little less than middle, with the A/C on. Still notice the battery light would flash once in a while. Then I smell burning rubber, so I got out and looked under the hood and the serpentine belt was barely turn, sometimes even stopping for a microsecond. So I shut the A/C off and everything seemed normal, so I took it for a short drive with the A/C off and it still overheated. Im stumped, glad I got a 08 4X4 Ranger as a backup vehicle. Any thoughts now on what the problem might be. Im gonna take the belt off and see how hard all my pulleys are. Should they all turn pretty freely.?

 

They should all turn freely. I would say it is the water pump but also check all the pulleys as they might also be ready for a change. Replace the belt!!

 

The first rule of troubleshooting is "always start at the beginning" and I am sorry I violated that rule buy jumping right to the thermostat because "it's always the thermostat." I discounted the battery light and the coolant overflow in your original description of the problem. Those were clues that are making a lot more sense now. I'm assuming you ruled out the thermostat because the problem still existed after you changed it. I'm also assuming you have the 2.0L engine since the 2.5L and the 1.6L don't have a serpentine belt. The Chevy service manual says the 2.0L has a serpentine belt and a separate fan belt. However, it looks like the serpentine belt drives the water pump. It also looks like the water pump is external on the 2.0L engine so that should be easy to change if it's locked up (the 2.5L water pump is internal and took me 3 days to replace). If none of pulleys (air-conditioner, generator, power steering or water pump) are binding, the problem could be a defective belt tensioner. If you don't have enough belt tension, the crankshaft pulley could burn the belt (causing the smell), the generator will not turn (causing the battery light), the water pump would not turn (causing the overheat and the overflow), but it should also cause problems with your A/C and power steering (trouble you did not report). Compare the battery voltage with the engine off and with it running. If it's 2 volts higher with the engine running your generator is turning. In that case I would not expect a faulty tensioner. If the generator, power steering and A/C are all working, the serpentine belt may be rubbing against a locked water pump pulley. That could also explain the burnt smell. Your plan to remove belt and check the pulleys is a good move.

 

they should spin pretty freely. isnt the ac belt a different belt on your truck? sounds pretty much like the belt is slipping causing the system to overheat but if the ac belt is separate then i really dont see it effecting both belts. do you still have heat blowing out the vents when this happens?

 

In the original description I said the steering was a little hard to turn for a second and the A/C wasn't as cool as before, sometimes. I assume it was from a wet belt from coolant overflowing out the reserve. But when I did notice those 2 things the 01 Chevy Tracker 2.0 with a serpentine belt & separate fan belt had NOT overheated yet, it was little higher on the gauge than usual but not hot by any means at the moment. I appreciate all who has been helping here. I hope to get to the bottom of this. I'll keep updating as I dig into the problem. I love Chevy Trackers and want more of them, even though I'm a Ford man, haha. Thanks again. Please keep up the suggestions and I'll keep updating as I go.

 

Also, yesterday after I finished putting in the new thermostat, when I was sitting in the car, it was hot outside so I turned on the A/C. When I smell burning rubber I got out and notice the belt sometime stopping for a second. I shut the A/C off. In the process of starting and stopping the engine I noticed the A/C center of the pulley didn't turn anymore when the A/C was engaged. I know its not suppose to turn when the A/C is off, but its suppose to turn when its on. And only the outside of the pulley spins when A/C is off but now the outside spins, the inside doesn't whether the A/C is on or not.