Dammit...

Driving today and my car started to overheat. I panicked because it has NEVER moved past a certain spot on my temp gauge. So it started slowly climbing and I about shit my pants. It would be fine if it weren't like 50 degrees today for the first time since the rebuild. Later, I was doing 55 on the highway and it started doing it again. I turned the heater all the way up and babied that thing like none other the whole way home. One thing that I thought was odd: driving back on the highway I hit a stoplight and the temp went down. I wasn't expecting that, but it kinda ruled out the whole heeadgasket thing imo.

tl:dr My car is overheating a little and I doubt it's the whole HG problem.

Is it possible that it could have something to do with the alternator/battery? This problem only arose after I jumped a friends car a few times while we were fixing it. Also, I know my alternator bearing is going out and I'm running a 200w subwoofer off of the battery.

Another thing: How do I test my cooling fans? Every time I stop the car to check, they're not on. I tried letting the engine run for a while to see if they came on, but nothing, I also tried driving a while, pulling over, and immediately turning the engine off (to accessory) which has worked before.

if you're running any reasonably draining audio why aren't you running a cap, they're cheap and well worth it.

No air pockets in coolant? No recent coolant change?

If there are no other indications of a blown headgasket - like dropping coolant level - and you are sure you are free from air pockets then I would start to suspect the thermostat. If you get heating problems on the highway then it's usually not the fans since the airflow from driving should be sufficient.

If it started to overheat in city traffic then I would suspect the fans.

if you're running any reasonably draining audio why aren't you running a cap, they're cheap and well worth it.

 

No air pockets in coolant? No recent coolant change?

Assuming you're talking about a capacitor, there's no need with a 200w max system. There are no air pockets in the coolant and I hacen't changed the coolant for a good 1k miles.

If there are no other indications of a blown headgasket - like dropping coolant level - and you are sure you are free from air pockets then I would start to suspect the thermostat. If you get heating problems on the highway then it's usually not the fans since the airflow from driving should be sufficient.

 

If it started to overheat in city traffic then I would suspect the fans.

Coolant stays put and there's no foamy shit in my oil. It doesn't overheat that much - only 1 or 2 tick marks - so I suspected it to be the fans. It did overheat in city traffic when I was stopped. Thats when I FIRST noticed it. Do you know how to test the fans?

1. check your cap

2. check your level

3. check for leaks

4. check to see if you have clogged radiator

5. check your water pump and thermostat

GL!

Coolant stays put and there's no foamy shit in my oil. It doesn't overheat that much - only 1 or 2 tick marks - so I suspected it to be the fans. It did overheat in city traffic when I was stopped. Thats when I FIRST noticed it. Do you know how to test the fans?

Step one is to make sure that the car is cold and ignition off (to avoid chopped finger accidents) and try to rotate them manually, they should be easy to move with your fingers.

The fan engines are 12V so you can find the electrical connectors and feed them directly from the battery. Then you can at least figure out if the fans themselves are OK. Looking at the wiring diagram the black wire is ground, and if there are two other wires they should be for full and half speed.

Next step would be to rig a lamp for each fan to see if they get power when the engine gets warm. Just start the engine and see when the temperature rises. If it starts to get "high" and no power to the fans you have a problem with the electrical feed.

Activating the AC shall also start the fans, so that can save you some time.

Both fans has a 20A fuse each, and one shall be #13 while the other shall be in the AC relay holder.

The fan relays are controlled from the ECU by the Green/Red (normal fan control) and the Red/Blue (AC) wires. When the fans are off the voltage shall be +12V on both, and when they are on any of them shall be close to 0V.

The fans shall be controlled by the engine coolant sensor for the ECU, and it looks like it's not the same sensor as for the gauge, so if you have problems with the coolant sensor for the ECU then your problems may be caused by that.

If the fans works as they should then my guess would be that your thermostat isn't working as it should. And it's located under the engine where one of the radiator hoses meets the engine. It's held in place with two screws and should be fairly easy to change. Just note the orientation of the old thermostat before changing. The sensor body shall be towards the engine. And a new thermostat is cheap enough to waste money on without too much thought. Don't forget to have a fresh gasket and fresh radiator fluid to fill up with. Notice that in general concentrated fluid is cheaper than pre-mixed since you will pay for water with pre-mixed. However if your tap water is high on minerals you should go for the pre-mixed.

I hope that this at least has given you some clues.

Disclaimer - I got the electrical info from the Haynes wiring diagram, so it may not be entirely accurate. But you should have some info printed in your fuse box too which should be more accurate.

1. check your cap

2. check your level

3. check for leaks

4. check to see if you have clogged radiator

5. check your water pump and thermostat

 

GL!

Rad cap is fine, coolant level is fine, don't know about leaks, but it's not dripping fluid at all. Water pump and thermo are both brand new, but the thermo could still have failed. I'm decently sure the radiator isn't clogged. How do I check for that? Also, are there any tests I can do to figure out more about it?

Alright I called my local Subie dealer and priced a few things. I asked about a Thermostat, he told me with the gasket it would be ~$25. Not bad for an OEM part. I asked about an Alternator (since I need a new one anyway) and he said that it's like $125 - a $50 core charge for the other one, so totaling $75. I asked about a radiator and he suggested to go aftermarket, and that it would probably be on either side of $100.

Got a couple questions for everyone: Would it be worth replacing all of this stuff for $200 or should I find the problem and replace that part? Do you think I've narrowed it down to the most likely possibilities? Thanks guys.

Gremlins. If you don't know what it is, it's probably gremlins.

RAAAAAR!!

http://www.motorstown.com/images/amc-gremlin-03.jpg

Alright I called my local Subie dealer and priced a few things. I asked about a Thermostat, he told me with the gasket it would be ~$25. Not bad for an OEM part. I asked about an Alternator (since I need a new one anyway) and he said that it's like $125 - a $50 core charge for the other one, so totaling $75. I asked about a radiator and he suggested to go aftermarket, and that it would probably be on either side of $100.

 

Got a couple questions for everyone: Would it be worth replacing all of this stuff for $200 or should I find the problem and replace that part? Do you think I've narrowed it down to the most likely possibilities? Thanks guys.

It's best to narrow it down otherwise you will put a lot of work and money into the wrong things.

And a thermostat can be bad even if it's new.