Metro Getting Hot

[bigredmetro]

Alright, I've got a 93 metro with a 1.0 jdm in it. Temp gauge usually reads about at 5/8 mark. Last night the temp would go up the almost red then back downor a little bit, then back up, then back down. It would do this for off and on, not very consistently. The coolant is actually getting hot because the first time this happened coolant spewed out from overflow tube. At the time, I thought my 50/50 mixture had to much water it, so i added straight antifreeze to even up the mixture and that seemed to help. That was about two weeks ago. Then every couple days, it will do this erratic thing. Turning the heater on helps drop the temp, but its still too dang hot in Texas to be turning the heater on. So I'm thing it's probably not thermostat because of the inconsistency, plus I replaced it about 12k ago when I put the jdm in. Could it be coolant temp sensor. Can you test it with a voltmeter? Or faulty wiring. Fan is working also. Any suggestions are greatly appreciated. Thanks, Ross

[Johnny Mullet]

Sounds to me like there is air trapped in the system. The temp gauge on all Metro models should read right at the halfway mark at all times. Try jacking the front of the car up so the rad cap is higher than the rest of the engine and run it with the cap off to burp out any air. It may take 15-20 minutes till it's all out.

Let us know what you find.

[fubard]

JM : makes some great points to check. It's easy to leave trapped air in the cooling system. Also, don't trust a new t-stat necessarily. Sometimes the quality leaves a lot to be desired and a new one is cheap enough.That and maybe a new rad cap. Don't use 100% anti-freeze 50/50 or 60/40(H2O) in your climate. You could check the rad; it may be partially blocked with junk kicked up from the road. Make sure to check your timing. Another thing to consider is a worn out rad hose. As the hose ages it loses it's stiffness and can collapse when the water pump tries to draw large amounts of coolant through it. This causes a restriction in the cooling system which in turn lowers the cooling efficiency; again another cheap fix. Check the bottom rad hose it's quite often forgotten due to it's location.

As a final solution you could move north .Our weather is mild but you'd need a valid passport since we don't just let anyone in.

When I did the head gasket on mine I removed the rad and used CLR to clean it out. A lot of junk came out. Your car is 15 years old it may be time for a new rad.

Good Luck

[idmetro]

If all of the above checks out, take a look at the fan sensor. It controls when the fan turns on. I had one go south and the car was fine as long as I was going 35+ but if I got below that it started to heat up. Got the sensor replaced and problem solved. I believe there are two similar sensors on the car, you will know you have the right one if you jumper it out and the fan runs continously - this might also be a way to verify the sensor has gone south. If you jumper it out and drive around without having a temp issue you've likely found your problem.

Good Luck

[bigredmetro]

Good points from all of you. I managed to find the time to jack up the front and was able to burp some bubbles out (about a quart or so). The hoses are good, for some reason I cut the old ones off when I put in the JDM, so they are fairly new. I did notice that when I shined a flashlight down the radiator (it was dark), there was a lot of calcium or lime build up inside. I going to try and clean it out with CLR when I get the time. Radiator cap looks good to. So I've driven it for two days since burping it and has run normal temp so far. The issue I had would not happen everday before, though, so we'll see. A question about the fan, though. When is it supposed to come on, and how long should it stay on? I noticed that when I was burping the air out it came on after idling for about 10 min and only stayed on for about 10 sec. The temp never got about 5/8 mark when I was doing that. Thanks for help.

[idmetro]

The fan is only going to come on when the coolant sensor heats up, closes the circuit and energizes the fan.

The timing of it switching on will be dictated by the temp of the coolant passing over the sensor, which will be impacted by engine rpms, radiator condition, water pump condition, amount of air flowing through the radiator, coolant concentration, coolant level, etc... which is to say it will be tough to predict.

In my experience having the fan come on at about the 5/8 mark would be normal and running for about 10 seconds at idle would again be pretty normal. If you were travelling down the road I might expect the fan to run a bit longer but if you are going 35+ you can get enough airflow through the radiator to virtually eliminate the need for the fan (unless it is really hot outside).

Sounds like the air in your system was the culprit.