overheating
Thread Starter
Advanced
Joined: Mar 2008
Posts: 93
Likes: 0
overheating
For the past cpl of months my 89 with 49,000 miles has been overheating. It will do fine on the highway for 100 miles. Pull into town and make a few stops it temp will start climbing and not stop.
I have done a coolant flush and have replaced thermostat. It seems that the appropriate fan is not always coming on when it should. The problem is sporadic. Anybody experienced this and what was the fix?
IndianLan
I have done a coolant flush and have replaced thermostat. It seems that the appropriate fan is not always coming on when it should. The problem is sporadic. Anybody experienced this and what was the fix?
IndianLan
Last edited by IndianLan; Apr 15, 2009 at 01:40 AM. Reason: spelling
Pro
Joined: Sep 2003
Posts: 655
Likes: 2
From: Rio Vista ca.
What temperatures are you getting when the car is "over heating"? These cars are designed to run hot. In stop and go traffic my '89 will easily get up to the 220s. I don't think the fan even comes on until 226 or 227 degrees. If it gets much hotter than this you might have a bunch of crap stuck to your radiator. I don't think you can even see road debris on the radiator without removing the shroud.
Melting Slicks
Joined: Dec 2004
Posts: 3,285
Likes: 52
From: Jacksonville, FL
St. Jude Donor '08 thru '26
Our cars are vacuum cleaners. They suck up everything right to the front of the A/C and radiators.The fans have programmed "turn on" and "turn off" temps. A quick check to see if the relays & fan motors are working is to hit the A/C button and go look that both fans are running. You could also just let it idle and watch to see if both fans come on progressively I think the left comes on first, and then the right if the temps get high enough and then the right one shuts off once the temp gets below a set point. Ofcourse that is without the A/C on. If you have a scanner hooked up you will see the temps that both come on and off at without the A/C compressor engaged.
go over to our site, here's the link, and look around at our "cooling system" disscussions. They will apply to any C4, not just our cars.
http://www.zr1netregistry.com/ZR1_howto.htm
Last edited by tomtom72; Apr 15, 2009 at 09:57 AM. Reason: link added
Thread Starter
Advanced
Joined: Mar 2008
Posts: 93
Likes: 0
Hmmm, mine has been typically running in the 210 range in town, not getting over 212 before fan would come on. When it does it, it will start climbing and would go up to 230 or more, which it has not done in the past year I have owned the car.
IndianLan
IndianLan
Pro
Joined: Sep 2003
Posts: 655
Likes: 2
From: Rio Vista ca.
Yea, I'd start to worry if my temps got above 230. There are threads in Search for ways to check the front of the radiator for debris. I think you have to be careful removing any debris so you don't damage the fins on the radiator. I don't know if a faulty thermostat would cause your over heating or not. I think that there's a lengthy dispute here about the advisability of installing a 160 degree thermostat. You might want to search "thermostats" too if you've got a lot of time to read the opinions of those on both sides of the thermostat isle.
Good luck, Kim
Good luck, Kim
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
'89 spec is 226 for the Main (ECM driven) and 228 for the Aux (controlled by a head switch and rarely if ever should come on). With a/c operation, the ECM grounds the Main Relay with head pressures of 220 psi and it'll see that a couple of seconds after start up on a 70 degree or better day regardless of Coolant Temp. You troubleshoot with a scanner (so that you can see the Coolant Temp Signal). You can also ground the Diagnostic Link which should turn on the fan. To look at the a/c side, you need a Manifold Gage Set. Since it's intermittent, I'd guess your Fan is working as it should be and that it's more probably a flow issue - either not enough air through the radiator or given your mileage & year, it's all plugged up because your head gasket has been leaking for the last 10,000 miles or so and 50,000 miles is about when that shows up. Start with the scan - look inside the radiator for crud - pull the #7 plug and see how it looks.
