alexands

My engine has about 1500 miles since rebuild and my temp gauge is usually somewhere in the middle but fluctuates wildly at times. At a red light sometimes the needle will almost hit the red zone, but once I take off, it drop dramatically (like down to 1/3). Last week it went intot the red for about a minute (before I could pull over) and spewed coolant.

Everything on this engine is new (thermostat, water pump, etc..). Any ideas what this is all about?

Thanks

hosrom_951

Double check that there is no air in the system, took me 20 mins or so to completely remove the air when the needle was stuck at almost the red mark for 1 min.

After that, i replaced both DME temp sensor and gauge temp sensors and the problem went away, but i doubt that is the problem.

shaheed

yeah bleed your system and make sure there is no air, it can be a pain to get all of the air bubbles out.

hosrom_951

Note: The best time i found to open the bleed screw is when the fans came on (speed two), when i opened the bleed screw, i noticed NO coolent comming out at all. The fans shut off, and after a few moments coolent started (very slowly) to come out, that is when i pressed on the throttle to allow the coolent to rush out of the bleed screw and tighten it.

Don't know if anyone else here noticed/has this kind of technic, also make sure that your heater is set on full blast (gets air out of the heater/coolent system as well).

alexands

What about jacking the front of the car up to do this? That's what Clarks recommends. Can I do it on level ground?

hosrom_951

Alex: Yes, level ground if fine. Raising the front just makes the air come out easier, the technic i described above was done on a leveled surface. But i waited untill trhe fans came on to start bleeding (actually waited for the fans to come on 3 times to remove as much air as possible).

You could also have a friend/college blow into the reservoir to 'force' the air out as you open the bleed screw.

Hussam

CurlyDE

I have found that filling the reservoir up and then using a rag (to seal around the air hose) and an air compressor to slightly pressurize the system works well. This was recommended by another Rennlister and has worked for me everytime.

Duke

Don't forget to turn the heater all the way to the max to fully bleed the whole system.

Charlotte944

I just went through a similar issue with my '86 and it turned out that the radiator temp switch was bad.

Make sure your fans are running when they are supposed to!

Mike S

To add to the fun....I had a similar problem and it turned out to be bad grounds. After fixing the grounds my temp and battery voltage gauges were far more accurate.

cas951

Sounds like your fan is not working. probably the switch. Another way to check is turn the AC on when the temp is above normal. Turning the ac on also turns on the fan.

Charlotte944

One thing to keep in mind is that the in-dash temp gage is woefully inaccurate, but it is repeatable.

What this means is what is a "Normal" indication for one car may be "Abnormal" for another.

What I do is make sure that all of the components are functioning properly (fans, t-stat, water pump, proper coolant level, and so forth) and then I drive the car under various conditions (stop-and-go, highway crusing, "spirited" driving, etc.) and note how the gage is indicating.

badass951

Check all of the cooling lines. Also, are you sure your headgasket is fine? I have had air bubbles in my system and they never came close to causing such bad spikes.