waddisme

Coolant temps have always been 180 - never varying with 160 T* and DeWitts rad. This morning, it would move from 187* to 202*, back to 197*, and just moving around, up and down from 5 - 10 degrees every 10 or so seconds. Does that sound like water pump?

c4cruiser

I had a similar thing happen with my '02 temp readings. Turned out the coolant temp sensor in the driver's side cylinder head went bad. It go so bad that it set two codes; a P0117 Engine Coolant Temp Sensor low voltage and a P0118 ECT sensor high voltage.

The sensor also affected driveability to the extend that I would get severe stumbling after about 5-6 minutes of driving starting with a cold engine. The temp ranges I saw would cover nearly 100 degrees of temp and I figured the ECM was having a hard time keeping the engine running with those variations.

Got a new sensor and it fixed the problem Install was simple as all I did was to drain about 1 gallon of coolant, put the new sensor in and re-fill coolant. Car runs great and the displayed coolant temps are rock-steady although the DIC temp now shows about 3-5 degrees higher than it had previously.

blkbrd69

Pumps generally work, leak or dont work at all.

Sounds more like an air bubble, thermostat or degraded ground.

froggy47

Did you ck the codes? Water/oil temps just don't jump around like that from a pump or stat issue, look to sensor/grd.

Hi Volts Z06

Sounds like a bad T stat.

CHJ In Virginia

IMHO you have a bad sensor or ground. Start your diagnosis there, one of them is sure to be the problem. As an earlier poster said, a pump either works or doesn't and will not cause wide variations in temp.

0JDP Tech

Does it fluctuate while driving, or sitting at idle or both? Any recent cooling system changes or leaks to cause possible air in the system?
I'd guess either the sensor going out, air in the system, or fans (if it happens only while sitting).

Feel free to call, email, or PM us anytime with questions!
- Jeremy

rfn026

Here's an article I wrote about cooling systems last year.



Richard Newton

waddisme

Fluctuations were while car was moving in 36* ambient temp. Stays at 180ish while at idle. Car has been apart for past 4 weeks for c/a bushing repl and steering rack rebuild. Will check to see if I pulled the fan connections loose. Didn't think of that.

Good article. I get spoiled by the DeWitts keeping motor cool. Even at the track, it rarely gets above 190ish, even when oil temps are at 280*.

Went for a quick spin today and no fluctuations. Maybe just been sitting too long with the front end raised.

Thanks.

Painrace

I would try this first.

Jim