Low Coolant Temp
Thread Starter
Joined: Jun 2010
Posts: 174
Low Coolant Temp
2004 MC SS
157k miles
I have a P0128 for engine coolant temp below t-stat regulating temperature. So, seems like a simple t-stat change but I've noticed that the temp actually seems to increase in certain conditions. Today, on the drive home I decided to monitor the Tech2 while driving. On the interstate, for about 20 miles cruising at 65 MPH, I had an ECT of 172F with ambient air at 68F. I then got onto an off ramp to go pick up the kids, sat in idle for about four minutes, and it got up to 212F. As soon as I pulled away again it went back down.
So, I guess I thought failed t-stats were "fail open," not "fail shut." Is it possible I have a closed t-stat so my primary cooling mechanism is air moving under the car?
FWIW, the 172F isn't that surprising to me. I did LIM's two winters ago and I replaced the t-stat with whatever came in the kit. Since then my car gauge has never moved above what is effectively the 170 on our gauges.
157k miles
I have a P0128 for engine coolant temp below t-stat regulating temperature. So, seems like a simple t-stat change but I've noticed that the temp actually seems to increase in certain conditions. Today, on the drive home I decided to monitor the Tech2 while driving. On the interstate, for about 20 miles cruising at 65 MPH, I had an ECT of 172F with ambient air at 68F. I then got onto an off ramp to go pick up the kids, sat in idle for about four minutes, and it got up to 212F. As soon as I pulled away again it went back down.
So, I guess I thought failed t-stats were "fail open," not "fail shut." Is it possible I have a closed t-stat so my primary cooling mechanism is air moving under the car?
FWIW, the 172F isn't that surprising to me. I did LIM's two winters ago and I replaced the t-stat with whatever came in the kit. Since then my car gauge has never moved above what is effectively the 170 on our gauges.
Joined: Dec 2012
Posts: 107
From: Lombard, IL
farmerjg,
My 02 SS has always acted this way. While highway cruising the coolant temp gauge is at about 10 o'clock, but while stopped it will run up to operating temp. If your thermostat was stuck open, you would never see the normal temp.
My 02 SS has always acted this way. While highway cruising the coolant temp gauge is at about 10 o'clock, but while stopped it will run up to operating temp. If your thermostat was stuck open, you would never see the normal temp.
Joined: Aug 2009
Posts: 262
From: St Louis Missouri
I had that as well, replaced the thermostat with Factory GM and problem solved, looked at getting a tstat from auto parts store, but is was not the same as the GM, so went to the stealership. I also got rid of the dexcool at that time, hate that stuff, flush and put in straight water, next day flush and straight water, next day flush and straight water, next day flush and traditional green coolant, been 4 years no problems since.
