cooling system issue
 

hey everyone
02 camaro 3.8. recently the coolant temperature gauge has been going in and out on me and recently just doesnt even move anymore from the resting position even after driving for a bit. i figured the coolant temperature sensor was going bad. i replaced the sensor today and that wasnt the issue. so i went further and replaced the thermostat and that also wasnt the issue, the guage still didnt move.

the ses light is on and im pulling the code p0128 which says coolant temp below thermostat regulating temperature, also the fans are on non stop. after i changed the thermostat i filled the radiator up with coolant, let it idle for a bit, and nothing happened...top radiator hose is soft also. i figured the thermostat would open and begin to let coolant flow. id appreciate any help from you guys, just want to get this fixed because i dont want to drive it im not sure what kind of damage it could do to the motor if coolant isnt flowing. thanks.

jon

Did you check the coolant level before you took it apart to swap the t-stat just to make sure it wasn't leaking anywhere? Have you made sure you got all of the air out of the system since you installed the new t-stat?

- Justin

Do the 3.8's have 2 ECT sensors like the LT1's? I was going to say hook up a scanner up to it and see what temp the Computer is reading.

the coolant level before i took it apart to swap the thermostat was low actually, the radiator wasnt full of coolant like i usually keep it. but after driving / during driving ive never smelled burning coolant or saw fluids underneath the car.

i dont even think the coolant was flowing...i shut the motor down after a couple minutes since i dont know how hot it was getting in there since the guage was still not reading right. could it be that the guage wasnt even getting a reading since there is no coolant in the motor since the thermostat didnt open..i just dont want to crack a head.

When you changed the ECT sensor, did coolant pour out? I would think if coolant poured out, it would heat up the sensor and give a reading

Yes, that's my thinking....no coolant touching the sensor. Time to start looking for the source of coolant loss.

Have you checked around the waterpump see if there are any signs of coolant near the weephole?

- Justin

yes when i changed the coolant sensor coolant did pour out

i havnt seen any coolant anywhere..ive had that issue before with my water pump and when it was leaking from the weep hole it was spewing coolant everywhere. ill uninstall and reinstall the sensor and see if that helps any also if coolant pours out then too.

im curious to see if i put the sensor in a pot of boiling water near the car if it sets the gauge off...im also thinking maybe the gauge cluster is faulty

I wonder if something is wrong with the wiring. It looks like they use one sensor for the gauge and the computer. I would be interested in what the computer is reading but judging by the code and fans running, I'd say it isn't reading correctly as well. Make sure you top the coolant all the way out and work all the air out. I usually run the heat on high and wait for it to get hot. Give it light throttle, like 2k, letting off and getting back on every few seconds, and wait till you have good heat.

yeah adam i thought the same thing. i went outside to mess around with it some more and see if the coolant level was low or if it was leaking coolant somewhere. no coolant in the engine bay or under the car. took it for a spin around the block, gauge still at 0, fans still on...so i keep it idling there and im doing something to my jeep parked right next to the camaro while its idling...and next thing i hear is a click and the fans go off...walk over and check the gauge and its at 210. ses light still on i took the scanner and erased it. so it works great now i guess i made a dumb mistake yesterday and didnt let it warm up enough. just hope when i did drive it with no coolant flow that there is no damage to the motor. thanks for the help guys.

Jon

Sounds like it was just a good air pocket. Make sure the fans cycle on and off with it idling and the coolant level is topped up.