Well when doing some diagnosing this morning I wanted to check if this is normal on my 1999 2.2L (automatic).

Motor was cold, first time started for the day and I connected my ODB2 cable and watched the coolant temps and air intake temps as I am troubleshooting some issues.

Coolant temp was about 77F and Air Intake was 80F. So I idled the car and watched the coolant temps rise, and at about 165F the thermostat openeded and about 170F the fan came on and never went off even though the coolant temps did drop to around 163F. During this time the air intake temps rose from 80F to about 88F, maybe due to the fan blowing the hot air over the intake?

Is these numbers normal? Keep in mind the motor was sitting all night so it was cold and was NOT driven at all during this test, simply at idle.

Thanks,



J

sorry to go off topic but where is the thermostat located on the 2.2?

Seem's a low temp for the fan to come on at. From what I have seen using HPT GM programed the fan to come on at 223.



FU Tuning

mike, in the lower hose.

Z, the fan should turn on and off not stay on . the temps seem low to me too. air intake is ok but the thermostat isnt opening till 180f so its a waste of time the fan turning on at such a low temp. if your not seeing at least 200-210 F somethings wrong somewhere.


01 cav w/01 3400 gam gt 4t45e

This is what I was thinking. Either the thermostat is opening too early OR the coolant temp sensor is somewhat flakey. I did notice that is it evident that the coolant temp sensor has been replaced already as I see where there is butt connectors inline near the actual connector OR the pigtail connector was replaced. Could the butt connectors cause any issues thus affecting the resistance of the coolant temp sensor thus throwing off the coolant temp readings?



J

I would rather see a soldered splice cause the crimp connectors dont keep out moisture and often will corrode the copper wire causing a poor connection (higher resistance). You just cant beat the reliability of a soldered and heat shrink splice. Look for a seafoam green film on the copper wire going in the butt splice, thats a bad sign. Also I have seem moisture get in the plug of the sensor too causing green corrosion and a higher resistance. Usually if the reading is way off ,cold start fuel will be applied when its 85 degrees for example, causing a hard start or check engine light. I had a 96 chevy hd3500 that had this problem, as long as the temp outside was in sinc with the bad reading given by the sensor the truck would fire right up, hardly even crank. but if the temps were no where near the bad reading you would have to hold the pedal to the floor to get it to start, and still would be tough. I ended up changing the plug for the sensor ( green corrosion inside the "water tight" seal) fixed it instantly.


01 cav w/01 3400 gam gt 4t45e

Good stuff, I will cut out those butt-connectors and solder the joints and heat shrink them and maybe that will do the trick? If not, I will check the other things that y'all have mentioned. Thanks for the tips.



J

HELP!

Okay, I replaced the thermostat which a AC DELCO one and new gasket. Now here what I did to replace the coolant which I drained via the radiator drain plug...

I re-attached everything, hoses etc. opened the bleeder, kept filling the overflow bottle till coolant starting weeping out the bleeder. Closed bleeder, made sure overflow bottle was near full, put cap back on and took the car for a short drive (maybe 5-10kms). With car idling, then checked the overflow bottle it sounded like a monster in there, bubbling like mad, then the water pump starting squealing! Looked in the overflow bottle topped it up as some had overflowed due to bubbling. Checked the bottom rad hose after the thermostat and its cold?? I turned the car off, opened the bleeder, no coolant leaked out. Squeezed the lower rad hose and coolant then leak out from the bleeder. Could it be I have severe air in the system still? What should I do to get my car back up and running? I have parked it for the night as its too dark outside now. The temp guage is the car went about a tick past the middle but never in the red, and the coolant light never came on BUT the ETS light did flash occasionally when I did the little commute.




J

*update*

So after messing around with my airlock issue, it was indeed the cause of my thermostat not opening.

What I did to apparently eliminate all the air was jacked up the passenger side as high as I could with my hydraulic jack. Then started the car with the system pressurized (rad cap on) I revved up the motor slightly and then opened the bleeder till a steady stream of coolant came out. I did this a couple of times. Also I squeezed random rubber coolant hoses to help push out any residual air while the bleeder was closed. Went for a test drive, lower rad hose is now hot, thermostat opens just over 180F. Re-verified coolant level, looks good, will top it up tomorrow morning to the cold mark on the reservoir.


J

Some J's that I have had , seem to like it if you fil up the tank get them up to op temp, shut them off ,then let them sit for several hours , over night , then top off the coolant the following morning. If not you fing yourself milking the upper radiator hose and bleeder to get the air out, You know , open the bleeder, squeeze the hose, close the bleeder, release the hose, open the bleeder, squeeze the hose..... and so on.

Yep sounded like the thermostat not opening.


01 cav w/01 3400 gam gt 4t45e