JAZC5

I recently purchased an older C5 and live in Phoenix .. it has an aftermarket cold air intake and I had to replace the overflow tank due to a crack ... since then she runs about 200 - 208 on the highway and is constantly bouncing back and forth between 212 - 230 in stop and go traffic and the outside temps are not even over 80 degrees .. should I be worried when it hits 115 out ??? and if so what actions should I take?

JAZC5

thank you ... Guess I know what i'll Be doing this weekend

3sACROWD

Your fluctuations may be normal for stop and go traffic. What you may be observing is your radiator fans turning on and off. Get the car up to temp then park to let it idle. Watch the temp gauge and listen for your fans to activate / deactivate. It wouldn't hurt to look for debris in the radiator along with "burping" the system as 8VETTE7 suggested.

What are your temps while driving constant speed? Do they stay fairly steady?

coupeguy2001

I live in Phoenix
You need to get to know your car.
In the summer, with the air conditioner on, one fan remains on in stop and go traffic,and the other one cycles off and on.
when you get to 35 mph, both fans stay off.
in the winter,with no air conditioner, the fans cycle on at 230 degrees,and turn off around 200
The idea that the fans can recover faster without the air on, and hotter it is, for emissions, it burns cleaner.

JAZC5

OK
As described above we bled the air from the system and it helped a little , but not the effect I was expecting ...
cruising 65 to 70 on the freeway 197 to 205 .. neighborhood driving (45mph occasional stop light or stop sign) 212 to 228 ... I jumped back onto the highway cruising 65 to 70 again never got cooler then 208
Is this normal ... do I need to go the further step and have the fans set lower ????

JAZC5

OK
We bled the air out of the system as described above .. it helped a little .. but the results were a little less than I expected ...
Highway driving cruising 65 to 70 ... 194 to 205
neighborhood driving 45mph occasional stop light/sign ... 212 to 228
sitting ... 217 to 228
jumped back on the highway 65 to 70 never got below 208
is this normal ??? do I need to get the fans adjusted ??

JAZC5

ok
Back at it again .... we flushed the system , made sure the radiator fins were clear and clean , burped the system several times (to make sure no debris) bled the air line until nothing but coolant came out ... she is still running the same as last described

(Highway driving cruising 65 to 70 ... 194 to 205
neighborhood driving 45mph occasional stop light/sign ... 212 to 228
sitting ... 217 to 228
jumped back on the highway 65 to 70 never got below 208)


what have I missed?????
p.s.
fan speeds are OEM

Drewstein

My guess would be the thermostat sticking on you when it's opening and closing.
Also make sure both fans are coming on, you may only be on one fan at idle or something.