I live in FL so its freaking hot here and use A/C all the time. car has always run around the 208 temp. Did oil/filter change and swapped out f45 front shocks for c6 Z06 shocks and installed resistors. Now car seems to be getting hot at low speed. was up to 240 in traffic soon as i get moving at at normal speed (the faster the better) it cools down to around 210-215ish.

Started car up in the garage today let it heat up with the A/C on both fans appear to be running heard the fans go into high speed mode a couple times. The Temp held steady at 198

I Raised RPM to 3000 for 30 sec intervals and watched the temp continue to rise as it did I did not notice the sound of the fans kicking into high speed mode anymore and the coolant temp got as high as 250 (sitting in the garage) before I shut it down.

So whatcha y'all think about this sudden issue that has popped up? replace the fan relays and see what happens? I know it has to be coincidence but seems awful odd that I've never had an issue and now out of nowhere it starts running hot after the oil and shock changes.

BTW coolant is full and looks good didn't see anything wrong or blocking radiator. Also did air purge procedure (just in case) since I had to move the overflow bottle around while doing the shock replacement but as expected made no difference and coolant remained full.

 

Sudden issue: first step is verify temperature readings, preferably with an external gauge and sending unit. Cheap "mechanical" gauges have a bulb attached as the sender, and a hard-wire copper line to the gauge. Very accurate, but a biatch to run as a dashboard gauge; however, very cheap ($20) and very helpful for temp checking. Get a handful of pipe adapter-bushings and a cheap gauge and plumb it into the water circuit.
Alternate: borrow or get an infrared temp sensor gun, like racers use for tire temps or inspectors use for home checks for insulation hot spots. Not as accurate, but if you are pointing it at a non-reflective surface (radiator tank) it will be in the ballpark. $40 at Home Depot.

Step 2 for me would be to verify that a plastic WalMart bag has not taken residence in the radiator shroud. You really should take the radiator shroud off and blow her out from the backside (can't believe I said that:-)

Step 3: hmmmmm...if the fans are running, not likely to be the relays. Also, you are not likely to hear fan differences running the engine at 3000 rpm in the garage.

 

I recently, as in about 6 days ago, did a radiator flush and coolant change. Last year I changed my balancer and all the way to the oil pump and also did a coolant change then. Last year the normal burping method worked for me with no issues. This time she was running hot almost exactly as you describe. Burped it several times and got massive amounts of air out but she was still running hot. Burped it again using this method http://forums.corvetteforum.com/c5-t...erheating.html

And all was good. Give it a try as it only takes a few minutes and a 10mm socket with extension. Good Luck!


Sorry 8VETTE7, didn't realize you posted the same link. OP, try it. Quick, simple and may just be your problem.

 

I recently purchased an 04 and one fan wasn't running. One of the 30 amp fuses under the hood was blown. Replaced it and now car runs around 190 with a/c on. Sometimes at idle it will top 200 on a hot day, but never up to 225 or over. Won't hurt to check your three fuses for the fans.
Also, if it heats up when you rev it up, the debris between the radiator and condenser may not be allowing enough air flow to cool it down when it works harder at higher rpm's.

 

Thanks for the info. I know for a fact I heard the fans kick on high a few times while it was warming up ? (had the A/C on the whole time since I know they kick on at lower temps with it on than with it off didn't have the engine constantly rev'd to 3000 just in 30sec intervals like burping procedure so at some point over that 230is number i expected to hear them kick back up into highspeed and I didn't.

I did try the burping procedure and nothing changed it did't take any more water/coolant. and the level is full to the top. I can't really see that being it though since I never opened up the system and it was fine before is this thinking correct?

I Checked both the big 30amp fuses and the smaller fan fuse all are fine.

I popped out the relays one at a time with the car running at temp to see what the fans did when I pulled 43 the fans stopped however when I pulled 44 and 45 they kept spinning with no real difference in sound or speed. They each did trigger when I pulled out and re-installed so they are doing something.

I pulled the shroud off this morning and its clean nothing blocking anything up and the fins appear clean as well.

Once again all was just fine up until about a week ago and I don't drive the car but maybe once every other weekend. So when I parked it everything was fine. did my oil and shock change and about a week later drove the car and started running hot in traffic and when stopped. however it didn't do it at first so I thought maybe my burping fixed it but about and hour later it did. Thermostat maybe???

I was reading that I can ground a terminal on relay 43 that should kick the fans into high speed. I am thinking maybe I should try that with the fans running at low speed and see what happens either that or swap the thermostat. whatcha think?

Going to head out at get one of those infared thermometers when I get a chance here today just to makes sure the reading in the car is correct but I seriously doubt that it is off that much