2003 Z06, 38,000.

Yesterday while driving in stop and go traffic, I hear a beeping and see check gauges on my DIC, I look at the temp gauge and it is in the red at just shy of 260 degrees!

As I notice this, I turn out of the traffic and am going 35 mph and the temp starts coming down and within +- 30 second it's down under 200 degrees. Temp outside was +-65. Problem didn't happen again.

I have noticed a year ago, when in stop and go traffic (something I am seldom in) the thermostat has jumped up to 220-230 degrees and then within a minute could be back down under 200. This has happened a few times in the past (that I have noticed)

When I have noticed this, the temp gauge kind of moves around a little before subsiding to normal temp- starts coming down stops goes up a little, comes down again etc.

My first reaction is to replace thermostat, I assume it's cheap and easy.

Anyone had similar problem?

 

Sounds like a thermostat problem to me, when it heats up and cools back down that fast it usually is the thermostat becoming un stuck/opening

 

Here's more info:

Just took the car out for a 20 minute ride. Once warned up, temp is around 190-194 degrees, which seems normal. Then I parked the car in my driveway and let it idle (800rpm) and watched the temp climb to 239degrees before both fans kicked on. Temp went down a little but then seemed to settled in at 241 degrees for a couple of minutes before I shut the engine off.

Is this normal?

 

Just taking a shot here, but this is a problem that used to be common in cars 30, 40, 50 years ago. If the temperature is holding at 190 - 195 while driving, and then goes up in stop and go traffic or while idling, it usually means the water pump is not moving enough water. Try your idling experiment again, but this time, after the drive where it hold temp, and then idling and temp rises, just put your foot on the gas and hold the engine at around 2000 to 2500 rpm for a couple of minutes and see if the temp comes down. If so, it's just a matter of the water pump not moving enough coolant through the system at idle. If the fans are kicking on, they should move enough air to cool the system, but you need to move coolant through the block to get the radiator to do its job.

It never hurts to change the thermostat, though I doubt that's your problem. You wouldn't be holding 190 or so while driving if it was stuck. Flushing the system may help improve flow, but my guess, it's just a function of the system at idle. I remember when I first started driving, having to put those old cars into neutral and rev the engine when stuck in traffic to keep them from overheating. New water pumps are more efficient, as are the electric fans, but a big engine like ours puts out a lot of heat and needs good coolant flow to move the BTUs out to the radiator.



p.s. It could also be a sign that you have a partial clog in the radiator. At speed, you may be flowing enough to cool, but at idle, blockage is preventing sufficient coolant flow to keep you cool. Flow testing won't show a partial blockage very well. You may need to have a radiator guy open it up and check the core for you. And it doesn't hurt to check your belts as well to be sure they are turning the pump properly at idle, and not slipping. And check the radiator fins to be sure they are not clogged with crap from the road.

 

also check for debris between the radiators. This can get debris up there that blocks air flow.

 

My zo6 started to run hot after i put a cam in it. In traffic, temp. went over 245. (I had a cooler thrmo. installed). Still running hot, I found out when I put the heater on high, the temp. did go down to 200.

But that was not a sollution, driving around south fl in 100 degree's with the heater on. So I put my car on my lift, removed my fans and blew out my radiator and condensor. It was clogged with dried up grass.

I have been driving it now for almost two weeks, and it has been a steady 200.

 

i'm in south fla and when i sit and idle my temp will rise. i've only let it get to 220 before i turn on the ac. that makes the second fan run. i can idle all day as long as the second fan is running. i think you can program it to come on earlier but thats how i deal with it so far.

 

I went out last night and shot water through the backside of the radiator. some small amount of leaves came out. a few stems as well.

I spent 1.5 hours on it, but the problem has not gone away.

I am thinking about taking a look at the thermostat as well. I may pull the radiator out if I crack the thermostat out and try to get all the crap out of it.

 

Yes: I found a page from a newspaper in the radiator compartment. I make it a practice to check the radiator compartment on a regular basis. Question has any one considered placing a wire grill over the radiator inlet to keep paper and plastic bags out?

 

My 2002 Z06 was over heating due to obstruction in the radiator compartment: I found a page from a newspaper in the radiator compartment. I make it a practice to check the radiator compartment on a regular basis. Question has any one considered placing a wire grill over the radiator inlet to keep paper and plastic bags out?

 

Yes, there are debris screens available at some of our supporting vendors. Or you can DIY.

 

I recently purchased the intake grill from ELITE ENGINEERING when they had them on sale. It's an easy installation and looks oem.
I made a similar screen for my '96 Impala SS years ago...it's very crude in comparison.

 

Thank you

 

Thank you