Mr.E.G.

Gentlemen,

I will start by saying that I searched, only now I may be less certain about what to do before I searched...



I recently purchased a 2003 C5 Z06. It has bolt-ons and about 24,000 miles. I was sitting in my car in a parking lot with the AC on a few days ago (it was over 100 degrees out) and I saw the analog coolant temp gauge start to inch forward. It go up to about 225-230ish and I shut the car down in an abundance of caution.

When it was time to hit he road, I started it up and it ran at its normal (for my car) 190-200ish degrees while in motion, but about 30 seconds after I stopped at a light,it would start getting warmer. It has not gotten as warm as 225-230 like I first experience, but only because I have turned it off before it got there.

I have read several threads about similar issues and some people have indicated that the fan doesn't even normally come on until 235-240 degrees. First question, does that sound right? I don't know if I have the ***** to watch my car's temp climb with the hope that it will level off.

Further, I have read that it's a good idea to blow the crud out of the radiator and AC condensor, so that's a no brainer, but what else should I do?

My gut instinct is to not screw around and, at a minimum have a shop look at the car. Or go headlong into paranoia and have the radiator fan replaced, radiator flushed, clean the aforementioned crud, maybe a new thermostat, and then see where I'm at.

PeteZ06

Get your radiator flushed and a 180 or 160 degree thermo to start. You can also get your car tuned so that your fans turn on at lower temps.

But as a FYI.. seeing those temps under the circumstances you described isnt anything unusual.

beastyz06

I had same dilemma after I purchased 2002 C5Z but, according to the manual, articles in the forums, everything is normal.

Coolant temperature does to up to 220F -230F with normal driving condition.

So I've purchased 160 t-stat and will replace to bigger radiator later on.

pewter99

sitting there and seeing temps climb concerns me....check to make sure your fans are working properly....I am wondering if your water pump is not functioning up to par

2K3Z06

blow out the radiators with compressed air... you will get a lot of dirt out of there. check between the ac condenser and radiator.

and those temps are normal sitting in traffic, they will go down once you get the car above 30MPH.

Mr.E.G.

Thanks, everyone. I believe you guys, but it is not fun seeing that needle climb.

Mr.E.G.

At what point should I definitely shut it down?

PeteZ06

When it gets in the red.

Get a lower temp thermostat and do a radiator flush.. it'll stay around 200 then.

laurent_zo6

Factory temp settings are low speed on at 226 degrees and off at 219 degrees. High speed on at 235 degrees and revert to low speed at 226 degrees. As stated both fans run at low speed and high speed and fans are commanded off by the PCM when the
vehicle speed exceeds 35 mph.
You can force low speed operation at 185 degrees by turning on the AC.
High speed operation with AC on is still 235 degrees.

Mr.E.G.

That's very good info. Thanks.

So, if understand correctly, if the car gets to 235 and I'm stopped, the fans should be going full blast. If it gets above 235 by any appreciable degree, that's probably a sign of trouble that I should investigate further. But I f it gets up to 235 and the fan comes on / it starts going back down, then that is nothing to worry about.

Sound like a plan?

MX621

You check if the radiator/condenser is blocked with crap? First time I looked I couldn't believe how much debris was clogged up there u use an air compressor yearly to blow it clean

Mr.E.G.

I haven't yet. I'm working 12 hour days (at a minimum) for the rest of the week.

It'll make a nice weekend project... Like my half-finished garage renovation, my half-finished deck, and my pool cleaning project. Haha.

I'll keep it in the garage until I have a chance to diagnose it.

bob22z06

Ha ha I like what u said about your half ....lol...my half done some major yard cleaning too at my house too while im working late every day too ..lol....but I get stuck with other projects on the weekend anyway. ..hey don't sweat the temp rise on your Z ..mine does stay in mid 200 range all the time when im in traffic too..drops when I start moving even I don't have front center air deflector just ordered last week been driving with out it for a while will see what happens when I put it on

RogerZ06

Sounds normal to me.

If you saw 220+ while highway driving you have problem.