I have a '01 Conv 6spd. When I was sitting in traffic on I-95 yesterday, it looked to me like it was going to overheat, so I blasted the heat with the windows open and it stabilized. It's done this before when the A/C was running, but yesterday it was 30F out, no A/C. Seems like the coolant level and auxiliary fan are ok. Anyone else have this problem? How close to red should the temp get sitting -- maybe it's just me, but it was pushing 230 and normally runs about 180.

 

More than likely , you have leaves and debris blocking your condensor and radiator...lots a people suck a plastic bag up there too... this is fall in most parts of the contry, its possible you have alot of leaves up there..

 

Did you check to make sure nothing got sucked up into your radiator, plastic bag, etc.? These cars make great vacuum cleaners!

 

I hadn't thought of that (thanks), but I just checked and nothing major. A few leaves, some dirt here and there.

 

Running hot at speed will usually point to a radiator blockage issue. It could be idle too if severe, but your temps while moving will also be abnormally high.
Running hot at idle is usually a coolent level or possibly a water pump (flow) problem.

230 after a long idle is considered normal, however in 30 degree ambient temps does seems a little too high. Mine routinely hits 230 idling in hot weather, but low 220's is more the norm in winter.

The 2nd fan doesn't even come on until 235, so you were probably not in danger of overheating,. Also, (generally speaking), turning the A/C on tends to lower temps on these cars, as it turns a fan on at all times. You might not notice it in super-hot weather, but in moderate temps, this will be the effect. Although if it was 30 out, your A/C won't even turn on (below 35f).

If your thermostat and fan programming is stock, no way do you see 180 after extended idling, even in subzero temps. On the road, sure, but not idling.

I don't have an easy answer for you, just considering all involved and what's likely NOT the problem. What you've described is considered normal, but if you often study the temp, and this is a sudden rise from norm, then something likely is wrong.

 

It could be nothing more than a bad sending unit.

 

Thanks for the help everyone. I'll idle car for an extended period tomorrow and see what happens -- especially to see if it gets to 235 and the second fan starts. But it sounds like the problem may be with the driver.

 

Could be a sticking thermostat.

Anything recently done to cooling system, could be air in system.

Coolant cap tight? Might not be building pressure so coolant starts to boil.

 

 

Had that problem and the #1 fan did not come on at 226. Relay was the problem!

 

Questions: Since the C5's runs hot.... Do you guys recommend switching to a lower degree thermosat, like to 180? And by switching to a lower temp thermosat, does it effect the performance of the engine? Or interfer with the smog emission?

Thanks

 

I use a high preassure air hose with a 2foot long wand to blow the leaves, dirt and other garbage out of the raidator and the a/c condenser. That witha 180 thermostate I dont have over heating problems what so ever.

I think the key was keeping the radiator fee of debris not the t-state.

 

have a '00 a4 coupe...normal (cool) running is 192...traffic will run it up to around 220 w/ac on, and a couple higher w/ac off (both fans run w/ac on)...my understanding that lower thermostat doesn't really affect temp...temp is a function of radiator, coolant, water pump and fan...see you're in cary...i was in raleigh for training a couple of days the first week in december...drove the vette one day...very mild, balmy day...got stuck in the dreaded knightdale choke-hold on the way in...no temp problems...if you drive your car a lot (mine's daily), gotta keep the radiator clear of debris...

 

I've never seen over 205 in mine. I keep AC on all the time. I used to wish my C4 would get as low as 230...

 

It depends a lot on the climate.

In hot weather, a Tstat makes little difference. Once the car warms up (a matter of a couple minutes), the Tstat remains open all the time, and the fans and radiator are struggling to keep things cool.

In very cold weather, on the road, you can actually watch the temp gauge bounce up and down as the Tstat keeps opening and closing. It's literally trying to keep the engine warm enough.

This is why a 160 stat in a cold weather car is not a good idea. Unless idling a long time, the engine will never reach ideal temps in cold weather. Running an engine too cold is much worse than running a little hot (220-230) IMO. You need to see at least 200 degree oil temps to burn off condensation and prevent sludge buildup, even with synthetic oils..

 

Colder thermostat only makes the engine take longer to get up to temp. Waste of time.

 

Wow a 10 year old post rises to the top of the postings.......

 

WOW why dont they just delete these if they are such a problem?

 

They should get LOCKED after so many months not deleted.

 

When a problem comes up, an OP should start a new thread.