I did the following maintenance items today then ran into trouble with the car overheating - temp gauge buried in the red and digital gauge showing a temp of XXX. I started the day by removing some grass and debris from the radiator air intake - brushed away using my hand and a toothbrush. Next up was a new AGM battery, and while the battery was removed I cleaned the passenger side utter. I did have to remove the battery tray as I dropped a socket. After buttoning everything back up I took it for a drive. About 10 minutes into the drive the gauges showed the temp at/over 260 degrees. Thankfully I was close to home. What could I have done to cause the problem as temp has never been a problem.

 

Sounds like the temp sensor has failed. Did it smell hot when you stopped?

 

Yes it smelled hot and the coolant reservoir was very hot to touch. Since this was not an issue before, I keep thinking it has to be related to one of the maintenance items I did as the problem occurred immediately after the work was performed.

 

Maybe coincidence. I've had a bad ground cause the temp gauge to peg before. Maybe a sticky thermostat?

 

Overheating in 10 minutes... sounds like an air bubble in the system. BUT you didn't say you changed coolant, did you?

 

If you got that much in front of your radiator I guarantee all the fins are plugged
1x a yr, from the backside of the rad. I take a garden hose and gently flus (from the backside) all of them out, can take awhile. Compressed air afterwards a plus. Youd be surprised....do the condenser too youll notice your ac gets cooler quicker.
I do this with every car.....even a car with a clutch fan youll notice it wont come on as often.

 

No I did not change the coolant.

 

Moved to C5 Tech.

 

You need to determine if your fans are coming on, does the car overheat on the highway? The fans are turned off at 35mph on the highway, if the car's temperatures increase on the highway then the radiator may have debris in the cooling fins, also check your coolant level.

 

overheating can be a sign of a small coolant leak. The pressure is needed to prevent the coolant boiling, as the polling point increases with increasing temperature. A couple signs, white exhaust smoke that disappears may mean a blown head gasket. Smelling coolant under the hood means a system leak, The reservoirs are known to crack, coolant hoses get age related cracking, water pumps develop leaks, etc.

 

Is there a chance that you accidently hit or disable the fan relays?? If the car is only getting hot at under 35 mph or at idle, it is your fan(s) not coming on. Does the fan come on when you turn the A/C on? Does the car over heat at highway speeds?

 

Thanks everyone for the input! Will be looking at your suggestions this weekend.

 

I had the same problem overheating I had noticed while at a traffic light that the car started to increase (rather quickly) in temperature, then as soon as I started to drive again it would return to normal. This happened only a few times then all of a sudden it would start to rise at idle all the time and eventually even as I drove it would overheat idle driving or whenever the car was started eventually almost immediately it would overheat. It was a slight bit low on coolant so I filled it a little past the full cold mark and after starting it again it would immediately overheat and it spilled or leaked coolant after that (coolant was overfilled) I then installed a new thermostat thinking the old one was stuck closed and still it overheated. After researching this forum I came across several similar situations as mine. So as to the history of what others like me where experiencing I removed the radiator, not realty too bad of a job if you jack the vehicle from the front and have access to the underside of the car. There are a few YouTube videos that you can access to help you understand the procedure. After I removed my radiator it was so severely clogged with debris that you could not see through it. I debated about a new one or just cleaning this one, I decided to purchase a new one. I was able to find the exact AC Delco one which was rather costly $416 shipping and tax included (found exact one under $300) later as I was looking elsewhere after I placed my order, it was too late all I could do was regret buying too soon so a lesson learned and will be more patient next time. There are several you can purchase that are all aluminum with no plastic but mine required the inverted flare fittings for the transmission cooling lines that where of a large diameter so no one manufactured one as I needed not for anything under $700. My car is a 2002 with 75000 miles so there was no way i was going to reinstall a 20 year old radiator back in it. When it came in I had reinstalled new radiator in which only took about a two hours by myself. Just be aware that the fans and the AC condenser has to reclip into all the brackets (four clips for the fans and four clips for the AC condenser) took a bit of finagling but it went back without too much trouble. Refilled cooling system and everything has been great since. Please not that these cars are literal vacuum cleaners for sweeping up debris off the road. The way it is designed the radiator and AC condenser are placed at an angle as to affect the airflow into the system as you are driving and a lot of debris over time will clog it up and affect the ability for it to cool itself especially at idle and eventually while driving. The fans will come on but if unable to circulate air through the radiator it will quickly overheat. I cleaned out the AC condenser very well with compressed air and a special made water nozzle for cleaning in tight spaces, I purchased these from NAPA about $40 for the set and will leave exactly what they are in the end of this post. I would recommend that C5 owners about once every two years remove the plastic radiator cover (only 4 10 millimeter bolts) and clean with these nozzles to keep the debris at a minimum. Thanks for all the post and advise to all who guided me with their past experiences with the overheating issues I was having. The nozzles are named "Radiator Genie" and can be purchased from NAPA, Amazon, or Tractor supply from $35 to $40
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