2003 C5 overheating issue

[Gerald C.]

I know the 2003 is outside the purview of the Forum, but I'm hoping folks with a C5 can help me. My car began overheating the last two times I've taken it out. One day was 102 degrees out and I was in traffic and the temp gauge went well beyond 225. Today I took the car out in 70 degrees and in a small amount of traffic and it it 220. I checked the two 30 amp fuses out and they seem to be fine. Anything I need to examine? Any other tests I should run before I bring it to a service station?

Thanks

[Terry M.]

Re: 2003 C5 overheating issue

I know the 2003 is outside the purview of the Forum, but I'm hoping folks with a C5 can help me. My car began overheating the last two times I've taken it out. One day was 102 degrees out and I was in traffic and the temp gauge went well beyond 225. Today I took the car out in 70 degrees and in a small amount of traffic and it it 220. I checked the two 30 amp fuses out and they seem to be fine. Anything I need to examine? Any other tests I should run before I bring it to a service station?

Thanks

Try replacing the radiator cap. If the cap fails to hold pressure the system will overheat. Without some specific tools, replacing the radiator cap is the easiest and least expensive "throw parts at it" option.

Is the coolant flowing out of the system, or the gauge just showing high temperatures?

Have you flushed/changed the coolant recently?

[Duke W.]

Re: 2003 C5 overheating issue

If the AC isn't on I don't think the fan(s) engage until about 220. On a hot day let it idle with the AC both off checking temperature until they come on.

If the AC is on they will come on either based on engine temp or AC pressure .

Circa 2003 I had a C5 press car for a few days that I drove to a Lake Tahoe Regional. I got so paranoid about the 200-225 engine temp climbing up the grapevine in slow traffic on the return trip that I turned off the AC, but I really didn't have to. Modern cars are set up to run hot. It helps keep emissions low.

Duke

[Tom B.]

Re: 2003 C5 overheating issue

try getting under the front of the car and ck for dirt and debris on the front of the ac condensor or radiator.These cars are notorious for dirt and debris build up in that area making them run hot. You may have to get it up on a lift or jack it up to see this area . I usually use a water hose if you have decent pressure or gently with a pressure washer. It has cured 95% that i have seen with running hot. Do ck and make sure your Radiator fan is operating also.

[Edward J.]

Re: 2003 C5 overheating issue

Jerry are both cooling fans in operation when A\C is on? They also have have a high speed and low speed operation I believe, Check the low speed operation with the engine idling ,with A/C off. If you know someone with a Scan tool they can check the operation of the fans, they have the ability to turn them on to check. These newer cars will run upward of 230 with traffic and A/C on And hot outside temp.s. Few simple checks also is to check coolant level when cold, Also as noted by Tom check front of Condenser for leaves and debris sometimes leaves get stuck between the Radiator and condenser, I like using air pressure to clean. The cooling fin are a soft aluminum and fold over so be careful with to getting to close with air or high water pressure.

[Carl N.]

Re: 2003 C5 overheating issue

try getting under the front of the car and ck for dirt and debris on the front of the ac condenser or radiator.These cars are notorious for dirt and debris build up in that area making them run hot. You may have to get it up on a lift or jack it up to see this area . I usually use a water hose if you have decent pressure or gently with a pressure washer. It has cured 95% that i have seen with running hot. Do ck and make sure your Radiator fan is operating also.

Tom is correct, I have a ,98 and drive it almost every day. Roads in Texas are dusty so I clean out front of radiator and condenser with compressed air every fall. Also make sure all the "wicker bills" under the bumper are in place as they are necessary to insure proper air flow.

[Gerald C.]

Re: 2003 C5 overheating issue

Thanks everyone. I'll try these methods to try to solve the issue.