2004 C5 overheating
Thread Starter
Instructor
Joined: Sep 2011
Posts: 208
Likes: 2
From: Tulsa Oklahoma
2004 C5 overheating
Suddenly my car started running hot (very hot about 260) ... I slowed down to about 45mph and turned off the the a/c and it dropped to 240 for a while then climbed back up - no steam - drove home about 15 miles (manual said that was okay - of course left my cell phone at home or I would have called a wrecker) and the engine began running at reduced power (DIC came on) - are there things I can test myself or do i need a a service shop to check it out ?
Melting Slicks
Joined: Aug 2005
Posts: 2,960
Likes: 112
From: New Braunfels TX
Jump fan relays to make sure fans come on. Reduced power is normal as the PCM is protecting the engine. Look at the front of the radiator/ ac condenser for blockage. If all check out check for bad T stat. 
Team Owner
Joined: Dec 1999
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I just went through some major modifications to cool my Maggie car down and I still don't see 220 and it was a regular thing before that in fact I couldn't use my AC while driving without seeing 240....so much better now.....
GM says these cars run on the hot side but I feel better when I am not seeing 225+....thats just me
Le Mans Master
Joined: Mar 2004
Posts: 8,700
Likes: 298
From: Ft. Lauderdale Fl
Things to check:
1. Check to see that the radiator cap holds 15 psi.
2. Check/pull the radiator...make sure its clean. Also check the A/C is clean.
3. Change the fluid...do a full system flush....50/50 mix of distilled and
DexCool.
4. Check the hoses.
5. Check to see there is NO air in the system (burped).
6. Check to see the water pump is circulating the fluid.
7. Check and make sure the thermostat is good and not stuck.
The above should keep you busy for a short while.
Get back to us.
1. Check to see that the radiator cap holds 15 psi.
2. Check/pull the radiator...make sure its clean. Also check the A/C is clean.
3. Change the fluid...do a full system flush....50/50 mix of distilled and
DexCool.
4. Check the hoses.
5. Check to see there is NO air in the system (burped).
6. Check to see the water pump is circulating the fluid.
7. Check and make sure the thermostat is good and not stuck.
The above should keep you busy for a short while.
Get back to us.
