Running Hot Help
Thread Starter
Safety Car
Joined: Dec 2002
Posts: 3,655
Likes: 24
From: Charleston SC
Running Hot Help
Last week I noticed if I sit in traffic the car starts to run hot (249 when I finally noticed and shut the car down) but cools right down to 215 when moving. Both fans seem to run but slow and looking at the wiring diagram tonight it looks like they run in series or parallel depending on what Relay 3 (Mini Relay 44) does, is this correct? I plan on getting a new relay tomorrow and hope for the best but I am not familiar with the C5 cooling system and don't know what the norm is for temps parked, so if I replace the relay what temp should I be looking for if all is working correctly and any help as to if I am on the right path would be a big help.
Thanks in advance
Thanks in advance
Thread Starter
Safety Car
Joined: Dec 2002
Posts: 3,655
Likes: 24
From: Charleston SC
Ok I have been looking at this a while now and have decided if fan Relay 3 was the problem then the LH fan should stay slow but the RH fan would be high as long as fan relay 2 kicked on and if relay 2 was the problem then the opposite would happen. It looks like what ever sensor tells the PCM to activate C2 (Fan 2 and 3 relay control) may be the problem but I don't have a manual yet.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
This if from a 98 but is simular to yours.
Mini fuse 14 is powered by the IGNITION Switch.. Measure the voltage on top of the fuse in the two TEST POINTS to chassis ground with the ignition switch ON and see if you have FULL battery voltage. Check the voltage when the fan is suppose to run.
if the ignition switch contacts are damaged/burnt, it will NOT pass full battery voltage under load.
BC
Mini fuse 14 is powered by the IGNITION Switch.. Measure the voltage on top of the fuse in the two TEST POINTS to chassis ground with the ignition switch ON and see if you have FULL battery voltage. Check the voltage when the fan is suppose to run.
if the ignition switch contacts are damaged/burnt, it will NOT pass full battery voltage under load.
BC
Heel & Toe
Joined: Mar 2012
Posts: 22
Likes: 1
215 is not a good temp when "moving" stock thermo's should be around 192-194 when moving at normal speeds. shouldent go over 200 unless you are in traffic. fans should come on at 225. i would replace the stat while you are at it. 20$. they have a tendency to start closing up. mine would sit around 211-214. then later, 220, then at full highway cruise 230. just kept getting worse. new stat and all is well.
Safety Car
Joined: Oct 2004
Posts: 4,816
Likes: 132
From: Plano TX
have you checked the radiator/condenser cooling fins? When was the last time you cleaned these out? These get clogged with grass clippings,dirt, leaves,debris, and if neglected causes overheating problems.. Also,, my front airdam was bent just enough that it was obstructing airflow to the radiator, causing overheating..
Advanced
Joined: Mar 2013
Posts: 92
Likes: 11
From: Laurel, Maryland
[QUOTE=David426;1582717586]have you checked the radiator/condenser cooling fins? When was the last time you cleaned these out? These get clogged with grass clippings,dirt, leaves,debris, and if neglected causes overheating problems.. Also,, my front airdam was bent just enough that it was obstructing airflow to the radiator, causing overheating..[/QUO
I too have a C5 with over 122k miles on the engine, showing the same symptoms but instead I installed a new thermostat, the fans are good, now after about a few minutes running idle it goes hot and water bubbles back up through my reservoir. My mechanic says that it is the engine heads may be warped or cracked, any ideas?
I too have a C5 with over 122k miles on the engine, showing the same symptoms but instead I installed a new thermostat, the fans are good, now after about a few minutes running idle it goes hot and water bubbles back up through my reservoir. My mechanic says that it is the engine heads may be warped or cracked, any ideas?
Le Mans Master
Joined: Mar 2002
Posts: 8,466
Likes: 51
St. Jude Donor '17
I had a situation where the radiator hose was twisted a bit causing the fluid to have an up hill climb and potential causing an air trap.
After twisting the hose to the correct downward route, over heating was resolved.
After twisting the hose to the correct downward route, over heating was resolved.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
10 Things C8 Corvette Owners Hate (But Won't Tell You)
Joe Kucinski
10 Best Corvettes Coming to Barrett-Jackson Palm Beach 2026!
Brett Foote
Every Corvette Grand Sport Explained! (C2, C4, C6, C7, & C8)
Joe Kucinski
Grand Sport & Grand Sport X Launch Alongside All-New 535hp LS6 V8!
Michael S. Palmer
5 Reasons Bad Drivers Crash & 5 Ways to Avoid a Costly Mistake!
Joe Kucinski
