Lti running hot?
In Old School's case, the original high-mile radiator was simply worn out; however, in many LT1 cars, the culprit can be found in other parts of the cooling system and factory air ducting. If you are seeing higher-than-normal temps, be sure to check for these problems before assuming the radiator is shot:
Leaky cooling system
Malfunctioning radiator cap
Obstructed radiator/condenser area (leaves or other debris)
Broken/missing factory air dam
Air in system: bleeder screws by thermostat housing
Incorrect LT1 thermostat: use long 160-degree version
Inaccurate coolant temp sensor on water pump
Inaccurate temp gauge sensor in driver-side cylinder head
Bad fan fuses/relays in underhood fuse box if fans malfunction
For testing purposes, we enlisted a Tech II Scan Tool to monitor coolant temperature. With both the original and Fluidyne radiators, the Z28 was warmed up and driven around for several minutes before coming back to the shop for the temp reading. Both tests were performed with the cooling fans and air conditioning on.
Original radiator test - july 2006
Outside temp: 100 degrees
Coolant temp: 230 degrees
Fluidyne radiator test - august 2006
Outside temp: 94 degrees
Coolant temp: 170 degrees