LT1driver

Car has small hipo motor, runs cool with airco on in town all day long, but at 65 + in runs right up to redzone or 250 degrees. It has new clutch fan. Car is high mileage with over 200K on motor. Ideas? Thanks.

BubbaJJ

Mine was doing the exact same thing. I had the radiator rodded, a high volume water pump, removed thermostat, nothing helped. I dont know why but the only thing that fixed it was an aluminum radiator.

Jvette73

I had a car that did this once before. I tried everything in the book to solve the problem except rodding the rad. Most likely the radiator tubes are plugged internally. Also could be excessive debris and bugs and whatnot clogging the rad fins, not allowing the air to pass thru the rad. Drain a small amount of coolant from the rad and look down into the cap opening with a flaslight. If you see lots of crud and build up comming out of the tubes its probably time to pull it and send it in for a rodding or a new core. You might find that a new rad is a better choice.

lou

A new radiator and water pump would be a good place to start. lou

Chuck Gongloff

Is the front air dam in place? Are the seals in place around the radiator and shroud? Overheating at speed could be caused by these items. Chuck

mrvette

I did all of the above suggestions but on my '72, the cure was removing the front tag and frame...revealing the egg crate grill in the center....
that increased front airflow about 30%....problem solved....
of course in Md. youneed go illegal without a front tag, but it's a minor offense and not likely to be noticed....I drove a '70 Lemans/GTO like that for years up there....

GENE

The Wanderer

I'm with Chuck on this one. If it doesn't overheat in traffic and low speeds, the basic cooling system must be in marginally good condition. At higher speeds all air must be directed through the radiator. You must have the lower air dam, and all radiator seals in place. Make sure the upper one makes a complete seal with your hood.

Good luck and keep us informed.

GDaina

End of june I got the 533 running. Putzing around town it was fine, on the open highway it shot up to a steady 230.

Problem was the cooling fins, on the bottom part of the radiator, had seperated from the core. Got a new core, dual fans, was running below 180, I put back the front license frame bracket and plate. Now it runs a steady 180. :cheers:

LT1driver

Thanks for the comments, I will try the radiator first since the water pump was changed not to long ago, I will let you know what works. Thanks.

Mike

yellow 72

Also be sure the "spring" is in the bottom rad hose, without it the hose can collapse at speed.........

LT1driver

Thanks all, I changed the lower hose and the problem seems to have been solved. I will take a 3 hour trip this weekend to confirm. Thanks again. :D