Jump to content
Forums Gone... but not forgotten!
Pontiac of the Month

JAH11's 1968 GTO

2024 June
of the Month

  • Rev up your passion for Pontiacs and join our vibrant community of enthusiasts!

    Whether you're a die-hard fan of classic muscle cars or you've got a soft spot for sleek modern models, you've found your home here at Forever Pontiac. Our community is dedicated to celebrating everything Pontiac, from the iconic GTO to the legendary Firebird and everything in between.

    Unlock access to expert advice, stunning photo galleries, engaging discussions, exclusive events, and more!

    Start your Pontiac journey with us today!

    Sign up now! 🏁

67 GTO has tendancy to run a little warm

Recommended Posts

This was a post from somebody on the facebook page and since they "liked" my post when I said I would bring this issue up in the forums on their behalf, I'm assuming that is what he wants me to do lol

anyways he says

Question, My 67 GTO has a tendency to run a little warm in the summer and especially when I get stuck in traffic or at a red light. The engine has recently been rebuilt and was stroked a little and I have a desert cooler radiator in it. I also put a little fan in front of radiator. Would an aluminum radiator make enough difference to invest in one?

Very frustrating to take her out and worry about overheating. She will get about 10-15 degrees hotter than normal.

here is the FB post


Link to comment
Share on other sites

Tired of these Ads? Register Today!

Need a lil more info. Is he running a fan schroud? This is a common mistake. What thermostate is he running? The fan installed in front of the rad. Is it blowin through the rad? If he's using an electric "puller fan" it could be installed backwards and the fans are fighting each other. Is it the correct rad for the engine?? or the car? Different rads fit the same model car. A 305 will use a much smaller core than a 455 ect.

Link to comment
Share on other sites

I would also ask what is the coolant mixture? Is it old antifreeze? Is the coolant at the proper level? Some people believe in running distilled water with "Redline Water Wetter" which is a chemical that reduces the surface tension of the water thus creating more cooling. That's fine in warmer parts of the country. Here in the north I am still a fan of 50/50 water to antifreeze.

I also would see if perhaps the antifreeze is getting a tad old and the system could stand being flushed. I installed a radiator overflow bottle in the Lemans after the 455 was rebuilt to a 462. The radiators of the day had a hose that dumped hot antifreeze on the ground when the radiator cap pressure was reached. Today all cars have an overflow bottle to collect the hot fluid and pull it back when it cools off. This eliminates antifreeze being dumped on the ground which can eventually leading to overheating.

I also run a wide mouth 180 degree thermostat from Mr Gasket to promote more water flow throw the cooling system. This thermostat is said to flow 20% more area to get more water through.

Finally, I run a factory copper-lead 4-core radiator. It is designed to run with a big motor with power steering and air conditioning.

I also agree with JUSTA6's comments as well. One more comment I would add is what kind of fan is this '67 running? A straight 4 or 5 blade fan or a thermostatically controlled fan? All Pontiacs from the factory ran thermostatically controlled fans. Perhaps that might be part of the problem too.

Link to comment
Share on other sites

  • 2 weeks later...

Thanks folks! I did put aside mouth thermostat. I have an over flow tank on the radiator. I have not checked or changed the anti freeze in a couple of years, and I haven't checked that bottom radiator hose. I plan to check all in the spring when I get her back out before I invest in an aluminum radiator! My anti freeze is straight by the way!

it is possible to put the thermostat in backwards?

Link to comment
Share on other sites

Straight antifreeze?i prefer mine to be bi..50/50. distilled water/antifreeze.i think ya mean the stuff thats already mixed?

He must mean pre-mixed. NOBODY runs straight antifreeze.

Link to comment
Share on other sites

  • 1 year later...

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Tired of these Ads? Purchase Enhanced Membership today to remove them!
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.