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Discussion Starter #1
I have a 1967 GTO and am having cooling problems. The 67 service manual says all 67 Pontiacs had cross flow radiators. Pictures I have seen all seem to show down flow radiators. My current radiator is a harrison down flow. Any suggestions? What was actually stock??
 

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All '67 and back GTO's had down flow radiators, with an upper and lower tank. The stock rad was a Harrison. I've had both the Harrison 4-row radiators in my GTO's re-cored ....the '67 once and the '65 twice.
 

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Discussion Starter #3
Thats what I thought. Thanks for the reply! Thinking about going to an aluminum radiator this year, but not absolutely sure yet....
 

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I have found that with Pontiacs, pretty much every element of the cooling system has to be in good shape for optimum cooling. Thermostate, water pump clearance, water pump impellor blades, proper fan, fan clutch, shroud, shroud clearance, and a good rad core. A super duper aluminum radiator is killing a spider with a hammer...overkill. It will mask other potential cooling problems due to its high efficiency. As a side note, they are light and efficient , and work very well for modified engines that make a lot of power.
 

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Give a good look at the fan clutch if you have rulled out the usual suspects. Almost all of the cheap aftermarket clutches are never up to the job. They end up in a lot fo cars due to the fact that a quality GM clutch is often three times the price of an aftermarket clutch and they can cause all sorts of overheating problems that are hard to track down.
 

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Discussion Starter #6
I put in a new Hayden super duty clutch fan at the end of last year. My radiator is a 4 core that has been boiled out and re cored. The fan (7 blade) is sitting properly in the shroud. I can run on the freeway or regular streets at 195, but, when I get caught in stop and go traffic, I balloon to 225, even 235.....I even have an aux. fan!!
 

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Well jsgoatman from your post I would have to point the dirty end of the stick right at that Hayden clutch. Just my vast years of experience. Finding a good aftermarket fan clutch is pretty hard. Out of all of the ones I have seen installed 90% either stay locked up hot or cold and turn your cooling fan into a propeller which in turns makes your car feel like your towing a trailer or sound like a 747 at take off!
Factory fan clutches are outragiously expensive which drive the aftermarket sales of the derivative that usally sell for a quater of the price.
If what you have posted in your thread that your radiator veins are clear and flowing and the fan and shroud are both installed properly then add in the fact that the car runs at proper tempature when the motion of the car is moving air through the radiator I could only blame the clutch. New or not 90% of them just will not work.
There are actually several threads on Hayden clutches not working properly brand new out of the box. I have no idea if the GM part is still avalible but the number you need is part number 4779957. It fits all Pontiacs 59-67 reguardless of engine A/C or heavy duty cooling so it might still be avalible as an AC Delco part. Good luck and let us know how you make out.

Edit: Just did a check of the net and found multiple bad reviews of Hayden fan clutches.
 

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Discussion Starter #8
The fan clutch I just replaced was the original GM part. I put the Hayden on at the end of the season, so, I only had a couple of weeks with it.....I kept the original, but I changed that one because of the overheating problem. I will keep an eye on the new one once I take the Goat out of storage.
 

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Whern a Pontiac Service Manual refers to a "PONTIAC" this usually means a 'full size car' ( catalina, Bonneville, etc)....The GTO is in the " A-body section" as some systems differ. The 67 GTO was built with a DOWN FLOW RADIATOR. Eric:cheers
 

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And, I'll add this to the confusion: a lot of new fan clutches are calibrated to come on at 240 degrees or so, because they are designed for newer, emission controlled trucks/cars that run at 220-230 as standard operating temp. So, for an old GTO, they need the thermal spring adjusted so they activate at 200 or so. There are detailed procedures on how to do this on the internet. If you are getting hot in traffic and it cools down on the highway, you are definitely not pulling enough air thru the radiator with your fan, and that is the problem, as 67coupe pointed out.
 

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Discussion Starter #12
If, and I emphasize IF....I were going to replace the radiator with a new aluminum downflow rad, which one would be suggested??
 

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Griffin makes some of the best out there but they use the cross flow design. They also are not drop in fit either. They are listed by dimensions and number of cores.
 

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67 gto radiator problems

I read several of the comments about temperature problems... I have a 400 engine that always go hot until I read in the forum about the cavitation problem. when I took the metal plate and moved it closer into the impeller the heating problem went away. Now I am getting ready to put the clutch fan back on to the car. hope I do not have the problems I keep reading about.
 
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