# Running Hot - Radiator suggestions - 66 GTO 389 4SP



## oki_namiinori (Dec 29, 2019)

Hi All,
Looking for a suggestion on a new radiator for my 66 GTO 389. I know she's a bit tired and I have already replaced the thermostat. Was looking at the JEGs aluminum models and am open to suggestions.


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## O52 (Jan 27, 2019)

Cold Case seems to be a favorite here.

Make sure you get the right size. Two different sizes depending upon whether your car has factory AC or not. They are not interchangeable.


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## oki_namiinori (Dec 29, 2019)

I talked with Cold Case and started down the path to replace the radiator with the new version with electric fans. Starting having regret, so I cancelled that order. So my next question is radiator fan clutch or no fan clutch? Currently, I do not have a fan clutch installed.

Also, my installed fan is 17" in diameter and Summit suggested an 18" fan.

Currently in the cart:
Radiator GPG-34 (No A/C)
18" Fan GBC0560
Shroud 00T221R


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## Sdpepper (Jun 3, 2021)

oki_namiinori said:


> I talked with Cold Case and started down the path to replace the radiator with the new version with electric fans. Starting having regret, so I cancelled that order. So my next question is radiator fan clutch or no fan clutch? Currently, I do not have a fan clutch installed.
> 
> Also, my installed fan is 17" in diameter and Summit suggested an 18" fan.
> 
> ...


I also recommend Cold Case. I went with their two core dual fan model and very happy with the effect it’s had on my car. I also installed a hi flow water pump and thoroughly flushed out the old antifreeze put in new antifreeze and used distilled water.


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## PontiacJim (Dec 29, 2012)

oki_namiinori said:


> I talked with Cold Case and started down the path to replace the radiator with the new version with electric fans. Starting having regret, so I cancelled that order. So my next question is radiator fan clutch or no fan clutch? Currently, I do not have a fan clutch installed.
> 
> Also, my installed fan is 17" in diameter and Summit suggested an 18" fan.
> 
> ...


Looks to be the correct size. The 1"-1 1/4" tubes are what you want.

Note in the reviews that the bottom tank may not fit like factory. The factory radiator is 3-core, the aluminum is 2-core and may be slightly narrower. Should be easy enough to make a fix as the bottom of the radiator tank sits into a rubber insulator.

The radiator is said to use a stock fan shroud/ The stock fan shroud inside diameter is 19 1/2" (but aftermarket says 20 1/2" which may be more accurate) and uses the 18" diameter 7 bladed fan and fan clutch. You want 1" of clearance between the fan blade and the fan shroud and that the fan blade sits at least an inch into the shroud for maximum cooling benefits.

The fan shroud you have listed says it is a factory replacement with the 18" fan.

However, the 7-bladed fan is for AC and needs to be used with the clutch. Here it is listed by OPGI:









Fan Blade, 1961-67 Bonn/Cat/GTO/GP 326/389/400, 18", w/ AC @ OPGI.com


Fan Blade, 1961-67 Bonn/Cat/GTO/GP 326/389/400, 18", w/ AC. Manufactured to original specifications for cars equipped with air conditioning, this reproduction …




www.opgi.com





If used, you want the Hayden fan clutch. Here is one at Rockauto. You can read up on it and they give you all your dimensions. This one is the Heavy Duty type, but Hayden has Standard duty as well.





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More Information for HAYDEN 2797






www.rockauto.com





Your other option is an 18" non-AC fan, but you may need a fan spacer to move the fan out into the shroud - they make these as well.

I had a factory steel 4-blade fan and new 3-row factory style radiator. It ran hot. Replaced it with a flex fan and it ran cooler. Did not have a fan shroud at the time. So a flex fan could be an option.

Read through this forum post which can give you a lot of information in making your decision:





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Hayden 2747 & 2797 fan clutches - PY Online Forums - Bringing the Pontiac Hobby Together


Hayden 2747 & 2797 fan clutches Heating & Cooling TECH



forums.maxperformanceinc.com


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