# 66 GTO Cooling Problems-advice



## ottfive (Jul 23, 2012)

cooling question 66 GTO
Which Robert Shaw Thermostat should I use 160 or 180 ?
I have a 428 1968 engine w/tri power
I purchased a aluminum radiator
Has any one used a antifreeze additive?
Where can I purchase a shroud for my alum radiator?
Also has anyone ever tried vinegar/water to flush radiator system?
Appreciate any help in getting my GTO to run cool!


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## 05GTO (Oct 6, 2004)

I use a 180 degree t-stat on my 66, it ran hot until I purchased and installed a Mr. Gasket Fan Spacer Kit between the fan and the water pump. My fan is within 1" of the radiator and the car has not overheated since adding that $15.00 part.


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## facn8me (Jul 30, 2011)

What is your actual problem? Yes an alluminum radiator will help. Yes a fan shroud will help. I bought one from ames. I run a 160* thermostat but honestly the rest of the cooling system sets the temp. T stat is mainly for heat in the winter. I have never tried vinager and water. Yes water wetter works to an extent.


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## BearGFR (Aug 25, 2008)

Biggest secret to cooling a Pontiac is getting the water pump plate clearance right. Search on here for posts on how to.


Bear


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## Chris-Austria (Dec 23, 2010)

I have almost the same engine (428 with tri power). That's what I changed on the cooling system:

1. 2 row aluminium radiator 3"
2. aluminium high flow waterpump
3. correct waterpump plate clearence and new waterpump sleeves
4. big electric fan with shroud
5. thermostat high flow 160°

With this setup even at 100°F outside it stays as cool as I want it to. I set the fan to 190° so it never gets hotter than that. The ignition can also be a source of the engine to overheat!

If your car gets hot in traffic you probably need a good shroud and fan + correct ignition timing. If your car gets hot while driving fast the fan is probably not the source of your problem.
With additives I never had a big difference.. for me it's just a waste of money.


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## ottfive (Jul 23, 2012)

*Thanks for the info! I do have current fan about 3 in from radiator*

Thanks for the info! I do have current fan about 3 in from radiator


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## jday240 (Feb 10, 2007)

I've had a similar problem with my 400 overheating and am still working it out a little at a time. I just purchased a $10 spring that fits inside the lower radiator hose. It keeps the hose from collapsing due to suction (created by the water pump I guess). I currently run a bottle of Water Wetter along with 50/50 coolant mix and a 160* thermostat and still see 210* while driving highway speeds. I will soon be adding an electric fan just to see how it affects the temps. Good luck and keep us posted.


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## Chris-Austria (Dec 23, 2010)

I've seen shrouds at summitracing and yearone that should fit your radiator. With the shroud and a fan spacer your cooling should work a lot better.
With the high flow aluminium waterpump my cooling temps went down 10-15°. The thermostat didn't change anything and the electric fan with the shroud has decreased the temps up to 40°. I think fan and shroud have the biggest influence on your engine temps. But it's important to first check the divider plate, the sleeves and the timing. If these things ain't right the best fan cannot cool your engine!


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## ottfive (Jul 23, 2012)

*ottfive*



Chris-Austria said:


> I've seen shrouds at summitracing and yearone that should fit your radiator. With the shroud and a fan spacer your cooling should work a lot better.
> With the high flow aluminium waterpump my cooling temps went down 10-15°. The thermostat didn't change anything and the electric fan with the shroud has decreased the temps up to 40°. I think fan and shroud have the biggest influence on your engine temps. But it's important to first check the divider plate, the sleeves and the timing. If these things ain't right the best fan cannot cool your engine!


I appreciate all the info from everyone, I will start on each item to see which one works! I will keep you posted! This is a Great Forum!


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## ottfive (Jul 23, 2012)

*ottfive*



05GTO said:


> I use a 180 degree t-stat on my 66, it ran hot until I purchased and installed a Mr. Gasket Fan Spacer Kit between the fan and the water pump. My fan is within 1" of the radiator and the car has not overheated since adding that $15.00 part.


which spacer did you use 2" or ? I am using stock waterpump w/stock fan
Thanks!


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## Old Goat 66 (Jan 9, 2012)

I think way back someone told me not to use a fan spacer with a clutch fan because it may not be balanced properly.


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## geeteeohguy (Feb 2, 2008)

A fan spacer used in conjunction with a clutch type fan will put undue strain on the water pump bearing. It's a lot of weight way out there, where you don't want it. It's not normally done. Better to use the right fan/shroud combo, IMO.


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## BearGFR (Aug 25, 2008)

Again, you can keep throwing money at it buying parts that aren't going to make much difference, or you can address the real problem and make sure your plate clearance is right. If that's off significantly, you can't -spend- enough money to keep it cool because the pump just isn't going to move enough coolant for the rest of the system to work.

And, getting it right is only going to cost you some time and maybe a couple of gaskets.

Bear


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## allpawl66 (May 9, 2008)

What impeller is on the pump that you are using ? Stamped / cast long vane ? Timing / lean on fuel has a lot to do with temp. as well .


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## Instg8ter (Sep 28, 2010)

BearGFR said:


> Again, you can keep throwing money at it buying parts that aren't going to make much difference, or you can address the real problem and make sure your plate clearance is right. If that's off significantly, you can't -spend- enough money to keep it cool because the pump just isn't going to move enough coolant for the rest of the system to work.
> 
> And, getting it right is only going to cost you some time and maybe a couple of gaskets.
> 
> Bear


:agree Listen to the man!!!.....with mine clearanced tight and shroud half on the fan i CANNOT get my temp to push over 165 with a 165 Therm....


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## ottfive (Jul 23, 2012)

*Tires-Stance of 66 GTO*

Would appreciate photos of 66 GTO with 70 series tires on front and 60s series on back (please specify size of tires/wheels used) Thanks!


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