# cooling issue 66 gto



## Chris-Austria (Dec 23, 2010)

Hi!

What do you think about my idea:
I have problems with the cooling while driving at low speeds (with fan on temps go up to 210°) and when I drive faster (more than 30 mph) the temp goes back down to 190°.
I was told my fan is big enough, I should change my water pump and thermostat.

I found the flow kooler aluminium water pump at summit and a 160° high flow thermostat with a bypass hole. Do you think changing that will help me with my problem? It says the waterpump has double the flow rate at low speeds than stock and the thermostat will provide a better flow.

Until now I'm using the GM water pump (11 bolt) and a GM thermostat (180°). Radiator is big enough I think and the electric fan isn't that bad.

Because waterpump and thermostat are pretty old I think I should start with changing them instead of the fan, or is it a bad idea?
And will there be any typical problems by changing these parts? Will I need a new gasket for the timing cover? Because I can only find one with 8 holes, not the 11 holes like the water pump has.

Here is a picture of how it looks now:


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## freethinker (Nov 14, 2009)

the waterpump might help but i dont like that fan setup. 210 will not hurt the engine if it doesnt push water out. are you sure the temp gauge is right?


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## Eric Animal (Oct 28, 2007)

Chris, Your fan /shroud is only affecting the part of the fan it covers. You need to make the shroud large enough to pull cool air through the ENTIRE radiator....this is why temps fall with forward motion. The radiator becomes more effective because cool air is then passing through the entire core area. Eric:cheers


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## Chris-Austria (Dec 23, 2010)

How can I test the temp gauge? I think it works well, the infrared thermometer tells about the same temp when I point on the upper radiator hose. It doesn't push water out, even if I'm stuck in traffic and the temp goes up to nearly 220°.

@eric
That's what I thought.. it would be better if the shroud covers the whole radiator.. I found a fan with shroud that is exactly the same size than my radiator, but it is expensive! If the high flow water pump and thermostat don't change anything, I'll have to try the larger fan/shroud.. but I hope I can reduce the temp to a maximum of 200° in slow traffic. 

I can't build a shroud on my own, but if I find someone, do you think the fan itself is strong enought?


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## freethinker (Nov 14, 2009)

if it never overheats to the point that it pushes water out i would look for a better fan system and leave the rest alone. 210 is not hot enough to do damage as long as its full of water.


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## 66tempestGT (Nov 28, 2009)

it is all in the fan shroud. at low speeds you are only using part of your radiator.


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## Chris-Austria (Dec 23, 2010)

Okay, I've ordered the waterpump and the thermostat and I will change them, but I'll ask if someone can build me a bigger shroud if the problem will be the same.
Until now it never pushed out water, it's always full to the top in the radiator and a little bit in the overflow tank. Highest temp I've reached was 220° but it makes me nervous if it is such high, I don't want it to go higher than 200°.

This fan is exactly the same size as my radiator, but I don't want to spend $ 400... $ 300 the part and $ 100 shipping...


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## peahrens (Jun 7, 2010)

You might want to check out this thread that someone clue'd me to when a new 4-core (vs old 3-core) radiator and "new" rebuilt water pump actually increased my temp post warmup on my '66 389. The issues of incorrectly rebuilt 8-bolt pumps and divider plate clearances is a big aspect in problems in the 8-bolt systems. I'm awaiting the revamped Cardone 8-bolt rebuild part and hopeful that will make a big difference in my running temp.

Our Meeting With Cardone - The Over Heating "Fix" - PY Online Forums


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## pontiac (Mar 6, 2011)

220 temp is not a problem. don't go chasing ghosts. No boil-over, leave it alone.


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## Chris-Austria (Dec 23, 2010)

My engine isn't a '66.. it's a '69 428cui with a 11 bolt pump.. I hope the one I ordered will fit.. it's the 11 bolt flow kooler pontiac pump and looks the same if I compare the picture and the old pump. 

220 is near 230 and that's the point where it gets critical (thats what my mechanic told me..) This is why I want it to stay at 200.. if i get stuck in a traffic jam or drive on a mountain road I don't want the feeling that my car could overheat any time..


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## Eric Animal (Oct 28, 2007)

The Flow-Kooler should fit. I think the fan you have is big enough (looks) what is the CFM rating? The other fan will be quieter as it has curved blades...Look for a shroud to adapt to your current fan...see what a Tinsmith shop would charge to fabricate one for you.... Eric


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## 66tempestGT (Nov 28, 2009)

Chris-Austria said:


> Okay, I've ordered the waterpump and the thermostat and I will change them, but I'll ask if someone can build me a bigger shroud if the problem will be the same.
> Until now it never pushed out water, it's always full to the top in the radiator and a little bit in the overflow tank. Highest temp I've reached was 220° but it makes me nervous if it is such high, I don't want it to go higher than 200°.
> 
> This fan is exactly the same size as my radiator, but I don't want to spend $ 400... $ 300 the part and $ 100 shipping...


thats the one i have.








i dont have a pontiac engine but idling it goes to about 180 then kicks on runs for a couple of minutes till about 165 then cuts back off.


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## Chris-Austria (Dec 23, 2010)

@eric

I think the cfm rating is 2200, the bigger one has 3300.
I found out that there are 2 different pumps with 11 bolts.. one with 4" and one with 4,5"
I hope I have the 4,5" ( from gasket to hub end) because FlowKooler don't build the other one, which was only used on some early '69 models. I'll try to check that. Would it be very bad, if I use a 0,5" longer water pump? Will it work with the other pulleys and belt system??

@66tempestgt

Nice one, perfectly fits the radiator! Thats what I will do if the other modifications are not efficient enought. How loud is this fan?


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## Eric Animal (Oct 28, 2007)

CHANCES are that you have the 4.5 inch water pump,if not , you will have to purchase "early 69 pulleys" a PITA......I STILL think your problem is shroud related...or maybe a bad thermostat is you aren't observing much water flow....E You may be able to use a spacer to "build out the extra 1/2 inch"...going the other way is more of a problem.


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## 66tempestGT (Nov 28, 2009)

its not bad at all. if i sit in the car with the door open and my foot on the ground i can feel the hot air blowing on it. it moves a lot of air. i dont think i would mess with the water pump before at least getting a bigger shroud for the fan you have.


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## BearGFR (Aug 25, 2008)

Chris-Austria said:


> @eric
> 
> I think the cfm rating is 2200, the bigger one has 3300.
> I found out that there are 2 different pumps with 11 bolts.. one with 4" and one with 4,5"
> I hope I have the 4,5" ( from gasket to hub end) because FlowKooler don't build the other one, which was only used on some early '69 models. I'll try to check that. Would it be very bad, if I use a 0,5" longer water pump? Will it work with the other pulleys and belt system??


Howdy Chris,

I agree with what others have said about your fan shroud, that's likely to be the real problem.

I can speak to the 4" vs. 4.5" water pump question. My car originally had a 4" and I replaced it with a 4.5". It caused me some problems as I also had to swap the crank pulley "stack" and fabricate some spacers to move my alternator and power steering pump forward.

One thing you might try if you haven't spent money on parts yet, also if you do replace the water pump --- before you install it, "adjust" the clearance between the pump impeller and the metal divider plate. Lay the plate on the back of the pump WITHOUT a gasket and gently "work" the plate with a ball-pein or body hammer until it just -barely- touches the impeller. When you re-install it with the gasket in place, the clearance will be where it needs to be for best cooling.

Bear


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## injn37 (Nov 16, 2008)

Chris,
Now my two cents. Yes Eric A, I am alive!
I have a 455 and it runs real cool in hot weather. First question, why the electric fan? Even a big one flows much less than a mechanical. Cooling problem at stop or low speed is always a "not enough air flow problem" . If you can us a stock GTO shroud and a steel fan. 
Next, do check the diverter plate clearance. This is LIKE REAL IMPORTANT!!!!
Next, have a good radiator, and run a high flow 160 'stat. 

I run electric fans in my streetrods, and the mechanical fan outdoes them every time . And yes you need the 'full ' radiator area under that shroud!

Ok, back to nursing my sore jaw from the root canal. Where did I put down my Scotch!

rich:cheers


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## Eric Animal (Oct 28, 2007)

Rich, Glad to here you are still alive! Try some Jim Beam, and a Vicoden for that root canal......Eric:cheers:seeya:


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## injn37 (Nov 16, 2008)

McCallan Cask strength and codeine work pretty good!


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## Chris-Austria (Dec 23, 2010)

I've checked my old pump and I'm pretty sure it's the 4,5" one. But good to know, that there are some things I could do, if it is too long.

@bear
Thank you! Now I know what you mean with the clearence. There are 2 gaskets for the pump, so if the plate barley touches the impeller without the gasket, it will be as close as possbile without hitting the metal when I install it with gaskets. I'll tell my mechanic to do this, because I don't want to change the waterpump on my own and make some mistakes. 

Changing the thermostat isn't real fun but I did it last week with a GM 180° and there are no changes, but I'll install the 160° high flow one as soon as it arrives. 
Maybe I can find someone who can build me a better shroud, if it still runs hotter than 200° with the high flow pump and thermostat I'll do this or use the same fan with shroud than 66TempestGT.

Shipping for the mechanical fan and the shroud is very expensive, that's why I try the waterpump and thermostat first (they are pretty cheap, $170 all in all to Austria). And these are wear parts, sooner or later I'd have to buy them anyway and I don't have a clue, how good and old the ones are that I have in my engine now.


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## Chris-Austria (Dec 23, 2010)

I've changed the thermostat to a 160° F high flow and it makes a difference. (max temp 200° in slow traffic instead of 210-220°)
In 1-2 weeks I'll change the waterpump and if I'm lucky I don't need to change the shroud or fan.


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## Eric Animal (Oct 28, 2007)

Big difference! Good job....let us know what the waterpump does for it.:cheers Eric


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## Chris-Austria (Dec 23, 2010)

I've now changed the waterpump and the new one did fit just perfect! 
I can't see a big difference, but the temps don't reach the 200F any more. (not on the highway, not uphill, not in traffic)
While driving temps are at 170-180 and in traffic they go up to 190-195. I think the only way to drop the temps at low speed is a better fan shroud, but there is no need as long as temps stay below 200.

What do you think..
I think with the rad full of water the cooling isn't that good as with the rad only 3/4 full, is this possible?
Do you fill your radiators up to the top?


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