#41  
Old 06-16-2022, 10:23 AM
michaelfind michaelfind is offline
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For me, with exact same clutch, it was the belt. Just a little tighter on the belt and my squeal was gone. The clutch works well and should be silent. However, you will hear the fan roar when it is fully engaged.

  #42  
Old 06-16-2022, 10:43 AM
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lust4speed lust4speed is offline
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Definitely the belt. Also you will find that a Gates or NAPA equivalent belt will be much quieter that the cheaper belts that stretch like a rubber band.

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  #43  
Old 06-16-2022, 10:51 AM
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GT182 GT182 is offline
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Fullback, I had the same problem with my 66 4speed GTO. Car now has a built 400 instead of the 389. But I still have the 389 block for it. I was never a fan of an aluminum radiator but decided to give it a try. I bought a Cold Case thru Ames at the last PY show... probably 4 years ago. Best thing I did. No overheating now. Tho it will hit 195 once in a while depending how long you have to sit waiting for a redlight to change to green. Some here are a long wait. And that's using a 180 thermostat.

IF I recall correctly, the original factory thermostats back then were 192.

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  #44  
Old 06-16-2022, 11:33 AM
Brianbigoats Brianbigoats is offline
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On my freshly rebuilt 461 i am running 190 in traffic and 185 when i get it moving that is 90F weather

  #45  
Old 06-16-2022, 01:13 PM
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Fullback66 Fullback66 is offline
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Thanks guys.
Time to tighten up the belt. It does run cooler.
AWESOME!

  #46  
Old 06-22-2022, 02:23 PM
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Yesterday was the first real test for the new fan clutch. I am sorry to say that it FAILED.
It was a really hot day yesterday. The car still ran at 205 and 210 degrees. Same as before.
Could the clutch be bad? I do not hear it like some people describe.
I am disappointed in the results.
Maybe I need a new thermostat.
Any Ideas?

P.S. What is the belt size for fan and power steering?

Thanks
FB66

  #47  
Old 06-22-2022, 03:50 PM
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  #48  
Old 06-22-2022, 04:30 PM
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Take the thermostat out while you are working on the problem. My friends and I have probably tested over two dozen Pontiac engines and none of them ran hotter with the thermostat removed. There is enough restrictions in the engine and cooling system that the coolant cannot travel "too fast". In short, no thermostat and a perfectly working thermostat cool the same. There are other good reasons for running a thermostat but for testing you can't beat simply removing it and having one less variable.

You mentioned belt squeal earlier in the thread, and that would be a sign that the fan clutch is working properly. Use a good quality belt adjusted properly and you have removed another possible weak point from the testing process.

Use a known good temp gun to verify actual coolant temperature. For example, Stewart Warner guarantees their gauges to be accurate within 10° of reading. That means that an engine running an actual 190° can have the gauge read anywhere between 171° and 209° and it is within spec. Anyway, getting a second opinion might prove the gauge is very pessimistic. Now take a Chinese gauge and it can literally read anywhere.

Pontiac used a massive amount of different pulleys over the years, and for that matter even for a given model year. My '67 and my friends '66 used a 1/2" belt for the belt that went around the crank, water pump, and power steering, and a 7/16" belt that went around the crank, water pump, and alternator. In Gates terminology this would be an XL 25 belt that started with a 9 for the 1/2" belt and a 7 for the 7/16" belt. In my car's case, it took a Gates XL 25 9520 for power steering and a Gates XL 25 7490 for alternator. The different belt widths matched the pulleys with the wider groove in front. Not all years had the staggered widths.

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  #49  
Old 06-24-2022, 08:17 AM
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Thanks for the information. I will give a try. Maybe it is the gauge.
FB66

  #50  
Old 06-24-2022, 02:44 PM
Tarl Tarl is offline
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I have the Hayden SD clutch on my lemans and the HD on my firebird. The SD is much louder than the HD at most speeds, at least to me.

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