'67 GTO Overheating Problem Solved - Pontiac GTO Forum
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post #1 of 9 (permalink) Old 11-23-2014, 03:59 PM Thread Starter
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'67 GTO Overheating Problem Solved

Going down the mountain temp would drop to 140 but coming up by the time I got to the top it would be @245 and spitting out the overflow.
I thought it was the thermostat stuck open so I ordered a 195 high flow but the previous owner must have been a NASCAR fan because when I pulled off the housing there was no thermostat but in it's place an aluminum restrictor plate with a 1" hole in it.
WTF?
I just drove it down the mountain and up again and it stays right between 195-200 degrees.
Is this something that is made to replace the thermostat or someone's kludge?
It looks like it was made to fit and it is a pretty anodized red.

Edit: I found these online Water Outlet Restrictor Kits and it comes with 3 different size plates.

Last edited by Goat Roper; 11-23-2014 at 04:34 PM.
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post #2 of 9 (permalink) Old 11-24-2014, 11:20 AM
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Water outlet restrictors are for 'slowing down the water circulation so that the radiator has time to dissipate the heat'. They are supposed to be better than 'no thermostat'. I've always run a 160 'stat in all of mine, and have had no problems. I can't imagine not running a T stat in a street driven car. Cold blooded, contaminated oil, very short engine life....there is no up-side.
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post #3 of 9 (permalink) Old 11-24-2014, 12:38 PM
 
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The 195 thermostats are to speed up emission control systems to come on line or into closed loop quicker. Don't think i would go higher than 180 on these old dinosaurs. Your parts store should be able to get one.

Restrictors work well on engines with and electric water pump where flow remains steady, not effected by rpm's. Circle track cars run in a high but narrow rpm range. So a restrictor tuned for the application may fit the bill.
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post #4 of 9 (permalink) Old 11-24-2014, 03:23 PM
 
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I use a 160* t-stat also. the motor actually stays in the neighborhood of 180*, on a hot day alittle higher.
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post #5 of 9 (permalink) Old 11-24-2014, 03:43 PM Thread Starter
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Originally Posted by rickm View Post
I use a 160* t-stat also. the motor actually stays in the neighborhood of 180*, on a hot day alittle higher.
This car runs hot it came with a 6 1/4" pulley part # 9788886 XT but I cannot find this pulley anywhere so I went with an 8".
Then it started to boil over so I chucked the bent pulley up on my bench grinder and bent it back with a deadblow hammer.
it is still a little bent but a lot better than it was.
I don't think I will be able to find this pulley and nobody remakes it and I have a couple parts guys trying to source one.
I do know a local guy with a CNC machine so I may just take in the 8" and tell him to make me one the same only 6 1/4" diam.
I am going to take it down the mountain for an alignment this week and see what the temp does running it up the mountain.
It has a new radiator so if it boils over the next step I guess is a high volume pump and a 180 stat.

So far it is working but the temp outside was 38 when I tested it, it will be a different story in the summer when temps hit triple digits.

The radiator has a shroud and the fan is a little less than an inch from the radiator.
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post #6 of 9 (permalink) Old 11-25-2014, 06:10 AM
 
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there are a lot of issues that make a Pontiac engine run hot. lots of threads about it. you have to address each one, one at a time using the process of elimination to find why its running hot. ames sells pulleys, but they make you buy a matching set for your engine. don't think they sell them individually.
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post #7 of 9 (permalink) Old 11-25-2014, 11:46 AM Thread Starter
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there are a lot of issues that make a Pontiac engine run hot. lots of threads about it. you have to address each one, one at a time using the process of elimination to find why its running hot. ames sells pulleys, but they make you buy a matching set for your engine. don't think they sell them individually.
I want to keep it original and I had to go old skool to find the the pulley and get on the phone and found one yesterday in Minnesota.

I will install it when it gets here but not a lot I can do until spring since it is 39 degrees right now so it isn't overheating even when I run it hard uphill.
I will pull the pump and do that fix next summer and go with a 180 tstat if it is still overheating.
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post #8 of 9 (permalink) Old 11-26-2014, 08:51 AM
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Garage
#1 cause of Pontiacs running hot is improper clearance between the pump impeller and the divider plate behind it. If this clearance isn't right (too wide) then nothing else you try is going to help. There should be quite a few posts on here talking about how to do it that ought to pop up in a search.

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post #9 of 9 (permalink) Old 11-27-2014, 10:37 AM Thread Starter
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Well I couldn't get it to overheat running it hard up the mountain, the good news is I didn't get a ticket the bad news is the heater core puked on the floor.
I guess putting in a tstat blew out the pepper.
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