[PMDRACER]

Unfortunately it seems that you will have to go through a few boxes in the stock on hand at the parts house to find one. Some get lucky and get it the first ime.

[car guy]

Here are my results. No one in my area had remanufactured pumps on hand and I couldn't order one because there was no way to know which kind I would get. i did put on a new pump from Bosch that had cast impellers and adjusted the divider plate to about .08. I didnt notice any diffrence. As stated in my original post I would run about 210 degrees. I pulled the thermostat it was a 180 and tested it and found that it wasn't opening until about 200 degrees and I dont think it was opening all the way. I put in a 160 degree thermostat and after running about 10 minutes the temp. got up to 195 and held there running at 60 mph for 20 more minutes. stopping for stop signs it would jump quickly to 200 and go back down when driving again. When i got back home I let the car idle about 5 minutes and the temp got to 210. After shutting the car down the temp climed to about 220 degrees after setting 5 mins. I would like to have better but 195 at driving speeds and the temp outside about 75 degrees is not bad. What I would like to know is do you guys think these numbers are acceptable? I should add that after changing the thermostat i noticed a large increase in the coolant flow in the radiator and the car restarted better when hot.

[george kujanski]

temp rising at idle to me indicates lack of coolant flow (due to some other restriction) or a problem with airflow thru the radiator. Perhaps the inside of the radiator is clogged up slowing the heat transfer?

Since the temp drops when moving, either the increased airflow helps out or the RPM increase is giving you more coolant flow because of pump speed increase.

Sounds like your thermostat was restricting you tho. The easier restart also indicates your block temp is lower overall. Not bad. I think you should investigate the idle problem more closely, is it an airflow issue?

earlier you said that it started doing this all of a sudden, after storage. I'd say that may indicate clogging somewhere, or how about the vacuum advance? Is it still working or stuck?

george

[car guy]

Thanks George I will check these things out. I did have the radiator boiled out back in 99 and the antifreeze has been changed three times since. The car still has the original radiator which is a three row with a 4 blade fan since it is a non a/c car with four speed. I know I could change the fan and get a 4 row radiator but I do want to keep the car in it's original form. Is it possible that the radiator even after being cleaned has just seen better years and it is time for a new one?

[george kujanski]

A four blade fan? I checked my '67 manual and indeed, it says all but A/C cars had a 4 blade.

How about for test purposes get a 7 blade fan and maybe a shroud to see if airflow thru the radiator is the issue.

Hard to tell about your radiator; if you can see inside the filler neck and see crud stuck to the ends of the tubes, I'd say it may be time....

How about your heater core? if it is plugged, that will reduce the coolant flow thru the engine back to the pump.

George

[azbirds]

I would be looking for one of those nice 7 blade fans that Pontiac used in their later cars. My 69 T/A has one from the factory. I would say the temp your running at 75 is still not that good ( it would be a Stanley Steamer here in Phoenix) I agee with George, it sounds like an air flow issue. Are there any seals between the rad and core support? Fan shroud? What's the pulley size on the water pump? Some high output cars had bigger pulleys on the pump to slow it down for more power and putting a smaller pulley on may just give you that extra flow that you need at idle. Have Fun

[george kujanski]

Another thing I forgot: make sure your radiator cap is holding pressure. If not, the coolant will boil (turn to steam) and not circulate well and transfer heat poorly.

George

[car guy]

Problem solved! I checked vac.advnce and all was ok. I knew the cooling system was clean but i thought I would flush it anyway and as I suspected it was clean as a new car. However I did notice while it was idling that it seamed slower than it should so I hooked up my meter and it was 600 rpm that is the speed the manual calls for with the idle stop solenoid inactive. So I checked the solenoid and found that it had moved due to a loose bracket and this didn't let it make contact and increase the idle speed. Once I had that adjusted to the proper rpm of 1000 I had enough flow to create a whirlpool in the rad.

Anyway I drove it in 80 degree temp for close to an hour and combined it with in town and country driving. with 20 minutes of stop and go I was holding at 190 degrees and got to 195 while waiting for a train. In the country at 60 mph the temp stayed at 185.

I think I can live with these numbers. I had not driven the car much this year yet so I wasn't sure how bad the problem was going to be but had always heard that Pontiacs have heating problems and I just figured it was something I might have to live with. Thanks for the help.It was this post that got me checking things out and thinking that I don't have to accept higher temps.

[george kujanski]

In retrospec, it makes sense. The extra rpm of the pump and that dinky 4 blade fan is a 2-pronged improvement: more coolant flow and more radiator airflow. No magic, just science.

George

[skid2964]

This one looks good if the pic is accurate.

New Carter Water Pump

[428GTO70]

Actually thats one of the shorter vane designs as you can see the shiny ring around the edge where the vanes were machined shorter, the good ones have the vane all the way to the edge of the impellar disc. Or at least it was good for me, The one I removed was like that one in the picture and the longer vane pump helped my overheating problem big time.

[Old Goat 67]

I second 428 gto's opinion.
Charles

[getmygoat]

fyi everyone.. I went to Napa today looking for a pump for my '69 (short neck!)...They pulled out an "absolutely beautiful" (if there is such a thing) Pontiac 11 bolt waterpump.. Brand New, with a beautiful cast impellor, large vanes that went all the way out to the edge.. Gorgeous!

Napa carries several "lines" of pumps.. This pump was a NAPA branded pump, came in a big blue box with "NAPA" all over it.. The catalog the guy pulled it from also had a blue cover on it, and it was clearly for "NAPA" branded cooling parts.

Unfortunately, it was the long neck, so I'm still SOL.. but you guys with long neck pumps should be all set with this pump.. Its brand new, so there shouldn't be the variability in impeller designs that have been described... And that impeller is beefy! (It says right on the box "designed to OEM specs".... Maybe it actually is!)

Hope this helps,

Fred

[PMDRACER]

I'm running the pump with the shorter vanes that looks like someone machined the outer edge. Ity was an improvement over the stamped impellor, but I want more. Going to start looking for one with the longer vanes.

What did you pay for that pump at NAPA?

[getmygoat]

I didn't actually buy the pump, but its $45.. Part # is 55-975... That's the "long" pump, which is what most GTO's from 69-72 require.

I've got the rare "short" 69 pump.. I ordered the last one on the planet from NAPA in Denver today.. .It should show up in a week... Hopefully, it does, otherwise, I'm thinking of taking a long pump/good impeller to a machine shop and seeing if they can move the impeller to my short pump/bad impeller.

Fred

[jafuzz1]

Hello, I wanted to read all the replies to this lenghty post before replying myself. It's taken me awhile, but I wish I had seen this post earlier on in my engine temp lowering quests. I have a few questions. I had a NAPA reman pump in my '66 GTO, that I bought in '96 when I rebuilt the engine. I didn't start driving it 'till last summer when resto was done. She always ran 210-220 on very hot days, then boiled out when shutting it off. And that's with no tstat. This winter I bought a good used timing cover, and another pump from NAPA...this time it's a "new" not reman pump. It does have a cast impeller. I had it all back together when I read this post. So, I decided to pull the pump off, and sure enough, the vanes were at least .25 from the new Ames backing plate. I smashed the plate down to almost touching, and had to reform it so it sat flat around the outer perimeters as well. Now, back together, it runs 180-190 on hot days, and after some timing enhancements, it runs great, and only hits 210 after hot soak. I can live with that. However, it does not have a tstat in it. Should I be running one to slow the flow rate down, and give the rad time to cool the water? And, did the factory impellers that fit the plates correct, have a tapper from the outer edge of the impeller to the inner? I'm running a 15lb cap, is that what is right? Every thing is new...four core rad, 7 blade fan and clutch, stock 389 no ac, Cal emissions. Sorry long post...I still have more questions.

[PMDRACER]

Let me be the first to say welcome to the boards!
Everyone has a different opinion about whether to run a t-stat or not. IMHO if you live in a colder climate I'd tell you to definitely use one. Having the t-stat will allow the motor to warm up faster. I've tried not running one in all my motors and have never seen a difference for the better, but others have.
If using a t-stat just on just a restriction basis, Moroso sells 'restrictor discs'. In the kit are discs with different I.D.s and the idea is to swap out larger/smaller discs (in place of the t-stat) until you get what you want out of your cooling system.

[jafuzz1]

Thanks PMD...well, I'm in NW Ohio and only drive on good days...don't need to drive much in cold weather, and the summers here are like everyone else in the mid west...hot and humid. I just wondered if water flowing unrestriced would not disapate the heat at the rad if it was flowing too fast. My belief is, that once the engine temp is at the tstat rating, it is basicly free flowing, except the restriction of the tsat gizzards. I still think I have a temp problem at idle, because even at idle, it shouldn't climb as steady as it does. If putting in an open tstat will help out in the long run, maybe I'll try it. I'm gonna pull the plugs tonight and see what my fuel mixture looks like (haven't pulled a plug since the rebuild).

[george kujanski]

I'd say that the idea that the coolant moving more slowly thru the radiator to dump more heat has been debunked in this thread and other articles.

I like the idea of having a thermostat in the system because it will keep the engine temp in a narrower range, for which the mix and timing is calibrated (assuming the cooling system is working properly).

The best solution is probably using a high flow thermostat as mentioned earlier in this thread.

In your earlier post you did not mention that the temp climbs at idle. What exactly does it do?

George

[leecorrell]

Just thought I would post my results. My car has always had chronic temp problems even when it was still a 326. I have tried everything out there, so I thought I might as well try this. When I pulled my pump and found 1/2" of clearance I was sure this would do it. I have a stamped blade pump, and I have not been able to locate a cast style. Since my clearance was so excessive, I bent the blades of the pump as well as the plate to get it to about 1/16" of clearance. It was an anxious test drive, being almost sure this had been my problem all along, but no dice! It didn't even phase it - no difference, temp creeps up at idle. This is with a 2-core aluminum rad with the monster ford cooling fan. You guy's had my hopes up, and it was a fun little experiment, but I'll go back to just living with my hot Pontiac.