[HaroldL]

Fixed my water pump plate, Pontiac runs much cooler due to greater pump suction.

One question, how do I explain to my wife about the concept of proper pump suction ? She has a lot of questions about cars, but this is one area I think she need to understand, deeply.

[jal]

Well,
I figured I would chime in here with my results.
I just looked at this post about a week ago and saw that many people were having the same issue with cooling as me. I followed all the posts fairly closely and decided to pull my water pump this past Friday.
I found that the one on the motor was a stamped steel type. I found the Cardone at my local AutoZone for a whopping $12.99!!!
It was as pictured with the cast impeller.
Without the gasket the new pump measured about 0.060", with the gasket about 0.100". I took the advice and took my time bringing the divider plate to about 0.055" with the gasket.

The results are pretty amazing. I figure I gained about 15 degrees with this change.

Thanks....

[72LemansFreak]

Great info, everyone! Now I did spend the better part of Friday reading all the posts, but I didn't find a good (for my addled brain) explanation of how to "massage" the water pump plate to reduce the clearance to the impeller. I understand that people have been using a hammer and a block of wood, but would anyone care to go into more detail. Thanks! This forum rocks!

[jal]

HenryK,
I did exactly what you stated.
I took the divider plate, placed onto my garage floor (concrete), and used a very normal claw hammer. It's not a heavy hammer.
I lightly tapped all the way around the perimeter of the divider plate in a normal circular motion where it's specified on page 1 of this post. I would only go around 1-2 times before placing back onto the water pump and measuring with a feeler gauge. This only took me about 5-10 minutes to accomplish the desired result. 0.055" clearance with the gasket.

Hope that helps,

joe

[Amlsml]

did you use permatex between the divider plate and each gasket?? would that hurt my application?? my car is ripping hot with a 4 core and a new cast impeller /

[george kujanski]

Keep in mind that on a 8 bolt pump, the actual "divider plate" is just placed into the pump cavity.

The 11 bolt pump does not use a "divider" plate like the 8 bolt types do. The 11 bolts just have a plate similar to, but different shape, than the "internal housing" on the 8 bolts.

george

[poncho1961]

gtojoe228, yes, if the plate brazed on your pump is flat, closing the gap would help with the efficiency. if the plate has a small nose that pilots through the spacer plate, look for clearance around the o.d. of this nose. again, you would want a small (.015 +-) gap for best efficiency. to answer some other posts about impeller length, it is a common practice in the pump industry to "trim" an impellers diameter to achieve different flow and pressure rates from any given centrifugal pump. It may be that the manufacturer of the impeller with the large vane to plate gap increased the length of the vanes to crutch their lack of flow due to efficiency. As a side note for those of you running a regular water pump on your strip cars, longer vanes produce more flow and therefore require more horsepower to operate. on the street i think you would prefer to flow and sacrifice a little HP to keep your cool, oh, and your cars too. Don't worry George, I'm not looking to cut into your $. By the way MR68, I've noticed most of the Pontiac pumps are painted blue, almost an Aurora Pump blue, far from that B & G red your used to seeing. Rick

20 years as service manager, General Pump & Machinery, Kidding aside, I work on anybodys brand pump, they are all pretty decently made anymore, design wise, lots of the B & G red in my area.

[GTOJOE228]

Rick, Based on what you're saying I should close the gap to the desired .015 now what happens to that suction effect? The disc is closed and has no hole in the middle. Joe

[poncho1961]

GTOJOE228 I would like to see a photo of the impeller if you could. To my knowledge, I have never seen an enclosed impeller without a hole in the front. There needs to be an inlet to the vanes of the impeller. Water enters at the center and centrifugal force throws it off at the O.D. No water to center eye of impeller equals no water coming out of impeller. In the industrial pump world, there is a pump manufactured that uses nothing but flat discs in place of the impeller, no vanes, but the media being moved is usually a slurry and not just water. I suppose it would flow a LITTLE water just from the churning motion of the impeller, but not nearly enough to cool your auto. If in fact there is no hole in the center of your plate, and there are vanes under that plate, I am figuring it was a monday or friday job and somebody screwed it up.If you were mistaken about the hole and it is there, yes, shoot for the .015 from the plate. I,m sorry my reply took awhile to post. I thought it was a good idea to look at the previous 36 pages. What was I thinking?LOL Don't ask me what pages, but there are at least two pictures posted that show the impellers with plates on the front, both have holes in the center. One was welded and the other riveted on. As MR68 stated I believe or maybe Malky, sorry after 37 pages I can't even remember who I am, the enclosed impeller will be more efficient but it should still have as small a gap as possible between the divider and impeller so as to limit recirculation within the pump. BTW, I must say that I'm pretty proud of this complete 37 pages. Experience with some of the other long threads on this site show that some result in name calling and stray way off the original post. Great job keeping this one on track for 2 years and how many thousand hits.

[poncho1961]

BTW for those interested, I started reading page 1 around 8:15 this morning and stopping to do some work I actually get paid to do, I finished page 37 around 1:00 P.M. Guess I'll take a lunch break, reading makes me hungry.

[Verdero Green]

Thanks for all the information from the folks that posted. I have a 455 that runs warm too on 85 degree days it runs 190 and up and forget about driving around town and sitting there idling. I have the pump off and it is a milodon aluminum I got from summit and I also have a new iron pump with a cast impeller. The aluminum pump does have a little deeper vanes on the impeller. They both have excessive clearance to the divider plate. Which one would should I adjust it for and use? The milodon pump does not have a shield on it over the vanes. Thanks for your input and I'll post the results. I do have a new 4 core radiator in the car with the factory shroud. It is a 70 4 speed car. Thanks again.

[george kujanski]

I'd use the one with greater vane area, it'll move more coolant.

Adjust the plate for minimum clearance and you'll be good to go.

George

[RevGTO]

Ok ... here's my cast impeller story. My 69 GTO has always run warmer than it should - .030 over 428, 6X-4 heads, q-jet. Idling in traffic with A/C on a 95* day would mean 220* and climbing. And that's with a new Desert Cooler, quality fan clutch, 70/30 water/coolant w/Waterwetter, adjusted timing, etc. Nerve racking to say the least. Finally pulled the pump (correct #97993651), and sure enough, stamped impeller with a huge clearance at the divider. This is the standard short hub 69 pump; I checked everywhere but I could not find one with a cast impeller. Finally, I found a 70 pulley so I hammered down the divider and installed a later style pump I had with cast impeller. Results? Idling in traffic with A/C on a 100* day it did not get over 200*. But: I also noticed that the car tends to get progressively warmer while cruising and then cool down a bit when I slow down or come to a stop. So far, nothing above 200*. Is the water moving too quickly throught the radiator now at cruise? Anyway, that's the story so far and another day, another dollar for George.

[Verdero Green]

Just wanted to report my results. Yesterday I finished installing a standard cast impeller water pump with as little clearance as I could get on the divider plate. I also tried the thermostat hole drilling idea from someone else here. I drilled 8 holes in it. Temp outside was about a 100 degress and high humidity. It ran about 200 the whole time on the highway and more idling around town. I put the aluminum milodon pump back on today and at 90 degree temp it ran about 185 on the highway and 200 around town. I did stop in front of the shop and let it just idle for five minutes and the temp rose to just over 230. If anyone has more suggestions I am wide open. I think I am going to go back and try the other thermostat and see what that does. It is also a 160 degree thermostat but it is a different design. I think it is a milodon I got from summit. Thanks for your help and all the information in this post.

[66GTO Jim]

Okay George, another Dollar is headed to the Grand Cayman Islands for the "George's Retirement and GTO Fund" and worth every penny and more! After I stroked my 389, it was running up to 220 degrees in traffic on an 80 degree day. That was with a 180 Thermostat, 4 row radiator, correct shroud etc... and a GTO that had never ran hot before the engine rebuild. Of course I put a new 8 bolt water pump on during the rebuild. lol I applied your fix awhile ago but was waiting for some real Hotlanta weather here in Georgia for the acid test. Last Saturday went on a day cruise with some other musclecars. Over an hour at 60+ MPH on hot blacktop roads, 94 degrees outside and my car ran mostly at 185 degrees! Then into traffic and stoplights and it never got above 189 degrees and it mostly stayed at 185! Stopping for gas, it ran up over 200 while shut off (mechanical gauge). Within a few minutes of "in traffic" driving, it was back down to 185!

Forgot to add, gap was .120" and was reduced to .045".

Out of all the tips I have read and tried on this and other forums, this is definitely the best! Thanks George! Wonder what the score is now, comparing those this fix worked for and those that it didn't... Thanks again! Jim

[george kujanski]

Glad to hear more Ponchos are cooling off. I'll have to go back someday and do a recalc.

I still wonder why some members still have probs; some at higher speeds, some at idle, even with good equipment, fans, pumps, radiators..

George

[Mr_GTO]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by george kujanski:
Glad to hear more Ponchos are cooling off. I'll have to go back someday and do a recalc.

I still wonder why some members still have probs; some at higher speeds, some at idle, even with good equipment, fans, pumps, radiators..

George </div></BLOCKQUOTE>

Not everyone's engines are the same. Some are bored differently, some are assembled more loose or tighter, some use better oil, some have better gauges...it could be a thousand different things...

[GTOJOE228]

Does anyone feel that by switching over to synthetic oil would shave a few degrees off of the guage?

[66GTO Jim]

Pontiac engines have for years carried the reputation of usually running hot after they are rebuilt. This was long before Rodney Reds, good aftermarket electric water pumps and electric fans were available for Pontiacs.I was just thinking about all the reasons I have heard over the last forty years about why Pontiacs run hot after being rebuilt. Such as cylinder wall castings too thin when bored out, bare block not being cleaned out thoroughly, cylinder placement etc etc. Looking back now, I wonder how many of these problems were actually caused by this gap being too wide when replacing the water pump when doing the rebuild. Interesting... Jim

[PMDRACER]

In case anybody needs the info, (I'm sure it's been said before but what the heck), I had to get a water pump for the '69 today. Walked in to the Kragen around the corner. They carry Cardone Select water pumps, 100% new, including the main body and a cast impeller for $31.99.