[Malky]

The picture of the stock-looking impeller with the vanes machined to a smaller diameter is interesting. That is the classic way of reducing the output of a pump. A pump manufacturer will tailor a pump to fit a customer's spec by cutting the vanes back like that. The flow varies directly as the outside diameter, the pressure as the square of the diameter and the power consumed as the cube of the diameter. So it looks like the rebuilder made a conscious decision to reduce the output of the pump from stock. I wonder why - perhaps they figured the OEM pump output was unnecessarily high, and they could cut back on power demand ... but why would they care, unless they were building it for racers? Scaling from photo, cut-back is about 20% of diameter, so flow would be down 20% and power required would be halved.
Malcolm

[soupman]

Malky, that is true. But in my case the additional height of the vanes made up for it. My original was 1/2" high vanes vs. 5/8" high vanes on the replacement one.

[ERIC17621]

Malky, that is an interesting observation. The only logical explanation I have is that with the taller pump vanes, it would seem like the sucking action of the pump drawing coolant out of the block will be improved. This appears to be the key to keeping our Pontiacs cool, rather then sheer volume of coolant flowed. We already know how critical a fraction of an inch is in pump efficiency, and how much a small adjustment to the pumps efficacy can improve cooling. With the taller, more efficient vanes, it appears that longer vanes are no longer needed. Perhaps a longer and taller vane will come into contact with part of the plate, and manufactures are forced to choose between longer, or taller, but not both. In either event, with the success everyone is reporting, apparently, taller vanes beat longer vanes every time.

[Edward Farrell]

AMAZING!!! There goes my cooling problem. Gimme that wrench!!

[rudytadow]

6t7gto or anyone else,
Question:
About to flush system. I bought a 12 oz bottle of Bar's leaks. It says to drain system, pour into radiator, refill with only water and replace cap. Run til operating temp is reached, turn on heater (I can't since I bypassed heater core) and run for 10 minutes. Then, when it cools down, flush system til it runs clear. Should I reconnect all my hoses and run the motor with hose in radiator to flush out? If so, should I pull the themostat during the flush out? Your thoughts would be appreciated. Also, my owners manual says 20.5 qts, (4 qrts = 1 gallon) so would 5 gallons 50/50 mix with distilled water be good enough?
Rudy

[Old Goat 67]

Rudy, I used a hookup in the heater hose, like the Prestone one's, and reverse flushed it for about 40 minutes with the engine running and thermostat out.
Charles

[rudytadow]

Old Goat,
How was your son's wedding?
Say, about the flush, I have all new hoses and don't want to cut into them (I know longer have the old ones) do you think what I wrote previously will work? Should I use the Bar's leaks 10 minute flush? Can I run the motor with just water for 20 minutes (10 min to operating temp and another 10 minutes for chemical to kick in)?
Rudy

[george kujanski]

I would like to know how does one "reverse flush' a running engine with the water pump running in the normal direction. One of those things that make you say Hmmmmmmmm...

George

[Old Goat 67]

OK George, that was a test to see if you were paying attention. You passed!

Yea, right..... Guess I have proved over again about the walking and chewing gum thing.

I promise to not try to work on the Goat and check the forum in the shop at the same time.

What I guess I meant was that I put the Prestone type hookup in the heater hose and reverse flushed it, and then ran the engine again with fresh water running in there also to finish cleaning out the flush real good. I put the flush in and ran the car to town and back to let it get good and hot and give it plenty of time to work. Probable about 45 minutes. Then flushed it out.
Rudy, I didn’t cut the hose, I just added a short length to one side of the adaptor and connected it temporarily. Took it out when finished. Back on the shelf again.
The wedding was OK, they sure are married now.
Charles

[george kujanski]

Didn't mean to get on anyone's case Charles, more of a comment on those "reverse flush kits" with the "T" that you install in the heater hose.If I recall correctly, the instructions say to run the engine while connected. I fact, when I was in my teens and working at a service station, they had a machine that hooked up & operated that way, or did they have the engine off while doing it? Don't remember....

George

[getmygoat]

Hi all,

I, like thousands of people, have been reading this post with great interest over the past few weeks...

I also have a GTO 400 that has overheating problems.. I've got this great test ride.. Head east out of San Diego up into the desert & mountains.. I'm usually up to 230 degrees about 20 minutes into the ride.. Not good.

Based on what I learned in this post, I replaced my stamped stell impeller with a cast version (the Cardone pump from parts america), coupled with an appropriate beating of the divider plate..

This weekend I went for another trip "up the hill" but unfortunatly, I havn't licked this issue yet.. i.e. temps were back up in the 220 range...

Based on more recent posts, sounds like perhaps I should switch to the carter or GMB pump?.. but my problem is especially sticky.. I am the lucky owner of an "early 69" GTO.. which was blessed with a unique water pump.. i.e. a "short neck" (11 bolt). (which is hard to find)..

I thus far have been unable to find a "short neck" version of the carter or GMB pumps..

Any suggestions?

Thanks a ton!

Fred

P.S. - I checked my timing and I'm running 9 degrees BDC w/ vacuum advance disconnected.

[grandville455]

Not sure where to get the pump ,but I think you should be running you vacuum advance tho?

[Old Goat 67]

George,
I didn't think you were getting on my case. I thought we were having a bit of fun. I rather enjoy arguing with myself, it's easier to win that way!
I just flushed both ways to hopefully get all the cleaner out as much as possible.

Fred,
Are you running without the vacuum advance hooked up? Or, just saying you checked it that way? I've never run that way voluntarily, but I remember having mine overheat when the advance unit quit working once. The 67 manual says, “Improper timing may cause overheating.” (Pg 6A-15)
My guess is that the engine is not at efficiency peak. Any thought’s here George, or anyone else?
What kind of thermostat do you have? You need a good high flow unit, not one of those cheapie things.
Charles

[george kujanski]

Fred what's the driving profile on your test trip? Low speed/high load or ? If lower speed, make sure you have a shroud to get max efficiency from your fan.

If the pump is moving the coolant, the answer lies in at least one of the usual suspects mentioned earlier in this thread. Start eliminating the easy ones first, etc. I would start by putting in a higher flow thermostat as OLDGOAT says; definitely operate with the vacuum advance connected.

George

[getmygoat]

Thanks,

I've got a hi-flow 160 degree thermostat on order from Summit.. I'll try that.

My driving profile going up the mountain is just 80 MPH straight out the highway.. (I've got a shroud already)....

Thanks again,
Fred

P.S. - Yes, I do run with the vacumm advance connected, I just disconnect it when I measure the timing. Sorry for the confusion.

[george kujanski]

Perhaps you have already checked it, but make sure the vac advance is working.

George

[Dirty70Bird]

Here is another success story. My car is a 1970 bird, 462 with about 9.5:1 CR, and a 160 thermostat. My car alwyas ran cool, even with the original factory 2 core radiator, around 180. I just bought an aluminium radiator because my factory 2 core started to leak. Anyway, since I had to drain the coolant to install the radiator anyway, I removed the pump for inspection. I have the cast blade pump, blades are about 5/8", and 8 blades total. Not sure on the diameter of the blades, but they looked like they are probably around the 4 inchers....I have about 0.055 inches of clearance between the divider plate and the top of the blades. Therefore I did not touch the divider plates. What about compression ratio? I do know that this effects the heating and cooling capabilities...Just a thought.

[428GTO70]

Ok, I finally got my new pump installed. When I removed my old one I thought it was the same as the new one and was kind of bummed. But when I removed the divider plate I saw the different length vanes and got happy again. Here is a pic of both pumps together showing the different vane lengths, but they are the same height.

[428GTO70]

Here is the original divider plate and pump as removed with about a .110 clearance.

[428GTO70]

And here is the new pump with the new divider plate after being hammered to about .045 spacing(with gasket). I will try to start it up tomorrow and post my results.