Do you grind your water pump impeller blades?

28 Special Coupe

28 Special Coupe

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I purchased a new leakless water pump from Snyder's and the instructions that came with it say that reproduction radiators cannot handle the same flow rate that originals did and therefore you have to remove about 1/3 of each impeller blade so that you don't pump coolant out of the overflow. Have you guys found this to be a problem?

I have a Brassworks 10 fin-per-inch radiator, but I'm also running a 160 degree thermostat. Will that slow the water down enough or do I still need to grind the impeller? To grind, or not to grind, that is the question!

Thanks for your help, guys.

Steve
 
Steve,

I have a different method that I have used for the last 40 years on rebuilt water pumps : I drill a 3/16" hole in each impeller. Currently have a heavy duty, 10 fin to the inch, in my 30 Coupe, no thermostat; same method on my early 28 with original radiator, and 29 Roadster with standard radiator.

Ron
 
I would leave the impeller blades alone as long as your test fitting of it to the head with studs in place for alignment (or cap screws) indicates that it is clear.

I had to take about one half of an RCH off of a new pump impeller for it to fit in a new Brumfield head; took a second with a die grinder.

In my opinion, the advice to take a 1/3 off in order not to overwhelm a radiator is pure bunk, unless the radiator is severely clogged already. Come to think of it, about a third of radiators out there seem to be severely clogged already so it may be good advice (for the vendors).:D
 
I put a new leakless from Brattons on my stock '28 this spring, and am running a brassworks HD 10 FPI radiator.

I saw nothing in the instructions about "removing one-third of each impeller wing to prevent over-pumping".

There was an instruction to fit the pump up to the head w/o a gasket, and rotate the impeller to check for binding, and if any, to carefully grind some stock off the rear edge of each impeller wing; I did have to do this; only took a couple light passes and two "fittings".

It has all worked fine. I ran w/o a stat all summer, with no particular overflow issues.

I installed a 160* stat about a month ago; still no issues, and now the water temp is up to 160-170 within 5 minutes running.
 
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"the instructions that came with it say that reproduction radiators cannot handle the same flow rate that originals did"

The buzz word is "reproduction radiators".

I had that overflow situation because the surge tube below the fill hole had rusted away. I flattened an aluminum beer can, rolled it into a tube, shoved it down the fill hole so the overflow was inside of it and drove the old '31 pickup for the rest of its life without water loss through the overflow. That was 1960s road engineering. I just checked my 1930 Tudor and noticed it did not have a surge tube in it. Guess it's time to drink another beer.

Refer to Model A Ford Mechanics Handbook, Vol I, by Les Andrews page 1-235, "Overflow Tube and Baffle".
 
Thanks for you responses. I think I'm going to grind the impellers only if there's binding, like Frank did. Since I replaced my water pump studs with bolts and because I have a 2 blade fan, it's not too difficult to remove the pump and grind some more if I experience any trouble. I doubt that I will, though.
 
I second the impellers being too big. The 1st reproduction shaft with impeller was put together incorrectly with the impellers pushed to far forward, leaving the back end of the shaft too long. When I tightened my water pump down, the pump housing broke.

Told Bratons and they sent another that was correct in impeller placement, but the impellers were too large, catching on the inside of the head. Ground them down a little bit for clearance only, and it worked fine.
 
The problem being corrected by grinding the impeller blades off a bit is not too much water flow for the radiator to handle. Any water coming out the pump has to come from the outlet of the radiator (bottom). It can't overflow at the top when all of the wate ris coming out of the radiator to begin with.

The large impeller blades create such a strong suction inside the waterpump that it sucks in air at the waterpump shaft. When you introduce air at this point, it pushes the water level up at the upper tank, and the water flows out the overflow.

Grinding down the blades reduces the suction at the impeller shaft and reduces the amount of air sucked in at the shaft, especially at high RPM.

So the "solution" of grinding the blades fixes the problem for a reason other than the one you think.
 
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