Grinding down impeller

drscott

drscott

Member
I purchased a new water pump and radiator for my 30 PU. There were instructions in with the new water pump saying if I have a new modern radiator that I would need to Grind off 1/3 from each fin.

They explain that the new radiator ( top ) could not handle as much water as the new water pump would pump in. I can certainly do this, I would just hate to grind too much / too little after spending this kind of money.

Any thoughts?
 
Run it and see what happens. You can always grind it down later if needed. Why do the work now if not needed. I have a recore with original tanks and no problems.
 
i would not grind it down at this point yet but would put a thermostat in the upper hose. a thermostat performs many benefits as keeping the engine at a better operating temperature. also when the t-stat is not fully open it will also restrict the flow and when it is open the body of the t-stat will cause some turbulence also and reduce the I.D. of the hose slightly. you can always grind it down later if you feel it needs to be and i like to use the fake water pump studs that can fool any fine point judge make it easier to r&i the pump.
 
I ran a rebuilt pump with ground down blades and had trouble with overheating. Replaced it with a sealed pump with full blades, no overheating.
 
Sounds like the instruction sheet is telling you the new core has fewer or smaller tubes and CAN'T flow the same volumn of coolant the original core can. I wouldn't be happy with that, and would rather have a Berg's recore.

As Mitch said, a thermostat is a wise move.
 
Once again, the pump outputing more than it can pull in theory. Maybe thats one of those water manufacturing pumps... Kind of like the old JC Whitney catalog. If you bought all of the gas saving items, you would save so much gas that you would have to drain out a gallon or two every time you drove the car.
 
For over 40 years, when rebuilding my water pumps, I have always drilled a 3/16" hole in each impeller and have never had a problem with overheating.

The water pump turns 1/4 faster than the engine RPM, if the water is entering the top of the radiator faster than the water can flow thru the tubes it will overflow into the overflow tube and the result is overheating from loss of water.

Be sure your radiator has the baffel in the top tank and the top of the overflow tube is bent to the back of the neck.

Ron
 
My two cars, when filled to the top will always throw water out when they are up to operating temp, until they reach their normal level which is just at the baffle.

Once there they stop throwing water, with no heating problems. for the next 500+ miles.
 
Snyders recommended grinding the tips of the impeller several years ago. I've been grinding a little less than 1/3 off the impeller tips of my model A water pumps with good results for probably over thirty years . I've never had a new old stock model A radiator but I suspect that any will overflow when hot or at high rpm, without some type mod. I figure that a thermostat would solve the problem because they have to greatly restrict the flow. On the other hand, when, not if the thermostat sticks in the closed position, it sure ain't going to help. I use the heavy duty eight fins per inch radiators on my best model A's and feel that they flow good. I have read that the first model A's had five blades on the impeller instead of three. Changeing to the three blade impeller helped but not enough. Ford must have known that there was still a problem. The change in water pump design in 1932 on the model B engines was a big improvement.
 
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I ground one down according to those directions and it worked OK. Later I bought a pump from James Rupert and he recommended not modifying the pump. It has worked fine for many miles. I have been told flathead V8's run cooler with high volume pumps. If it was mine I would leave it and use a thermostat as mentioned.

John
 
Eagle makes a good point,

The pump pulls water from the block and radiator core which theoretically have no air in them. If the pump cannot pull X amount through the radiator, its not going to pump more than that into the radiator, its impossible.

the only thing it may be able to do is pull air in through its seals or other leaks but that would just vent out of the radiator.

How is it possible to cause the radiator to overflow unless the bottom of the radiator and or block are filling with air during the process?
 
MrTube said:
Eagle makes a good point,

The pump pulls water from the block and radiator core which theoretically have no air in them. If the pump cannot pull X amount through the radiator, its not going to pump more than that into the radiator, its impossible.

the only thing it may be able to do is pull air in through its seals or other leaks but that would just vent out of the radiator.

How is it possible to cause the radiator to overflow unless the bottom of the radiator and or block are filling with air during the process?
Click to expand...

That's what I also thought until the rust flakes started leaving my block on my 28 and coming to rest on top of some of the radiator tubes (original radiator). That's when the problem started with the coolant filling the top tank and going out the overflow pipe. My 29 Tudor came to me with a 2 row aftermarket radiator, and it also filled the top tank and went out the overflow at the rate of about 1 to 2 quarts in 10 miles on the freeway.:mad:
 
Tom Wesenberg said:
That's what I also thought until the rust flakes started leaving my block on my 28 and coming to rest on top of some of the radiator tubes (original radiator). That's when the problem started with the coolant filling the top tank and going out the overflow pipe. My 29 Tudor came to me with a 2 row aftermarket radiator, and it also filled the top tank and went out the overflow at the rate of about 1 to 2 quarts in 10 miles on the freeway.:mad:
Click to expand...


Fair enough,

But what is actually going on? You can't stretch water and the system only has a certain amount in it. Perhaps a slight suction from the pump pulls dissolved gases out of the water but seems like it would need to be a lot.

Either air is some how getting into the bottom of the radiator and engine block, the water is expanding a lot due to heat, or its not happening and everyones lying. I doubt everyone is lying so it must be one of the other symptoms or a combination of them. Maybe churning of the water in the top of the radiator causes a lot of air bubbles to get sucked down. Wonder what happens if you overfill the radiator while its at its hottest point, would the issue go away?


Either way I don't like the thought of grinding the impeller down, how would you balance it?
 
Mr. Tube, I can't explain it especially since my water pump has never leaked and neither has my head gasket, so no air should get sucking into the system. Maybe CAVITATION has something to do with it. Just like my boat propellor being submerged in water, you'd think water would constantly have to be touching both sides of the blades, but at very high speeds you can get cavitation. That's where the water is pushed back faster than it's replaced, so you have a void on one side of the blades.
 
Tom,

You hit the nail on the head !!!!!

According to a elder A friend of mine who raced overhead engine A's, by reducing the amount of water pumped into the radiator not only reduces overflow but helps to stop cavitation (a void of air in the block when water leaves faster than can be returned thru the radiator).

Ron
 
About 7 or 8 years ago there were some water pumps on the market that had impellers that were too large to properly fit into the head cavity. That may have been the reason for instructions about grinding the impellers down.

We have a mature lady in our club who has owned her Model A since she was in high school. She drives it a lot, but is not capable of doing maintenance on it. For this reason she has to rely on help from other people.

About 7 or 8 years ago she needed a new water pump and paid a club member who was a mechanic to replace the pump. When he was finished she wanted to put anti-freeze in the radiator, but did not have any handy. A few days later she obtained the anti-freeze, poured it into the radiator, and started the car up. It let out with a tremendous squeal and smoke poured out from under the hood. She shut the engine down and backed away from it and was quite upset. She asked another club member and myself to look at it. What we found was that the impeller was too large for the head cavity and it was jammed inside the head. The squeal and the smoke was from the belt spinning on a jammed pump pully. One would have thought the mechanic would have given the fan a spin before he put the belt on. We had to grind the impeller down so that it would fit and spin free. We tried to take the same amount of material off each vane so as to not upset the balance. It has been working fine ever since.

Tom Endy
 
I run my Model A with the standard water pump. As the water heats and is pushed around by the pump, a surplus ends up on the upper tube sheet (upper box) of the radiator.

At first I lost a lot of water - and then I discovered the Ford Service Bulletin tip to bend the overflow pipe to the rear - overflow problem solved.

As to what replaces that water that all ends up in the upper waterbox, I imagine it must be air. Since water is being introduced at the centerpoint, then I imagine the air is moving to the outer edges, possibly even into the tubes and thus limiting some of the natural cooling surface.

Still, with the Ford recommendation (which seemed to have occured somewhat after the transition from "funnel top" radiator to the pipe radiator) the problem has pretty much gone away.

Well, maybe not completely. After refilling to the baffle, I might still tend to throw a little water for the first drive. As I come back, the cool level has dropped now somewhat below the baffle. But there it stays until I drain for the winter.

There is a little bit of the "Model T" thought in the Model A. If it's not nearly boiling, then it's probably not hot enough - and as long as the engine block stays covered, you're probably fine?

Your mileage may vary...

Joe K
 
MrTube and others: Remember the A's system is not a true closed system (IMO) and air can be sucked in thru the o/flow tube.
Regardless of whether air gets into the system or not, or whether the rad flows enough, I'll bet since 1928 AR's there have been thousands (probably hundreds of thousands, if not more) of Model A owners who have had their coolant blown to the wind. I'm sure it's not a "new" problem. JMO
Paul in CT
 
It is my theory that when the radiator restricts flow even slightly the water pump suction creates a low pressure condition in the block and cylinder head that promotes low temperature boiling (think of water boiling at high altitudes at less than 212 deg. ie. low atmospheric pressure)) at the cylinder head or other hot areas around the cylinders. The low temperature boiling can occur at 190 deg or so and increases the volume of the coolant, thus pushing it out the overflow. I have not tested this theory but someone suggested awile back putting a vacuum gage in place of the drain valve to measure the absolute pressure on the low pressure side of the system. Maybe this would clear up the mystery once and for all.

In 1937, I believe, Ford put the water pumps on the inlet to the block thus preventing the low pressure condition in the block and cylinder heads. This may have allowed them to reduce the size and cost of the radiators.
 
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