Question about pumps. I looked in my spare parts locker (GMC) and found a spare
water pump I keep for emergencies. It has 4" impeller blades. I have heard so
much talk about needing 4.25" blades. Is the one I have a good spare, or am I
in need of a different one. Any advise would be welcome
Al
>
> original. Right? >>
>
> Roger -- yeah, right!
>
> The clearance between the edge of the impeller and the chamber of the pump
> case is somewhat critical for the performance of the pump.__As a Chemical
> Engineer many years ago, one of my tasks was to design pumping systems. I
> don't have first hand knowledge of the design of automotive pumps but the
> basic principles are the same. If there is too much gap around the impeller,
> there will be "slippage" and the volume produced by the pump will suffer.
> The stamped out modern type impellers usually have quite a bit of gap but on
> the other hand they have a very smooth impeller surface. I suppose that the
> best would be to smooth and polish the larger diameter cast iron impeller.
> This should make a better pump, however to be realistic, is it really
> necessary to bother doing something like this? I hope that I'm not stepping
> on too many toes here, but I think some of the so called upgrades (not just
> water pumps) are being done just for the fun of it or is it "My toy is better
> than your toy!"?
>
> I would suggest to those with overheating problems to look first at other
> causes. Pumps sometimes go but it's failure would normally be a bad seal
> causing the shaft to leak coolant. The most likely cause of overheating is a
> buildup of material in the radiator core (clogging), a bad thermostat, a bad
> pressure cap, a collapsed radiator hose, or a loose fanbelt. The fan clutch
> does not cause overheating - it kicks in after the heat is already there in
> an effort to keep down the heat. Another thing overlooked by many is the use
> of a 50% antifreeze, 50% water solution. This results in a -34 deg. freeze
> protection which we really don't need, but it also results in a large
> increase in the boiling point of the antifreeze solution, which, coupled with
> a good working pressure cap, will raise the boiling point dramatically. Once
> the solution starts to boil your heat transfer goes practically to zero.
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM
water pump I keep for emergencies. It has 4" impeller blades. I have heard so
much talk about needing 4.25" blades. Is the one I have a good spare, or am I
in need of a different one. Any advise would be welcome
Al
>
> original. Right? >>
>
> Roger -- yeah, right!
>
> The clearance between the edge of the impeller and the chamber of the pump
> case is somewhat critical for the performance of the pump.__As a Chemical
> Engineer many years ago, one of my tasks was to design pumping systems. I
> don't have first hand knowledge of the design of automotive pumps but the
> basic principles are the same. If there is too much gap around the impeller,
> there will be "slippage" and the volume produced by the pump will suffer.
> The stamped out modern type impellers usually have quite a bit of gap but on
> the other hand they have a very smooth impeller surface. I suppose that the
> best would be to smooth and polish the larger diameter cast iron impeller.
> This should make a better pump, however to be realistic, is it really
> necessary to bother doing something like this? I hope that I'm not stepping
> on too many toes here, but I think some of the so called upgrades (not just
> water pumps) are being done just for the fun of it or is it "My toy is better
> than your toy!"?
>
> I would suggest to those with overheating problems to look first at other
> causes. Pumps sometimes go but it's failure would normally be a bad seal
> causing the shaft to leak coolant. The most likely cause of overheating is a
> buildup of material in the radiator core (clogging), a bad thermostat, a bad
> pressure cap, a collapsed radiator hose, or a loose fanbelt. The fan clutch
> does not cause overheating - it kicks in after the heat is already there in
> an effort to keep down the heat. Another thing overlooked by many is the use
> of a 50% antifreeze, 50% water solution. This results in a -34 deg. freeze
> protection which we really don't need, but it also results in a large
> increase in the boiling point of the antifreeze solution, which, coupled with
> a good working pressure cap, will raise the boiling point dramatically. Once
> the solution starts to boil your heat transfer goes practically to zero.
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM
