So .. in my searches for a water pump i basically found them available in two materials, plastic and cast metal.
However i did find one brand offering welded steel! and at a very affordable price.

Acknowledging the fact that impeller material doesn't necessarily reflect on the quality of the water pump as a whole since there are other factors to consider.
Lets discuss what are the advantages and drawbacks of these materials in themselves, for use in a water pump.


It would seem like to me, that the welded steel impeller would cause more cavitation which would result in more aeration and thus more corrosion and worse cooling. but that's just my observation.
What do you think?

 

The welded impeller also has more area to move coolant, as compared to the other two examples, so, one would think it would be a more 'efficient' pump. Not that that is really important...... Any of the three would move enough coolant to do the job. I wonder if the welded feller would make the heater work better.

 

hard to know how good a part is by looking at it. When i'm not sure and I want a good part...I spend the extra money and by the oem part. In my 14 years in the trade...they usually fit better, install easier and must meet oem build requirements.

I have worked at dealerships and aftermarket. Canadian tire's cheap part line were the lowest quality parts I have ever seen.

 

There are definitely larger passage ways on the welded impeller due to the thinner walls of the impeller, but it looks like the blades are straight lacking a involuted curve on the impeller blade which might actually cause cavitation. However a curved welded steel impeller blade would be easily possible. maybe they are trying to cut manufacturing costs?

The welded steel and the cast impellers would "seemingly" transfer more heat more efficiently to the shaft than the plastic impeller, which might be a good thing if the vehicle had a fan clutch

 

Very true. Most after market "affordable" pumps skimp on bearing / seal quality

 

That OEM will probably last you the life of the truck.

A Murray WP with plastic impeller lasted for over 82K before it went bad on my truck. The plastic impeller looked flawless, but the bearings were shot and it was very hard to turn the pulley when I pulled it off. It didn't leak either. I bought a new pump (GMB) with metal impeller, cause I figured it was time. The old pump started chirping a few days after it arrived. Talk about perfect timing!

 

QUOTE=Dodgevity;3431229]That OEM will probably last you the life of the truck.

A Murray WP with plastic impeller lasted for over 82K before it went bad on my truck. The plastic impeller looked flawless, but the bearings were shot and it was very hard to turn the pulley when I pulled it off. It didn't leak either. I bought a new pump (GMB) with metal impeller, cause I figured it was time. The old pump started chirping a few days after it arrived. Talk about perfect timing![/QUOTE]

I actually was considering the Murray but i broke the bank and went with a Mopar.
However i am somewhat disappointed in the Mopar impeller.
it seems to be made of two pieces of fiber plastic glued together and not even aligned very well.


I am still at a loss to explain how the coolant in the old pump, made it past the main seal into the weep chamber then through the rear bearing seal and out the front bearing seal and the weep hole be dry as a bone. i may take the old pump apart just to solve that mystery.

 

I actually was considering the Murray but i broke the bank and went with a Mopar.
However i am somewhat disappointed in the Mopar impeller.
it seems to be made of two pieces of fiber plastic glued together and not even aligned very well.


I am still at a loss to explain how the coolant in the old pump, made it past the main seal into the weep chamber then through the rear bearing seal and out the front bearing seal and the weep hole be dry as a bone. i may take the old pump apart just to solve that mystery. [/QUOTE]

That area on one of my Gravely tractor water pumps was full of grease. 40 year old grease.... it sealed the weep hole rather well.

 

Humm... wonder if i should put a grease fitting in the weep hole....

 

I actually was considering the Murray but i broke the bank and went with a Mopar.
However i am somewhat disappointed in the Mopar impeller.
it seems to be made of two pieces of fiber plastic glued together and not even aligned very well.


I am still at a loss to explain how the coolant in the old pump, made it past the main seal into the weep chamber then through the rear bearing seal and out the front bearing seal and the weep hole be dry as a bone. i may take the old pump apart just to solve that mystery. [/QUOTE]

That even looks cheap....... I got AC Delco part not too long ago that was china and FOMOCO (FORD) that was from Phillipeens; I got mopar that was from Malaysia. So they have gotten cheap with OEM parts unless its one of the good manufactures from Federal or Wix or stuff like that name brand. Its starting to get really hard to justify factory OEM when its becoming the same cheap crap as aftermarket.