Digital Corpus
Top Post Dawg
For those who are around, it is known that a couple of good brands for water pumps are Graf and Geba. I'm sure there are some additional [re]brands that are equal in quality and I'd like y'all to comment to that effect.
The point of making this thread is also to call to attention the 3 different types of impellers used in [our] water pumps and to list known variations amongst brands. I know that this is a *really* late-to-the-party topic for our generation of TDI, but this information is still relevant. I'm putting this here instead of in 101 because I'll be listing specific part numbers for the B4 generation.
Types
The first type of impeller which is used by Graf and Geba (usually listed in the title) is a stamped, metal impeller like what is shown below:
The next type of impeller is centrifugal, which isn't dissimilar to a turbocharger impeller:
And then there is the third variation, a plastic centrifugal impeller:
Why the distinction?
Well this comes down to performance as well as longevity. The stamped style impellers, whether for our cars or not, are an inexpensive, stock level pump. It'll perform well for all of the normal daily driver needs. Even though the pumps can fail, they can fail in different ways and there is one mode of failure specific to a stamped impeller. One of the fins can break off and then wedge itself in the coolant path. I know of this happening and needing to be fixed by one of our gurus, Matt Phalen. Just keep in mind, just because it can happen, it doesn't mean that it will.
Now the next two pumps differ by function of longevity. Centrifugal impellers are better for higher flow. Because there is a gradual vector change of the coolant, not just a 90° blade saying "go this way now" you have a significantly lower likelihood of cavitation. Cavitation occurs when the absolute speed of the fin relative to the properties of the fluid is so fast that a vacuum bubble occurs on the surface of the fin. This bubble is not constant and in the midst of turbulence of the fluid it will collapse back onto the find causing localised heat and rapid erosion. Centrifugal impellers have a significantly reduced chance of this occurring because of their design. With that said, we have plastic and metal varieties of these pumps. They tend to be able to flow more fluid across their operating range.
The plastic versions of the impellers though, due to thermal cycling are known to come loose off of the shaft of the pump. This, from what I recall and I welcome clarification from others, typically occurs when the pumps are used past normal intervals of ~120K miles.
Pro v Con
Stamped metal:
Metal Centrifugal:
Plastic Centrifugal:
So who makes what?
Well, keep in mind that the impeller doesn't mean everything. The quality of the construction and seals have a major impact on the life of the pump. Known good brands have a better track record that others, but manufacturing tolerances and factors that boil down to pure chance can happen. Also, value of a purchased can be altered by the inclusion or exclusion of ancillary components like gaskets. With that said, here are some brands and/or part numbers of each of the variations. Use your head and don't treat these as endorsements.
Stamped Metal:
Geba from IDParts
Graf from GAP
Graf from FCPEuro
GMB from Amazon
Metal Centrifugal:
ACDelco 252-662 from Amazon
DuraGo 54801010 from Amazon
Cardone 57-1267 New/Reman from Amazon
Cardone 57-1267 New/Reman from Amazon
Meyle from FCPEuro
Plastic Centrifugal:
Geba W01331625251GEB from Amazon
US Motor Works US9065 from Amazon
Cardone 55-83116 from Amazon
Final personal note, I do want to say that the ACDelco pump include 3 studs which are for the pulley and includes a metal gasket. I'm not due to change my pump out right now, but due to moving over to a higher temp thermostat, and higher performance expectation of the motor, I'll be using this style of pump for a while. Specifically, I'll use this one unless it fails early and often.
The point of making this thread is also to call to attention the 3 different types of impellers used in [our] water pumps and to list known variations amongst brands. I know that this is a *really* late-to-the-party topic for our generation of TDI, but this information is still relevant. I'm putting this here instead of in 101 because I'll be listing specific part numbers for the B4 generation.
Types
The first type of impeller which is used by Graf and Geba (usually listed in the title) is a stamped, metal impeller like what is shown below:
The next type of impeller is centrifugal, which isn't dissimilar to a turbocharger impeller:
And then there is the third variation, a plastic centrifugal impeller:
Why the distinction?
Well this comes down to performance as well as longevity. The stamped style impellers, whether for our cars or not, are an inexpensive, stock level pump. It'll perform well for all of the normal daily driver needs. Even though the pumps can fail, they can fail in different ways and there is one mode of failure specific to a stamped impeller. One of the fins can break off and then wedge itself in the coolant path. I know of this happening and needing to be fixed by one of our gurus, Matt Phalen. Just keep in mind, just because it can happen, it doesn't mean that it will.
Now the next two pumps differ by function of longevity. Centrifugal impellers are better for higher flow. Because there is a gradual vector change of the coolant, not just a 90° blade saying "go this way now" you have a significantly lower likelihood of cavitation. Cavitation occurs when the absolute speed of the fin relative to the properties of the fluid is so fast that a vacuum bubble occurs on the surface of the fin. This bubble is not constant and in the midst of turbulence of the fluid it will collapse back onto the find causing localised heat and rapid erosion. Centrifugal impellers have a significantly reduced chance of this occurring because of their design. With that said, we have plastic and metal varieties of these pumps. They tend to be able to flow more fluid across their operating range.
The plastic versions of the impellers though, due to thermal cycling are known to come loose off of the shaft of the pump. This, from what I recall and I welcome clarification from others, typically occurs when the pumps are used past normal intervals of ~120K miles.
Pro v Con
Stamped metal:
- Stamping is a less expensive manufacturing method
- Failure modes not common during normal daily driver use
- Commonplace, easy to find style of pump
- Two failure modes, one of which can block a coolant passage
- Erosion via cavitation can require the pump housing to be replaced
Metal Centrifugal:
- Casting and subsequent machining of the impeller are more expensive manufacturing costs
- Extremely unlikely to fail with a broken fin
- Not prone to cavitation and thus can be used for higher RPM driving
- Less common style is more difficult to find and can be confused for a stamped metal impeller based on imprecise descriptions.
Plastic Centrifugal:
- Plastic composite is easier to cast and machine than metal, thus is less expensive than metal variation
- Also shares same lack of cavitation characteristics
- Also shares improved flow characteristics
- More common/unique failure mode of impeller separating from shaft
So who makes what?
Well, keep in mind that the impeller doesn't mean everything. The quality of the construction and seals have a major impact on the life of the pump. Known good brands have a better track record that others, but manufacturing tolerances and factors that boil down to pure chance can happen. Also, value of a purchased can be altered by the inclusion or exclusion of ancillary components like gaskets. With that said, here are some brands and/or part numbers of each of the variations. Use your head and don't treat these as endorsements.
Stamped Metal:
Geba from IDParts
Graf from GAP
Graf from FCPEuro
GMB from Amazon
Metal Centrifugal:
ACDelco 252-662 from Amazon
DuraGo 54801010 from Amazon
Cardone 57-1267 New/Reman from Amazon
Cardone 57-1267 New/Reman from Amazon
Meyle from FCPEuro
Plastic Centrifugal:
Geba W01331625251GEB from Amazon
US Motor Works US9065 from Amazon
Cardone 55-83116 from Amazon
Final personal note, I do want to say that the ACDelco pump include 3 studs which are for the pulley and includes a metal gasket. I'm not due to change my pump out right now, but due to moving over to a higher temp thermostat, and higher performance expectation of the motor, I'll be using this style of pump for a while. Specifically, I'll use this one unless it fails early and often.
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