Depending on year/model, VW lists different thickness of gasket for that
type of pump. Either .75mm or later 1.5mm. Many of the later ones I see
with that composite impeller come with a thick metal gasket that has
raised rubber sealing surfaces. Looking at the gobs of RTV someone used
on that one in your photo I'd worry about other shortcuts that engine
may have been subjected to. The damage to the blades may be from contact
rather than coolant, so perhaps the globbed on RTV was in conjunction
with a thin paper gasket wrongly used.

As others have mentioned, I would stay away from the aftermarket pumps
with stamped sheet metal impellers and get a cast solid impeller whether
metal or composite.

Mark

neil N wrote:
> Heat. Yes of course. I assumed the plastic material was somehow
> reacting poorly with water/coolant mix.
>
> It is an interesting wear pattern on the one I pulled though. I'm
> going to double check the housing for wear.
>
> Cheers,
>
> Neil.
>
> On Feb 20, 2008 6:26 AM, Dennis Haynes <d23haynes57@hotmail.com> wrote:
>> I guess I stand corrected regarding the composite impellers. I have not
>> seen them. My bet is that any type of engine overheating would mean the
>> end of them.
>>
>> Dennis
>>
>>