Bosch water pumps- buyer beware
 

So I recently purchased two bosch water pumps for my d24's. One has the good cast impeller and the other has the lower performing stamped steel impeller. I have always purchased the bosch pumps because of the cast impeller.
It looks to me they changed over to the cheaper to produce stamped impeller.

How do you all feel about the polymer impellers?

I recently replaced my orig. cast impeller WP with a new GMB (smaller dia. BTW) stamped steel impeller WP during a timing belt change. Purposely did not change out the t-stat to run a little experiment. Currently the experiment shows little change in engine tendency to overheat. Engine runs same displayed temp as before, and has not risen during high load, also as before.

I kept the cast impeller WP with the idea to eventually rebuild it w/ new bearing and seal.

I own and operate a Euro auto garage. The plastic impellers crack and as a result slip and do not pump. At times they shatter. The stamped steel ones come loose also. Cast impeller is best. VW uses plastic in all of their OE pumps.

I have had the Bosch pump in my engine for a while now... I know of a few members on the D24 list that have had great results with them.. They are the plastic impeller, but they are a copy of the original and its a very thick impeller by design, unlike the newer VW pumps that are thin crap. Given the choice a steel impeller would be best, but at this point I feel like we should be happy that much of anything is still being reproduced for these engines!

Jason