[C320-list] Impeller Puzzler

[Tim]

Ok, I'm hoping someone can share some insight here as I've given up. This spring as part of normal comissioning I replaced the impeller for the water pump. I bought a yanmar part and side by side it's identical as well as matching part #'s. Here's the catch. With the new impeller installed, I could not get the pump to move any water. I even had the pump isolated (input into a bucket and output as well but not submerged) and still nothing. At wits end, I put the old impeller back in and all was well.
 
Anyone ideas what's going on?
 
Tim
Calypso
#603