impeller to pump clearance?

Anyone know what the maximum gap should be between the impeller and pump in a Yamaha 144mm pump?

The Yam 144mm pump is an axial flow pump, not tapered, & needs no shims. But, no, I don't know. JB.

A good impeller in a new wear-ring has about .007-.010' clearance per side. When you get .020' or more per side, it's time to have the impeller repaired (by welding the outside diameter and machining it back to correct size) or replace it. Under normal circumstances, even a wear-ring that looks worn usually measures very close to what it was when new- so it's not as common to have to replace that part (unless it's damaged from salt water or other debris). Since it is an axial flow, there's no shimming that can be done, it's either tight or it's not. Good luck, David Stewart

According to the OEM manual for SJ the clearance should be .012' - .016' That seems a little excessive but I borrowd a mag. pump at WF that had at least .025' clearance and it worked just great. Normally the tighter the clearance the better the hook-up (but don't go below .006' or pump 'crashing' can occur do to hull and prop flex in rough conditions)

Nate