Water pump impeller to housing clearance?

[Tony Tee]

picked up a couple nice waterpump housings at the fma show here in Ocala Fl

orida yesterday. And the clearance without a gasket measured .187" on one. and .225" on the other... In the past, I remembered that the impeller would touch the the housing without a gasket. What is the correct clearance? And does it really matter? Thanks in advance, Tony.

 

[snakeoil24]

.60

 

[Fran Blacker]

No gasket no turn on one of mine.

 

[RemCharger]

.60

0.060 ?

 

[steve340]

I think the clearance would matter in that the pump capacity to move water would decrease as the gap got wider. Too close may encourage cavitation which can do unseen damage.
The pump would also need to have a gap to "bleed off" flow when the thermostat is closed especially if the heater core has been blocked off.
The pump impellor in your picture has a lot of vanes and would likely move a fair bit of water as opposed to a 6 or 7 vane impellor.
The clearance you quote seem a bit big to me - but would probably work OK. An automotive water pump is only there to circulate the water but you don't want it to move the water either too fast or too slow.
I am only guessing really - optimal 70 to 80 thousands including the gasket with that impellor.
Good question.

 

[RJRENTON]

I think the clearance would matter in that the pump capacity to move water would decrease as the gap got wider. Too close may encourage cavitation which can do unseen damage.
The pump would also need to have a gap to "bleed off" flow when the thermostat is closed especially if the heater core has been blocked off.
The pump impellor in your picture has a lot of vanes and would likely move a fair bit of water as opposed to a 6 or 7 vane impellor.
The clearance you quote seem a bit big to me - but would probably work OK. An automotive water pump is only there to circulate the water but you don't want it to move the water either too fast or too slow.
I am only guessing really - optimal 70 to 80 thousands including the gasket with that impellor.
Good question.

IMO.....the CLOSER the impeller to the housing, the better. It reduces or eliminates any possibility of any cavitation or re-circulation of the coolant from the blade tips back to the "eye" of the impeller reducing the pump's capacity at any RPM. it appears from your pix, the pump is a Flowkooler design and definitely moves more coolant (velocity) for better heat transfer both in the block and radiator. BTW.....in a B / RB water pump housing, the coolant bypass is a cored hole directly under the t-stat so a separate bypass is not required as in the LA engine. The impeller to housing clearance should be ~ 0.040" - 0.050"......
BOB RENTON

 

[snakeoil24]

0.060 ?

Yes sorry .060 that's for all applications use silly putty to help confirm