The Ford Barn

Randy in Illinois · 06-21-2013, 02:07 PM

How far do you press the impeller on from the fan end of the shaft? one source says 8.455' or 29/64" from the back of the impeller to end of shaft. another source says 8 3/8: from the back of the impeller to end of shaft. maybe it's with the thrust washer on? need advice

Tom Wesenberg · 06-21-2013, 05:19 PM

I don't know the dimension off hand, but I know someone posted it in the past.

I had an impellor explode on me while I was pressing it on.

That made me think it might be worth buying the new shaft with the impellor already pinned in place.

Joe K · 06-21-2013, 08:09 PM

This may be one that is best done "experimentally." If you stick with the stock dimension (whatever it is) then you might find yourself with the need to do the "collar" trick on the front (under the fan) to keep your lateral motion below the recommended 0.010.

The game goes like this:
Press on
Assemble water pump from the rear bushing backwards (i.e. impeller in place on shaft with thrust washer etc, etc, just as you took it apart.)
CHECK to see how much free play you have (don't forget the gasket!)
Rinse and repeat to get the 0.010 or slightly less.

I say slightly less as this will make your water pump less likely to "pump" out the gland, be it a modern seal or the original graphite wick.

When you get your distance set, then drill and pin the impeller in place to prevent a heartache later as the fan "propellors" the shaft into the backside of your radiator and wipes a big circular indent into your radiator fins. (see the mode of failure here?)

With now 80 years of wear on that "bridge" inside your engine head, it's unlikely the original shaft dimension will be anything near what you need. And you can buy "extended" shafts to make up distance should an original fan shaft result in not enough out front to take the fan hub on it's taper.

(There are other solutions to the receding head bridge issue including drilled/tapped/bolted adjustable pump shafts, building up with weld, etc. All grist for discussion by those who have needed to do.)

Good luck with this. Pin that impeller - a lot of repop shafts are a smidge too small in diameter and result in insufficient "press/adhesion."

Joe K

ursus · 06-21-2013, 09:10 PM

Oil and chill shaft. Heat impeller and push onto the shaft. Let cool and it will shrink to a tight fit.

Randy in Illinois · 06-22-2013, 09:44 AM

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thanks for your input. Trying to set fan/pully position and end play with collor. I will pin the impeller. Looks like I will have to put in on the car and adjust and set.

06-21-2013, 02:07 PM	#1
Randy in Illinois Senior Member Join Date: Jul 2011 Location: Illinois Posts: 193	pressing on a wp impeller How far do you press the impeller on from the fan end of the shaft? one source says 8.455' or 29/64" from the back of the impeller to end of shaft. another source says 8 3/8: from the back of the impeller to end of shaft. maybe it's with the thrust washer on? need advice

06-21-2013, 05:19 PM	#2
Tom Wesenberg Senior Member Join Date: May 2010 Location: Mpls, MN Posts: 27,582	Re: pressing on a wp impeller I don't know the dimension off hand, but I know someone posted it in the past. I had an impellor explode on me while I was pressing it on. That made me think it might be worth buying the new shaft with the impellor already pinned in place.

06-21-2013, 08:09 PM	#3
Joe K Senior Member Join Date: Jul 2010 Location: Cow Hampshire Posts: 4,188	Re: pressing on a wp impeller This may be one that is best done "experimentally." If you stick with the stock dimension (whatever it is) then you might find yourself with the need to do the "collar" trick on the front (under the fan) to keep your lateral motion below the recommended 0.010. The game goes like this: Press on Assemble water pump from the rear bushing backwards (i.e. impeller in place on shaft with thrust washer etc, etc, just as you took it apart.) CHECK to see how much free play you have (don't forget the gasket!) Rinse and repeat to get the 0.010 or slightly less. I say slightly less as this will make your water pump less likely to "pump" out the gland, be it a modern seal or the original graphite wick. When you get your distance set, then drill and pin the impeller in place to prevent a heartache later as the fan "propellors" the shaft into the backside of your radiator and wipes a big circular indent into your radiator fins. (see the mode of failure here?) With now 80 years of wear on that "bridge" inside your engine head, it's unlikely the original shaft dimension will be anything near what you need. And you can buy "extended" shafts to make up distance should an original fan shaft result in not enough out front to take the fan hub on it's taper. (There are other solutions to the receding head bridge issue including drilled/tapped/bolted adjustable pump shafts, building up with weld, etc. All grist for discussion by those who have needed to do.) Good luck with this. Pin that impeller - a lot of repop shafts are a smidge too small in diameter and result in insufficient "press/adhesion." Joe K __________________ Shudda kept the horse.

06-21-2013, 09:10 PM	#4
ursus Senior Member Join Date: May 2010 Location: Oregon Posts: 1,375	Re: pressing on a wp impeller Oil and chill shaft. Heat impeller and push onto the shaft. Let cool and it will shrink to a tight fit.

06-22-2013, 09:44 AM	#5
Randy in Illinois Senior Member Join Date: Jul 2011 Location: Illinois Posts: 193	Re: pressing on a wp impeller Sponsored Links (Register now to hide all advertisements) thanks for your input. Trying to set fan/pully position and end play with collor. I will pin the impeller. Looks like I will have to put in on the car and adjust and set.