# Water Pump Shaft Undersized (new pump)



## Gordie (Aug 7, 2021)

Hi all, I’m new to the site but look forward to getting to know the folks here.
I bought a MF 202 Workbull a while back and I’m still working on getting to the point where it can be used. It has the same engine (Z134), and water pump as TO35, which I also own. Part of the attraction in buying the 202 Workbull is that a lot of the parts are the same as the TO35. Any the 202 runs but the hydraulics didn’t work ( seized driveshaft in pivot pin). I’m getting that nearly sorted and am getting ready to start the reassembly. But before that I’m replacing the water pump. (The old one is loose and leaks a bit). Anyway I bought a new pump through Sparex up here in Canada but the shaft is .002 undersize when compared to the old pump. The pulley is supposed to press on but just drops on. Anyone else run into this or did you happen to buy a pump from someone else with a larger shaft? The old shaft measures about .7482 and the new shaft . 7462. It’s exactly .002 of an inch smaller so there isn’t an interference fit with the pulley. The pulley measures .748 exactly. So with the old pump I figured there was .0002 or .0003 tenths of a thousands interference.
I can knurl by hand or pock mark the new shaft if I have to and use loctite but if I can buy a pump with the larger shaft I would rather go that way. Sparex measured 2 other pump shafts for me but the also measured .002” under the original pump shaft.
Any suggestions or input would be appreciated. My background is in the mechanical trades where I deal with slip fits and interference fits daily but I’m wondering if this is how all the pumps are sized or perhaps a new pulley would be sized to fit. ( sparex told me they can no longer get the pulley). Thanks Folks
Gord


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## Gordie (Aug 7, 2021)

Thanks
Gord


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## sixbales (May 18, 2011)

Good morning Gordie, 

Return the pump to the supplier and explain the problem. He may have another pump that has the correct shaft diameter. It might also be that your fan connector is worn oversize??


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## Gordie (Aug 7, 2021)

sixbales said:


> Good morning Gordie,
> 
> Return the pump to the supplier and explain the problem. He may have another pump that has the correct shaft diameter. It might also be that your fan connector is worn oversize??


Hi, Thanks for your reply. 
I did call the supplier and they measured 2 other new pumps and they were also .002 undersized. I can return the pump if I wish but I still need to buy a pump with a larger shaft. My pulley bore is sized to fit the original pump. If they made rebuild kits for my pump I would just rebuild it, but they don’t.
They told me there is a manufacturing problem with the Pulleys and that’s why they can’t get them. Hmmm, I almost suspect the manufacturing problem is with the pump not the pulley. Anyway I will probably knurl the shaft and loctite it if I can’t get a larger shaft pump.


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