Author Topic: More water pump blues  (Read 3662 times)

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Offline yojimg

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Re: More water pump blues
Reply #10 on: December 11, 2019, 11:10:09 PM
*Originally Posted by Gills [+]
See bigbobby's reply #11 here: https://www.cb500x.com/index.php?topic=5285.11 A number of the pumps in stock at his dealer had bent shafts. It may be that there are bad batches around. :003:

Yep.  I've checked all of my pumps (I now own 4!) and their shafts all have about 0.010" of runout.  There's another water-pump thread here that I've posted videos in.

Offline timur

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Re: More water pump blues
Reply #11 on: December 12, 2019, 09:22:22 AM
*Originally Posted by yojimg [+]
Yep.  I've checked all of my pumps (I now own 4!) and their shafts all have about 0.010" of runout.  There's another water-pump thread here that I've posted videos in.

I think there would be another reason for such systematic failures - misalignment between oil pump and water pump shafts. Water pump is driven by oil pump so their axis noncoincidence will produce vibrations and bending loads on both shafts.

This would explain why on some bikes water pumps leaks every 10000 miles and on another they last forever. In this case I suppose there must be signs of wear inside the groove on end of water pump shaft :084: Yojimg - has your pump shafts some visible wear there?

Offline yojimg

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Re: More water pump blues
Reply #12 on: December 12, 2019, 06:49:19 PM
*Originally Posted by timur [+]
I think there would be another reason for such systematic failures - misalignment between oil pump and water pump shafts. Water pump is driven by oil pump so their axis noncoincidence will produce vibrations and bending loads on both shafts.

This would explain why on some bikes water pumps leaks every 10000 miles and on another they last forever. In this case I suppose there must be signs of wear inside the groove on end of water pump shaft :084: Yojimg - has your pump shafts some visible wear there?

I've started wondering the same thing -- like maybe the culprit is actually the oil pump, which drives the water pump?  That said, I haven't noticed any visible wear in the drive slot of any of my water pumps, nor on the drive tab on the oil pump itself.  I'd like to examine the oil pump's drive tab spinning, but that would require turning over the engine with the water pump removed....


Offline yojimg

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Re: More water pump blues
Reply #13 on: February 16, 2020, 05:16:50 PM
Barely 1000 miles on my 4th pump. And itís started weeping again.  WHAT THE HELL?!?

Online motorboy

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Re: More water pump blues
Reply #14 on: February 17, 2020, 04:15:35 AM
I think timur maybe on to something-four pumps all bad the odds are to high to count-time to tear that side of the engine down-you do know what Einstein said about doing the same thing over and over :138:
It's not a big motorcycle just a groovy little motorbike

Offline racer

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Re: More water pump blues
Reply #15 on: February 17, 2020, 09:03:19 AM
Try putting a dial indicator on the shaft and rotating it.  I'll bet you will find your problem lurking there.  Racer

Offline yojimg

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Re: More water pump blues
Reply #16 on: February 17, 2020, 04:27:00 PM
*Originally Posted by racer [+]
Try putting a dial indicator on the shaft and rotating it.  I'll bet you will find your problem lurking there.  Racer

See above. I've checked all of my pumps (I now own 4!) and their shafts all have about 0.010" of runout.  There's another water-pump thread here that I've posted videos in.

Online Neox

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Re: More water pump blues
Reply #17 on: February 17, 2020, 08:09:16 PM
Bad machining of the crankcase?

Online Neox

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Re: More water pump blues
Reply #18 on: February 18, 2020, 12:05:14 AM
More than 5 defective pumps, it seems strange to my eyes...
So it could be another parts being wrong and make failure of the pump.
Bad alignement between the hole supporting the shaft? Bad joint plan? Bad bore tolerance? Bad place(too deep?) for the seal?

Offline Falang

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Re: More water pump blues
Reply #19 on: February 18, 2020, 11:37:56 PM
I notice that both of you live in places which can be hot during the riding season. I wonder if this water pump failure problem is also experienced by people in cold countries.