Author Topic: Water pump oil leak  (Read 7396 times)

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Online Neox

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Re: Water pump oil leak
Reply #90 on: September 28, 2020, 03:58:08 PM
Design of the old pump:


Design of the new pump:


The oil pump is on the right side of the engine:


The water pump is on the ... left side of the engine:


So the shaft go through... the gearbox:

As we can see the water pump housing is against the biggest pinion, that's why the body of the new pump is shorter than the oldest one. The engine is more compact compared to the '98. The gear shifting is upper and not under like on the old one.

But on the new one like on the old one I find the screws position is not so good, too much on one side of the pump.

edit: it's not my engine :001:, I find the pics on the web...
Last Edit: September 28, 2020, 04:02:36 PM by Neox

Online Neox

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Re: Water pump oil leak
Reply #91 on: September 28, 2020, 04:01:32 PM
I tried to put the photos on the gallery of the forum but he wouldn't connect me although the name, password and captcha are correct :027:.

Offline Halfricatwin

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Re: Water pump oil leak
Reply #92 on: September 28, 2020, 07:48:05 PM
Good photographs Neox, thanks. The "old" water pump certainly looks a lot more robust - pump shaft appears to be far better supported. Having done a bit of looking around I can see that the slotted joint, at the point the oil and water pump shafts meet, doesn't appear to be restricted to Honda. In fact it looks like an industry standard joint that's common to other manufacturers. Water cooled bikes are a new thing for me, all my other bikes are air cooled vintage machines, hence my ignorance. Still, seems an odd way to join those two long shafts to me - clearly some engineering logic that I'm not up to speed with. But that CAE designed driveline coupled to that smaller/lighter water pump? Makes me wonder what the guys at Honda think about that layout, post production.
 

Online KennyV

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Re: Water pump oil leak
Reply #93 on: September 28, 2020, 08:40:20 PM
This really good information, thanks!  :762:
71 Z50 Minitrail, 72 Yamaha RT2 360, 74 Yamaha DT250A, 20 CB500X

Offline BenjaminCB

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Re: Water pump oil leak
Reply #94 on: September 29, 2020, 03:28:20 PM
nice pics you found there mate

Online Neox

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Re: Water pump oil leak
Reply #95 on: September 29, 2020, 11:21:39 PM
I think that if you remove the oil pan it is possible to see the rotation of the shaft and its connection.
Not so easy but maybe possible to mesure the false round of the shaft's rotation mounted in the engine :084:.

Offline motorboy

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Re: Water pump oil leak
Reply #96 on: September 30, 2020, 01:10:25 AM
After reading all this-it's got me wondering why--let me throw this out there-could it have anything to do with how the bike is warmed up and dissimilar metals heating at a different rate causing wear
It's not a big motorcycle just a groovy little motorbike

Online Neox

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Re: Water pump oil leak
Reply #97 on: October 02, 2020, 12:15:33 AM
I don't think, if the manufacturer controlled the expansion so badly they wouldn't be able to make a running engine :084:.

What about a too long shaft? Possible to push on the joint and make it leaking?

Offline Halfricatwin

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Re: Water pump oil leak
Reply #98 on: October 02, 2020, 03:28:33 PM
I don't think you have to look much further than the photographs supplied by Neox comparing the old model 500 twin's water pump to ours - the latter being the "new and improved" design which features that very long, very probably insufficiently supported, pump shaft. By the time the drive reaches the water pump body on the left hand side of the crankcase the induced run out has created an oval rotation instead of a perfectly circular rotation. This accelerates the wear of the internal oil and water seals. If that's not enough, add the evidence from some on this site stating that some of these pump shafts are actually out of true at the time of manufacture. The result is exactly what we are seeing now. Some bikes will fail quicker than others and who knows - some may actually go the life of the engine. I'm on my (recently installed) second water pump at 5,700 kms. Not particularly unusual as we now know, but simply staggering for a brand new 2020 model Honda purchased just over four months ago. While "one off" failures can reasonably be expected, the systematic failure we are seeing here is something else altogether. I strongly suspect Honda dropped the ball on the redesign of this water pump to the point that, if we were talking cars instead of bikes, a redesign/recall would have been issued long before now. :006:

Online Neox

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Re: Water pump oil leak
Reply #99 on: October 02, 2020, 11:54:46 PM
*Originally Posted by Halfricatwin [+]
I strongly suspect Honda dropped the ball on the redesign of this water pump to the point that, if we were talking cars instead of bikes, a redesign/recall would have been issued long before now. :006:
The water pump shaft is too close to gearbox pinions to be changed.
all the engine should be redesigned!

i think kawa and yam make pumps driven by the motor balance shaft because it is located in front of the motor, and not above the gearbox as on the CB.

 



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