Excessive end play on oil pump shaft - 06 XB12X

[Curious_George]

6 Months or so ago, the oil pressure light came on just as I was pulling out of the drive. Killed the bike and pushed it back into the shed. Tore the oil system apart and couldn't find anything wrong, put it all back together and there was no problem. Left me a bit baffled.

Same thing happened today - got about 200m down the road, oil pressure light came on. Long push back home and began pulling things apart.

-Bike has the right amount of oil
-Oil gets to the pump
-Oil filter is full
-Driven and drive gears are both in good condition

When I pulled the pump off, I noticed that there was a large amount of play in the shaft. I'm talking around 4mm of play. Upon tearing the pump down, I found that the play was enough that the shaft will disengage from the lower pump! I can't see any significant wear inside the housing that would cause this, the circlip and washer are present and in good condition - it really has me baffled. It's almost as if the detent for the circlip has been machined in the wrong place or the shaft is too short - both very unlikely I know.

I've asked over on BadWeB as well, with some pictures, however if anyone has seen anything like this before, or is able to offer any advice, it would be most appreciated.

Cheers

 

[user_deleted]

refer to service manual schematic or google "buell xb early oil pump schematic" for reference pic if you don't have the field manual. look at parts identified as numbers 11&12. in all likelihood source of your excessive end-play. i assume here that your approx. 4mm "play" is end-play and not lateral slop.

 

[Curious_George]

Looking at the following image, part #9 is able to move up and down along it's axis within the pump housing. There is enough movement that it is able to just disengage from part #11, so that when turned, #10 rotates but #11 doesn't.
When the lines are hooked up and the pump is rotated by hand, it all works fine, and oil is pumped as expected by both the main and the scavanger pump. However when the shaft is lifted and turned (as is the case when the engine does it) there is enough play that only the scavanger pump will turn, not the main pump.
Everything is assembled correctly as per the schematic.
When #9 is lifted away from the housing, #3 and #4 stop it from coming out, however it's almost as if the surface that #3 contacts isn't thick enough. I can't see any signs of it being ground down, but that is the only explanation I can think of.

 

[Chicknstripn]

I believe the manual has wear limits for the gears. The actual thickness of the gears maybe out of spec and that could be causeing your end play issue.
Does that make sense or do I need to study the service manual cause I'm missing something?
I believe you can replace the internal parts to the oil pump.
I'd rebuild it and call it a day

 

[Curious_George]

The wear limits in the manual talk about the clearance between the individual gears of the pump, and a quick check with the feeler gauge says that they are in spec. There is no spec listed for axial movement of the shaft within the housing.

This is how much the shaft can move out of the housing

When the shaft is moved fully, it just disengages from the lower gear

It doesn't seem to matter which way up the gear is installed, it will clear it either way.

I'm not sure that a rebuild of the internals will fix it, as they all look correct. It seems as if the pump housing has worn internally, allowing the thrust washer to move - I get the feeling it's new pump time

 

[Chicknstripn]

Wow, I wasn't even thinking it could be the housing.
Your case is the first I've hear of that involves a housing being worn out.
Have you found any metal shavings or what not in your oil?
Can you see any signs of internal wear on the housing?

I would love to see a side by side comparison of your oil pump end play and a new pump.

Good luck bud. You seem to be trouble shooting this issue extremely efficiently.