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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: Howard64180 on May 16, 2015, 12:48:54 PM
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OK, I'm stuck. I have replaced the oil and water pump seals for the second time (1989 K100). The second time everything went according to plan. And then I noticed. The pump drive gear is flush with the pump face, or even slightly recessed. Until I turn in through 180 degrees, when it is standing slightly proud. So it's flush on average :yes The gear shaft is in very good condition.
On the inner side of the gear the gap is less than 2 thou in some parts of the rotation, slightly more in others. Everything turns as freely as you would expect.
When the gear is standing proud, it is possible to temporarily press it down flush. Is the gear likely to line up when the case is tightened down, or is it more likely to bind on the engine case? I don't really see how the fitting of the seals can be at fault, as there seems to be some play in the mechanical seal that would allow for sideways movement anyway. However, I would be happy to be told I'm wrong, at least it would be a way forward. When the pump is offered up to the engine, no gap is visible to the naked eye between pump/engine.
I have searched for answers to this, but found none.
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Well, thanks to a poster on another site (can I say that?), it's now sorted. Despite the tiny clearance on the inside of the gear, I decided to use a washer to pull the shaft through a little further and it worked. If there is any interference between the pump gear and inner pump face I can't feel it. One happy Motobricker.
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got any pics, or a link to a thread on this other site? Just curious.
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need pics to visualize this :popcorm
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I know what you're talking about now. When I was attempting to re-seal my pump I also used an additional washer to pull the shaft and gear in farther so it was just a tiny bit inside the housing so it wouldn't rub on the engine.
So much for that experiment...I ended up saying F it and installed a used one
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Sorry, no pics (none on the other site either). Basically, as the pump drive gear rotated it wasn't flush with the face of the pump housing all the way round. It has to be flush to stop it rubbing against the engine. I was concerned about pulling the gear and shaft too far so that the inner face of the gear would rub against the pump housing.
The poster on the other site said that the gap between the inner face of the gear and the pump should be as little as 20 thou - if not, pull it in further. Mine was actually less than this in some positions but I decided to go for it anyway because I also read this: http://www.bmbikes.org.uk/Forum/viewtopic.php?t=15729.
So I thought, if I go too far I can tap it back a bit. I had nothing to lose really (except the cost of more seals), as I couldn't assemble it as it was. I hope I have more success than F14CRAZY, but I won't know for quite a while as I have much more work to do before I have a runner. I just saw a new pump on Ebay - only £360 (plus postage) :yow