Wear ring replacement problem

[brad]

On my 96 xp I recently replaced my wear ring. When I tighten up the impeller shaft the impeller will not turn.(it binds on something). It is so tight in fact that the starter will not turn the ski over. So I tried (expirementally) just leaving the shaft hand tight. But I found out the shaft is self tightening and this doesnt work either. So the question is....what should I do to help relieve the binding? Does the "wear ring" just need to be "wore in"?

[John Kubiak]

The thrust bearing is being pinched by the impeller shaft! You need to remove the pump, remove the impeller, remove the impeller shaft from the pump housing, Then replace the thrust bearing with a new, un-damaged one. Carefully reassemble everything, making sure not to damage anything!

Good Luck!

[brad]

Does the thrust bearing wear out?

[John Kubiak]

No, but they get damaged when they aren't assembled carefully!

[SP]

Do you remember seeing a groove cut in the impeller shaft?

You need to put grease on the thrust bearing during assembly to keep it from dropping in to the groove.

[Bill O'Neal]

Pinching the bearing is usually the cause of this problem, per John's advice.....

But, just last week I had a 99XPL that had a torn up wear ring that needed replacement. I installed the new wear ring and the old impellor locked up in the wear ring as I tightened it the last half turn. I could loosen it a half turn and it would spin freely. I disassembled the pump again to check, thinking I had pinched the flat bearing. No such problem.
I then got a new flat bearing and thrush washer and installed them, thinking maybe the flat bearing had worn over the years to where it was allowing the shaft to tighten up in the back of the pump (hey, just fishing here for the solution). That didn't help either.
I went into my parts room and got another oem impellor and installed it. Bingo ! It spun freely when tightened. Problem solved.
I figured when the prop processed the wear ring pieces through the pump, it slightly bent the blades outward, causing it to get larger in diameter.

Old aluminum pumps that get dropped onto the concrete get egg shaped, so when you install the impellor, it drags on one side of the wear ring. This can usually be overcome using WD40 and the starter motor to self-clearance the wear ring with the impellor blades. Not so if too egg shaped.

Some aftermarket impellors are not the right diameter. My guess is that the operator of the lathe was reading Playboy when he was cutting it.....

But, usually, a novice mechanic will pinch the flat bearing when installing the impellor. You must keep the shaft pushed through the pump so that the shaft does not fall back, allowing the flat bearing to drop into the groove at the base of the shaft. The best way to assure this does not happen is to mount the flat sides of the shaft in the vise with the pump pointed straight up at the ceiling. Unwind the old impellor and install the new impellor, then using the blades to lift the whole thing from the vise to keep the shaft tight to the bearing, move to the bench and install the cone without letting the shaft to move back. If you think you may have allowed the shaft to recede, you probably did. Disassemble it and look to see if the bearing is still centered before you tighten the three cone bolts, or push the cone on by hand to seat it. If it completely seats by hand, without the use of the cone bolts to draw it tight, your bearing is ok. Using a heavy grease will help keep a bearing in place while assembling, but you still need to be careful. When all is done, with the cone installed, you need to grab the prop and move it back and forth, in and out of the pump. If it will not move a few thousandths in and out, you have a PINCHED bearing and if you run it for even a FEW minutes, you will ruin the bearing race seat in the pump and you will have to BUY a new impellor housing.

How many guys have tried to save a buck by doing it themselves and ended up buying pumps ? Plenty.......

Never try to use the flat bearing after it is pinched. Always replace it with a new bearing or you will be buying an impellor housing soon.

[ August 23, 2002, 09:41 AM: Message edited by: Bill O'Neal ]

[SP]

Did anyone notice that using a replacemet pump cone with spring pusher on an older pump that used a non-spring type pusher will allow enough movement of the impeller shaft to allow the thrust bearing to fall in to the impeller shaft groove.

Watch Out......

[brad]

Sp, that is exactly what was happening. The bearing fell into the impeller shaft groove. Causing the bind. Now I also found that the cone will not mount flush to the pump housing if this bearing is not set properly. So that is a good indication that there is an error in assembly. I checked out the pump housing and the bearing, they both looked in good shape to me. (after all I am a tool maker) So I re-assembled according to bill's comment and all went well. There is now play in the prop and it spins freely. Thanks for all of the help guys.

Brad

[ August 23, 2002, 10:04 PM: Message edited by: brad ]

[thomas]

Found this old subject and would like to add something. I agree with Bill about a new or reworked impeller coming back with a outer diameter size that doesn't quite fit. I'm having the same problem trying to get this impeller into my 99XPL. When I did get it in, it rubbed so hard that the starter would barely turn the motor. Screwed up my new wear ring. Now I'm goin to send it along with a new wear ring to get fitted.

[Bill O'Neal]

If it only rubs on one side it is being caused by a wraped housing. Not much you can do about that.

If it rubs all the way around, the impellor will cut it's own path, and will not be a problem.
You will not really notice any differences in performance by sending it in to get it "fixed".

If the impellor is way too big, it won't start at all.

[thomas]

Ok, I agree, the blade will eventually cut it's own path thru the wear ring. But that's not why I bought a new wear ring. Doesn't a perfectly smooth wear ring work better than one that has grooves in it? I thought this is where cavitiation could come from?