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Jet Pump rebuild - score marks in shaft bore

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Any suggestions on removing fine score marks from the two 1.125" bore holes in the jet pump body (where the impeller bearings go)? There are some "minor" scractchs, nothing big, maybe a few thousandths max, but enough that it makes the bearing too tight on the shaft. I own a machine shop (industrial tooling), so I am not afraid to work on it, but I don't want to over-do it and ruin the bore.

Edit: It's a 1990 SP
 
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How did they get in there?? The housing is plastic knock the raise portions off with emery paper (120 grit or finer) but You'll have to get all the abrasive particles out of the housing. Polish it a bit then mic the bore. If you go a a little big, which you won't you can always use loctite 609. Good Luck.

Must be pretty bad if the bearing is tight on the shaft.
 
How did they get in there?? The housing is plastic knock the raise portions off with emery paper (120 grit or finer) but You'll have to get all the abrasive particles out of the housing. Polish it a bit then mic the bore. If you go a a little big, which you won't you can always use loctite 609. Good Luck.

Must be pretty bad if the bearing is tight on the shaft.
Sorry, mine is a 1990 - it is an aluminum housing. They got in there trying to get the old bearings out.
 
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In that case I'd try to only scrape only the raised areas of the groove and not remove metal in a general fashion. You are correct... you'll probably loose the fit if not done properly. Again... 290 can save you but it's not the prescribed method I'd like to use. Ha ha.

I have a 1/4" mandrel for the die grinder. The mandrel has a hacksawed slot in the center about 1" deep. I tear a piece of emery paper and wedge it into the slot. It works great for polishing and for doing what you are trying to accomplish because it doesn't remove much material. The emery needs to be longer than the hole so it will center up. Good Luck !!
 
So, I ordered another set of bearings (one of mine got messed up during reinstall). Second time around, I used the lathe to turn up a Delrin arbor to remove the bearings and an aluminum arbor for installing. Both arbors have an OD of 1.100" and a lead diameter of .870". The aluminum one for inserting is only a couple inches long with a lead of about ¼" with a short rod sticking out of the top. The Delrin one for removal is 8" long with a lead of 2". I used a hydraulic press (the Harbor Freight special ) for pressing them out and a Bridgeport vertical mill with a drill chuck to hold the aluminum arbor for pressure in (the Bridgeport is much more accurate at keeping the bearings perfectly vertical).

I used a Dremel with a drum to remove any swedged material from my first improper removal technique (punches and a hammer are NOT advised no matter what videos may say otherwise - lesson learned). I test fit a shaft to a bearing, checking it as I partially inserted it in the bore continually until I could insert it fully without any binding in the bearing. I wet sanded the bores afterwards and washed with soapy water, dried them with air, & then hit with brake clean for good measure.

It was time consuming, but it worked well. I do not recommend a hammer and punch for any bearing process. I wish I had known this ahead of time as it would have saved me $$ and days waiting for new bearings. Hopefully, my errors can save someone else the hassle.
 
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