Topic: Oil pump rotor punch marks

[the-chauffeur]

I'm in the middle of overhauling my oil pump, and have found that both sets of rotors (scavenge and delivery sides) have punch marks on them (one side only).

I know the punch marks of the inners and outers need to be facing the same way, but should they be facing into or out of the pump body assembly - or does it matter?

Thanks all.

[Jerry Rxman Griffin aka MuthaF'er]

I don't know "the book" answer that neither of us managed to find and I have 4 manuals.  I just put mine back together yesterday after replacing the gear shaft seal and both o-rings in the body and the leak stopper plug, it's spring and o-ring in the base as well as the filter screen. I decided that the dots should both be on the same side and visible when they go in. If not visible how would you ever know?! Been too long since I've taken a "virgin" pump apart to remember. I'm sure someone will chime in here that has just opened up a pump or is smarter than I am in this regards.   

[the-chauffeur]

Thanks Jerry.

Like you, two manuals are silent on the subject.  Hondaman's book mentions the marks, but not the orientation, so I guess it's not that important so long as they're facing the same way.  I was just a little concerned that they might have some kind of secondary function - like oil distribution - but that seems pretty unlikely.

It's gonna be a few weeks before mine goes back into an assembled engine, so I'll keep looking for answers.  Meantime, I also need to order me one of the centre shaft seals, too (already done the larger o-ring swap).

Cheers.

[Jerry Rxman Griffin aka MuthaF'er]

Do you have the part number? You won't find it listed for the 750. It's a 750 part number that is listed under Gold Wing, go figure. 91208-300-003

Removing it safely without damaging the pump housing is tricky at best. It has a steel outer ring that presses into the softer aluminum. I tried a couple approaches. Tried to get between the steel ring and aluminum body without success. Trimmed the rubber off and took my blind bearing puller to it without success. Carefully tried a chisel on it to no avail. Finally put it in the freezer overnight in my ice dispenser and managed to get a small screw driver blade under the bottom inside edge and managed to work it out. Banged up the hole marginally but enough to impede the shaft. Actually used the shaft to help push out the small imperfection and shave it with a fresh blade in my razor knife. Tapped the new one in with a small hammer.

[MCRider]

The punch marks face out, respectively. How do I know. I've disassembled 3 pumps, they were all that way.

My answer for a rebuilt pump for my project? I found one on eBay with 7500 miles on it. Looks like new.

[a700guy]

usually the side of the outer rotor with the larger bevel, if it has one goes to the inside and the inner rotor orients to match. But alot of the more modern engines have generous radius fillet inside the oil pump housing at the rotor.

[the-chauffeur]

Thanks all.

I've got the seal on order now.  Hadn't tried pulling the existing one - wow . . .they're nasty little sods to pull out, aren't they?  Just had a go at an old pump, and the seal didn't want to come out without a fight.  I'm gonna stick the good pump in the freezer before I attempt that one.

[bryanj]

Not too close to the Sunday dinner tho' mate it will ruin the flavour