Author Topic: oil pump - help! (Read 4321 times)

Fourme · « **on:** January 19, 2019, 07:16:37 PM »

Does anyone have advice on how to remove the bushing in the CB750 oil pump ('72)? This has me stumped. Any help would be much appreciated.

Tracksnblades1 · « **Reply #1 on:** January 19, 2019, 07:36:14 PM »

What bushing are you trying to remove?

Tracksnblades1 · « **Reply #2 on:** January 19, 2019, 07:42:37 PM »

Here's some oil pump specs while your there.
Mirko, at MessnerMoto, manufacturers new billet oil pump rotors.
Check your primary chain while you're right there.....

Fourme · « **Reply #3 on:** January 19, 2019, 07:52:44 PM »

I believe it is number 12 and tried to attach a photo.

Tracksnblades1 · « **Reply #4 on:** January 19, 2019, 08:13:56 PM »

Shaft seal...?
Is it still good..?
Have you check to see if its available...?

Fourme · « **Reply #5 on:** January 19, 2019, 08:15:38 PM »

Its not good and I have a replacement.

kmb69 · « **Reply #6 on:** January 19, 2019, 08:18:58 PM »

Still available from Honda:
OIL SEAL (11X15X3) 91208-MN1-771 (replaces 91208-300-003)

Tracksnblades1 · « **Reply #7 on:** January 19, 2019, 08:21:26 PM »

What is stopping you from removing it?
Do you have seal puller tool?
Brass drift.?

Fourme · « **Reply #8 on:** January 19, 2019, 08:30:39 PM »

It can't be tapped out from the "back side" and I just can't get a puller to grip.

Tracksnblades1 · « **Reply #9 on:** January 19, 2019, 08:39:12 PM »

Sometimes you gotta improvise...😎
Your probably going to sacrifice a tool to make one that can get behind it and pry, twist it out. Brass would be better than an old screwdriver. I'll try to find a 90degree tool picture that may spark your imagination.. I know it's a small one. I have had good luck removing needle bearings, bushings, and seals, in shouldered bores with improvised intake, exhaust valve faces, of various sizes, purposely ground, sharpened , cut, and modified to get behind such when the perfect tool is not available. Using the stem as the means to pry or drive it out.

Be careful not to damage the aluminum.😇

PeWe · « **Reply #10 on:** January 19, 2019, 10:02:48 PM »

Vital motorparts sell a complete kit for the pump. There is a thread about pump restoration and that hard sitting seal. Forum member Elan started one thread.
https://www.ebay.co.uk/itm/Honda-CB750-Oil-Pump-Rebuild-Kit-SOHC-O-Ring-Stopper-Seal-/162442240391?_trksid=p2349526.m4383.l4275.c1

trigger · « **Reply #11 on:** January 20, 2019, 12:47:10 AM »

I have replaced hundreds of these seals over the years and you will find that one will just pop out and, the next will be a stubborn #$%*. Some that we have tried to remove has ended in damaging the pump body ( pic) where the common sense says, "walk away, walk away and come back to it" but, the little devil inside is determined not to be beat.

After a lot of thinking we came up with the ideal tool, a simple tap. Remove all the rubber from the seal with a scapel leaving just the metal case of the seal. Knock the tap in so it grips, turn and it is out with no damage whatsoever

70CB750 · « **Reply #12 on:** January 20, 2019, 03:11:22 AM »

Quote from: trigger on January 20, 2019, 12:47:10 AM

I have replaced hundreds of these seals over the years and you will find that one will just pop out and, the next will be a stubborn #$%*. Some that we have tried to remove has ended in damaging the pump body ( pic) where the common sense says, "walk away, walk away and come back to it" but, the little devil inside is determined not to be beat.

After a lot of thinking we came up with the ideal tool, a simple tap. Remove all the rubber from the seal with a scapel leaving just the metal case of the seal. Knock the tap in so it grips, turn and it is out with no damage whatsoever

Now, that´s clever.

Fourme · « **Reply #13 on:** January 20, 2019, 06:13:57 AM »

Awesome, thank you. Do you happened to know the size of the tap?

trigger · « **Reply #14 on:** January 20, 2019, 06:57:01 AM »

Quote from: Fourme on January 20, 2019, 06:13:57 AM

Awesome, thank you. Do you happened to know the size of the tap?

We couldn't find a M15 laying about so found a old M16 x 2, flat nose and kept grinding the end until it was a good fit.

Fourme · « **Reply #15 on:** January 20, 2019, 09:03:59 AM »

Thanks again.

754 · « **Reply #16 on:** January 20, 2019, 09:15:40 AM »

I was thinking abou this, and if there was a bushing behind it, I would have said use a tap.
But not sure if it could scar something behind its or not.
So, I think a screwdriver shaped piece with 2 bends would work. The main part above the seal with room for a word or alloy shim....the tip, bent to get I to and under the seal, the pry it out, no damage.. polish the tip..

PeWe · « **Reply #17 on:** January 20, 2019, 09:27:14 AM »

Good to know.
I'll look for M15 and M16 at my job's lab's workshop's box for no longer used tools.

Mantree · « **Reply #18 on:** October 11, 2021, 08:58:46 PM »

I am having this same issue. Do you think heating it with a torch on low would do the job?

Mark K · « **Reply #19 on:** October 13, 2021, 08:46:45 AM »

I just replaced the same seal, should have left well enough alone (hindsight), but thinking it was just another type of rubber o-ring, I picked and scraped until I realized it has a metal backing. I placed the main piece in my vice to hold it (with aluminum angle stock covering the vise jaws), and then used a small jewelers screwdriver and small hammer to tap/pry the outer edge to bend it. A couple small pieces of the metal seal frame broke off, and then the whole thing popped out. Probably not the best method, but as I'm finding out thru trial and error (many errors!), it pays to research this forum first before attempting an unknown disassembly/repair/reassembly on my '73 CB750. 😉

I didn't think to try heating the body around the seal, even though I have a torch on my workbench in plain sight. Good luck!

Don R · « **Reply #20 on:** October 13, 2021, 09:34:44 PM »

I have one to go through next spring, thanks for the info.

Kook652 · « **Reply #21 on:** August 08, 2022, 04:56:53 PM »

Quote from: trigger on January 20, 2019, 12:47:10 AM

I have replaced hundreds of these seals over the years and you will find that one will just pop out and, the next will be a stubborn #$%*. Some that we have tried to remove has ended in damaging the pump body ( pic) where the common sense says, "walk away, walk away and come back to it" but, the little devil inside is determined not to be beat.

After a lot of thinking we came up with the ideal tool, a simple tap. Remove all the rubber from the seal with a scapel leaving just the metal case of the seal. Knock the tap in so it grips, turn and it is out with no damage whatsoever

This is brilliant and works as described. Thank you.I tried drilling, prying, heat.............the.... My seal popped right with an M17x2.0 tap.

beemerbum · « **Reply #22 on:** August 08, 2022, 06:05:36 PM »

Save time, aggravation, worry, work and money. Order a rebuilt pump from Ken at CycleX

xhevi · « **Reply #23 on:** October 07, 2022, 09:57:32 AM »

Quote from: Kook652 on August 08, 2022, 04:56:53 PM

Quote from: trigger on January 20, 2019, 12:47:10 AM
I have replaced hundreds of these seals over the years and you will find that one will just pop out and, the next will be a stubborn #$%*. Some that we have tried to remove has ended in damaging the pump body ( pic) where the common sense says, "walk away, walk away and come back to it" but, the little devil inside is determined not to be beat.

After a lot of thinking we came up with the ideal tool, a simple tap. Remove all the rubber from the seal with a scapel leaving just the metal case of the seal. Knock the tap in so it grips, turn and it is out with no damage whatsoever

This is brilliant and works as described. Thank you.I tried drilling, prying, heat.............the.... My seal popped right with an M17x2.0 tap.

did you use m17x2 tap as they come or did you have to do any grinding to it? tapered or bottom tap?

thank you.

xhevi · « **Reply #24 on:** October 09, 2022, 06:14:57 PM »

After going to three hardware stores looking for a m17 or m15 tap. I gave up. Not many stores in US would stock that big a metric tap.

However I was able to pull the seal with a simple carpet staple remover that I already had. If I remember correctly I bought this at a Sherwin Williams store years back for about 7$. They still sell it if you don't have one.

I used a file to sharpen the tip to get to the seal from behind (through the shaft hole), that did not work.

Then tried from the seal side and it came out easy. It happens to be the right size and it's plenty rigid to pry the seal out.

Hope this helps the next member rebuilding the oil pump. And if you don't have have it already, now you know where to get it.

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Author Topic: oil pump - help! (Read 4321 times)