Topic: 1977 CB550K Oil Pump Cover O-Ring size?

[Maraakate]

I noticed some drip on the left side of my 77 CB550K awhile ago and thought it was the shifter seal.  When I took the cover off I found out that it was the bottom on the oil pump cover.  I verified this by cleaning everything up and starting the bike and you can see a slow drip coming from this.  The book said to replace it with a 47mm o-ring.  I thought this was the same part number as the o-ring that goes from the pump to the case, PN#: 91302-250-010, but it's not.  It looks like its a few millimeters too big.  I am also unsure if its supposed to be a square o-ring or if the old o-ring is just malformed from being so old.

Has anyone replaced this o-ring?  If yes, what are the dimensions?  Is it something I can take over to NAPA and have them match it up?  Is it a square or round o-ring?

Attached is a picture of the cover, highlighted in yellow.

Thanks!

[Maraakate]

It appears I may have answered my own question.  An older thread mentions part number 91305-426-003 originally for a GL1000 should work.  I will give the dealership a call tomorrow and once installed I will update if this is the right part.

[bryanj]

Yes it will work, 46x2 O ring.
Undo the cover screws with pump on engine using an impact driver

[trigger]

Much easier to replace a whole kit > https://www.ebay.co.uk/itm/Honda-CB550-4-FOUR-F1-F2-K0-K1-K2-K3-SOHC-oil-pump-O-ring-kit/164181515369?hash=item2639fb1c69:g:yAoAAOSwCMFZ6JUA

[bryanj]

Yup, but that kit is in the UK i know the seller who is super helpfull but you are still dealing with international postage so maybe easier to go the Honda dealer way even if not a lot cheaper

[DaveBarbier]

Contact member Elan. He puts together and sells oil pump rebuild kits with all o-rings included. Here’s a link to the whole kit but I bet he can send you just that one. But, maybe not a bad idea to have the whole kit in case the other seals go bad.


https://www.ebay.com/itm/163309915351

[Maraakate]

I already have the larger o-ring that goes to the pump to base and I also ordered the two smaller o-rings as well, but I am waiting for them to show up from partszilla (I learned really quickly my local dealer has better prices than partszilla oh well!).

@BryanJ: Yes, when I got the wrong o-ring I learned quickly that you must use the impact driver to get the cover off.  Thanks for mentioning it though.

[Maraakate]

Also, I see that both kits have the o-ring for the pressure relief valve.  Of course this is also a part that doesn't show up on the microfiche.  I can replace this too if someone has a part number for me.  Is there anything special I need to know about disassembling the relief valve?  I already have the two o-rings for the collars on their way.

I'm more of a "don't fix it if it ain't broke" kind of person.  However, I do understand that by replacing the o-ring on the cover the leak may move to another seal on this pump.  I'm OK with doing the o-rings that go to the case as I believe that should be easy to remove without many repercussions.  It's that relief valve that I am concerned about.  Especially when I have never done it before.

[bryanj]

In 40 odd years i never took a relief vavle cap off, leave it allone.

[Maraakate]

In 40 odd years i never took a relief vavle cap off, leave it allone.

I agree.  I will just do the outer cover, verify it is no longer leaking, check it again in a week and if new leaks appear in the back or from the pressure relief valve then I will follow up.  I don't like to disturb things that are not broken.  Especially o-rings/gaskets.  I've found as you've put a good few hundred miles on some old mystery bike (like mine, and it's been over 3000 miles now) the leaks that need fixed will show up, others you thought were an issue may disappear.  When you disturb things is when that seal is broken and now it must be replaced.

[trigger]

Yup, but that kit is in the UK i know the seller who is super helpfull but you are still dealing with international postage so maybe easier to go the Honda dealer way even if not a lot cheaper

Julie sends those upgraded kits out worldwide at a postage cost of £2.90 mate 

[bryanj]

Not the cost Trigger, seems from other comments that international mail into US is being held up at moment. Julie stocks a lot of good stuff and service is excellant but post offices are not good at present. I read that Japan post has sent nothing out at all for a while.

[trigger]

Not the cost Trigger, seems from other comments that international mail into US is being held up at moment. Julie stocks a lot of good stuff and service is excellant but post offices are not good at present. I read that Japan post has sent nothing out at all for a while.

I have not had any problems with post in or out. Packages get to Australia, New Zealand and the States quicker than any of the Scandinavian countries but, that has always been the case for some strange reason . My Yamiya orders have been coming through with UPS in less than a week to my door for the past 2 months.

[Maraakate]

Got the o-ring today from the dealer.  Swapped out the old one with the new one and it appears all is well, but we'll find out after a few rides if it decides to weep out of the other ares on the pump