Topic: '82 CB650 - leaky oil pump

[papi_sosaa]

Hello all,

I've almost completed my build, just waiting on some parts. I rebuilt the engine last year and besides 1 small leak, the engine seems pretty healthy.

Just curious if anybody can give some insight as to why the oil pump is leaking here. Based on the diagram, I replaced o-ring's #12, #13, #14, and #15. Can those collars inside the oil passages be an issue? Are these pumps just finicky when installing?

Here's the video of it running:
https://www.reddit.com/r/HondaCB/comments/1khcb6o/comment/mr6kpim/?context=3

[bryanj]

The 400/500/550 can leak from the top cover held on by 3 bolts/screws as there is an O ring under it which is not listed seperately but is a 46x2 O ring.
I have never dissasembled a 650 pump so dont know if it is the same or not.
It is also not unknown for the pressure switch to leak through the screw holding the wire on

[papi_sosaa]

The 400/500/550 can leak from the top cover held on by 3 bolts/screws as there is an O ring under it which is not listed seperately but is a 46x2 O ring.
I have never dissasembled a 650 pump so dont know if it is the same or not.
It is also not unknown for the pressure switch to leak through the screw holding the wire on

There is no oil running down the oil pump from either the front plate or the pressure switch. It looks like it is only leaking from that passage.

[DaveBarbier]

There has been an ongoing misprint or mislabeling in the Honda parts diagram for forever. The #13 o-ring is noted as a 42mm x 2mm but it’s actually a 53mm x 3mm. The unlisted o-ring Bryanj mentioned is the 42mm x 2mm. What o-rings did you use to replace? If you followed the parts diagram that could be the source of your leak.

Check out my post on the 650 oil pump, it may be some use. http://forums.sohc4.net/index.php/topic,184610.100.html. I also keep that link in my signature as well.

I don’t sell the o-ring kits anymore though, mostly because I live in Sweden now and shipping to members in the US and Canada isn’t worth it for either side.

[DaveBarbier]

There has been an ongoing misprint or mislabeling in the Honda parts diagram for forever. The #13 o-ring is noted as a 42mm x 2mm but it’s actually a 53mm x 3mm. The unlisted o-ring Brian mentioned is the 42mm x 2mm. What o-rings did you use to replace? If you followed the parts diagram that could be the source of your leak.

Check out my post on the 650 oil pump, it may be some use. http://forums.sohc4.net/index.php/topic,184610.100.html. I also keep that link in my signature as well.

I don’t sell the o-ring kits anymore though, mostly because I live in Sweden now and shipping to members in the US and Canada isn’t worth it for either side.

Oh yeah, and note that in my post I have a picture of the diagram from the ‘79 not the ‘82. That’s why the numbers are different. Your #13 is the same as my #16.

[papi_sosaa]

There has been an ongoing misprint or mislabeling in the Honda parts diagram for forever. The #13 o-ring is noted as a 42mm x 2mm but it’s actually a 53mm x 3mm. The unlisted o-ring Brian mentioned is the 42mm x 2mm. What o-rings did you use to replace? If you followed the parts diagram that could be the source of your leak.

Check out my post on the 650 oil pump, it may be some use. http://forums.sohc4.net/index.php/topic,184610.100.html. I also keep that link in my signature as well.

I don’t sell the o-ring kits anymore though, mostly because I live in Sweden now and shipping to members in the US and Canada isn’t worth it for either side.

Part #13 in the diagram for my '82 650SC oil pump says it's a 46mm x 2mm o-ring. I looked up the diagram for the '79 650 and the o-ring listed as #16 says the same thing. The part number is different but the dimensions are the same. Is it actually 42mm or 46?

I replaced the o-rings last year with OEM rings but I didn't replace the o-ring behind the cover plate. I didn't know there was a part number for it.

[bryanj]

I dont think either are those sizes, as stated in a post about Honda quoted the wrong sizes for the O rings, also there is no part number for the one under the cover as it was never sold seperate, found the size for the 500/550 by carefull measurement and trial/error

[DaveBarbier]

There has been an ongoing misprint or mislabeling in the Honda parts diagram for forever. The #13 o-ring is noted as a 42mm x 2mm but it’s actually a 53mm x 3mm. The unlisted o-ring Brian mentioned is the 42mm x 2mm. What o-rings did you use to replace? If you followed the parts diagram that could be the source of your leak.

Check out my post on the 650 oil pump, it may be some use. http://forums.sohc4.net/index.php/topic,184610.100.html. I also keep that link in my signature as well.

I don’t sell the o-ring kits anymore though, mostly because I live in Sweden now and shipping to members in the US and Canada isn’t worth it for either side.

Part #13 in the diagram for my '82 650SC oil pump says it's a 46mm x 2mm o-ring. I looked up the diagram for the '79 650 and the o-ring listed as #16 says the same thing. The part number is different but the dimensions are the same. Is it actually 42mm or 46?

I replaced the o-rings last year with OEM rings but I didn't replace the o-ring behind the cover plate. I didn't know there was a part number for it.

Oh my mistake, I meant 46 not 42. But the issue still remains. The parts diagram is wrong for the o-ring size for the body of the oil pump to engine case. They say it's a 46mm x 2mm but it's actually a 53mm x 3mm. The 46mm x 2mm o-ring is actually for the oil pump cover plate which isn't marked on the diagram.

[DaveBarbier]

I dont think either are those sizes, as stated in a post about Honda quoted the wrong sizes for the O rings, also there is no part number for the one under the cover as it was never sold seperate, found the size for the 500/550 by carefull measurement and trial/error

Right, it was never sold separately but mine was leaking so that's when I found the size and came across that error.

[papi_sosaa]

There has been an ongoing misprint or mislabeling in the Honda parts diagram for forever. The #13 o-ring is noted as a 42mm x 2mm but it’s actually a 53mm x 3mm. The unlisted o-ring Brian mentioned is the 42mm x 2mm. What o-rings did you use to replace? If you followed the parts diagram that could be the source of your leak.

Check out my post on the 650 oil pump, it may be some use. http://forums.sohc4.net/index.php/topic,184610.100.html. I also keep that link in my signature as well.

I don’t sell the o-ring kits anymore though, mostly because I live in Sweden now and shipping to members in the US and Canada isn’t worth it for either side.

Part #13 in the diagram for my '82 650SC oil pump says it's a 46mm x 2mm o-ring. I looked up the diagram for the '79 650 and the o-ring listed as #16 says the same thing. The part number is different but the dimensions are the same. Is it actually 42mm or 46?

I replaced the o-rings last year with OEM rings but I didn't replace the o-ring behind the cover plate. I didn't know there was a part number for it.

Oh my mistake, I meant 46 not 42. But the issue still remains. The parts diagram is wrong for the o-ring size for the body of the oil pump to engine case. They say it's a 46mm x 2mm but it's actually a 53mm x 3mm. The 46mm x 2mm o-ring is actually for the oil pump cover plate which isn't marked on the diagram.

So in a bid to try and fix this again, I had ordered the 46x2 (#13), the x2 13.8x2.5 (#12), and 7x1.7 (#15) the other day.

After this conversation, I tried to order that 53x3 from McMaster-Carr but with what's going on in the States, they cancelled my order because they won't ship it to Canada.

Right now I'm trying to find an alternative way to get this o-ring.

[DaveBarbier]

There has been an ongoing misprint or mislabeling in the Honda parts diagram for forever. The #13 o-ring is noted as a 42mm x 2mm but it’s actually a 53mm x 3mm. The unlisted o-ring Brian mentioned is the 42mm x 2mm. What o-rings did you use to replace? If you followed the parts diagram that could be the source of your leak.

Check out my post on the 650 oil pump, it may be some use. http://forums.sohc4.net/index.php/topic,184610.100.html. I also keep that link in my signature as well.

I don’t sell the o-ring kits anymore though, mostly because I live in Sweden now and shipping to members in the US and Canada isn’t worth it for either side.

Part #13 in the diagram for my '82 650SC oil pump says it's a 46mm x 2mm o-ring. I looked up the diagram for the '79 650 and the o-ring listed as #16 says the same thing. The part number is different but the dimensions are the same. Is it actually 42mm or 46?

I replaced the o-rings last year with OEM rings but I didn't replace the o-ring behind the cover plate. I didn't know there was a part number for it.

Oh my mistake, I meant 46 not 42. But the issue still remains. The parts diagram is wrong for the o-ring size for the body of the oil pump to engine case. They say it's a 46mm x 2mm but it's actually a 53mm x 3mm. The 46mm x 2mm o-ring is actually for the oil pump cover plate which isn't marked on the diagram.

So in a bid to try and fix this again, I had ordered the 46x2 (#13), the x2 13.8x2.5 (#12), and 7x1.7 (#15) the other day.

After this conversation, I tried to order that 53x3 from McMaster-Carr but with what's going on in the States, they cancelled my order because they won't ship it to Canada.

Right now I'm trying to find an alternative way to get this o-ring.

First I’d try to figure out exactly where it’s leaking from, maybe you don’t need that o-ring. But if you do, search around. Maybe eBay? You’ll want a buna N (nitrile) for the material, or viton (FKM). Both will be heat and oil resistant. I prefer buna N because from my experience viton normally comes with a texture instead of smooth and it also has a higher shore hardness than buna N.

You could also first take off the oil pump and measure to be extra sure. If you lean the bike over to the right you won’t have to drain your oil.  You can see my post about the oring in my signature to see how much I leaned it over.

[papi_sosaa]

There has been an ongoing misprint or mislabeling in the Honda parts diagram for forever. The #13 o-ring is noted as a 42mm x 2mm but it’s actually a 53mm x 3mm. The unlisted o-ring Brian mentioned is the 42mm x 2mm. What o-rings did you use to replace? If you followed the parts diagram that could be the source of your leak.

Check out my post on the 650 oil pump, it may be some use. http://forums.sohc4.net/index.php/topic,184610.100.html. I also keep that link in my signature as well.

I don’t sell the o-ring kits anymore though, mostly because I live in Sweden now and shipping to members in the US and Canada isn’t worth it for either side.

Part #13 in the diagram for my '82 650SC oil pump says it's a 46mm x 2mm o-ring. I looked up the diagram for the '79 650 and the o-ring listed as #16 says the same thing. The part number is different but the dimensions are the same. Is it actually 42mm or 46?

I replaced the o-rings last year with OEM rings but I didn't replace the o-ring behind the cover plate. I didn't know there was a part number for it.

Oh my mistake, I meant 46 not 42. But the issue still remains. The parts diagram is wrong for the o-ring size for the body of the oil pump to engine case. They say it's a 46mm x 2mm but it's actually a 53mm x 3mm. The 46mm x 2mm o-ring is actually for the oil pump cover plate which isn't marked on the diagram.

So in a bid to try and fix this again, I had ordered the 46x2 (#13), the x2 13.8x2.5 (#12), and 7x1.7 (#15) the other day.

After this conversation, I tried to order that 53x3 from McMaster-Carr but with what's going on in the States, they cancelled my order because they won't ship it to Canada.

Right now I'm trying to find an alternative way to get this o-ring.

First I’d try to figure out exactly where it’s leaking from, maybe you don’t need that o-ring. But if you do, search around. Maybe eBay? You’ll want a buna N (nitrile) for the material, or viton (FKM). Both will be heat and oil resistant. I prefer buna N because from my experience viton normally comes with a texture instead of smooth and it also has a higher shore hardness than buna N.

You could also first take off the oil pump and measure to be extra sure. If you lean the bike over to the right you won’t have to drain your oil.  You can see my post about the oring in my signature to see how much I leaned it over.

I replaced these o-rings last year when I rebuilt the engine and I don't have an original to measure now. When I first noticed the leak after the rebuild, I took it apart and couldn't figure out if it was leaking from the smaller oil passage on the bottom of the pump or past the pump-to-block o-ring. If you're definitively saying that the pump-to-block o-ring is the wrong size in the catalog then I want to start there.

When I replaced the o-rings last year, I took off that front cover plate and just reinstalled it because it didn't show anything in the catalog. I already ordered a new 46x2 o-ring so I'll just put it there if it fits.

The oil pump assembly part number is the same between the '79 and the '82 models, if you're saying the pump-to-block o-ring was 53x3 for you then there's a very good chance it's going to be the same for me too.

[DaveBarbier]

There has been an ongoing misprint or mislabeling in the Honda parts diagram for forever. The #13 o-ring is noted as a 42mm x 2mm but it’s actually a 53mm x 3mm. The unlisted o-ring Brian mentioned is the 42mm x 2mm. What o-rings did you use to replace? If you followed the parts diagram that could be the source of your leak.

Check out my post on the 650 oil pump, it may be some use. http://forums.sohc4.net/index.php/topic,184610.100.html. I also keep that link in my signature as well.

I don’t sell the o-ring kits anymore though, mostly because I live in Sweden now and shipping to members in the US and Canada isn’t worth it for either side.

Part #13 in the diagram for my '82 650SC oil pump says it's a 46mm x 2mm o-ring. I looked up the diagram for the '79 650 and the o-ring listed as #16 says the same thing. The part number is different but the dimensions are the same. Is it actually 42mm or 46?

I replaced the o-rings last year with OEM rings but I didn't replace the o-ring behind the cover plate. I didn't know there was a part number for it.

Oh my mistake, I meant 46 not 42. But the issue still remains. The parts diagram is wrong for the o-ring size for the body of the oil pump to engine case. They say it's a 46mm x 2mm but it's actually a 53mm x 3mm. The 46mm x 2mm o-ring is actually for the oil pump cover plate which isn't marked on the diagram.

So in a bid to try and fix this again, I had ordered the 46x2 (#13), the x2 13.8x2.5 (#12), and 7x1.7 (#15) the other day.

After this conversation, I tried to order that 53x3 from McMaster-Carr but with what's going on in the States, they cancelled my order because they won't ship it to Canada.

Right now I'm trying to find an alternative way to get this o-ring.

First I’d try to figure out exactly where it’s leaking from, maybe you don’t need that o-ring. But if you do, search around. Maybe eBay? You’ll want a buna N (nitrile) for the material, or viton (FKM). Both will be heat and oil resistant. I prefer buna N because from my experience viton normally comes with a texture instead of smooth and it also has a higher shore hardness than buna N.

You could also first take off the oil pump and measure to be extra sure. If you lean the bike over to the right you won’t have to drain your oil.  You can see my post about the oring in my signature to see how much I leaned it over.

I replaced these o-rings last year when I rebuilt the engine and I don't have an original to measure now. When I first noticed the leak after the rebuild, I took it apart and couldn't figure out if it was leaking from the smaller oil passage on the bottom of the pump or past the pump-to-block o-ring. If you're definitively saying that the pump-to-block o-ring is the wrong size in the catalog then I want to start there.

When I replaced the o-rings last year, I took off that front cover plate and just reinstalled it because it didn't show anything in the catalog. I already ordered a new 46x2 o-ring so I'll just put it there if it fits.

The oil pump assembly part number is the same between the '79 and the '82 models, if you're saying the pump-to-block o-ring was 53x3 for you then there's a very good chance it's going to be the same for me too.

Yeah they use the same o-ring. I have a 79 and 82 650. I haven’t taken apart one of these oil pumps in a while but I trust my 5 year ago self from the post I made, haha. So I’d be very surprised if he was wrong. I’ve rebuilt both my oil pumps with that and sold a few kits to members back then. But would still love you to confirm when you can.

You could still take off the oil pump and measure the groove, that’s your best bet anyway. The o-rings will shrink and compress so measuring an old o-ring isn’t a great method.

[bryanj]

Thing is that the part number may well get you the correct size but the size quoted in the parts book is wrong

[papi_sosaa]

So in a bid to try and fix this again, I had ordered the 46x2 (#13), the x2 13.8x2.5 (#12), and 7x1.7 (#15) the other day.

After this conversation, I tried to order that 53x3 from McMaster-Carr but with what's going on in the States, they cancelled my order because they won't ship it to Canada.

Right now I'm trying to find an alternative way to get this o-ring.

First I’d try to figure out exactly where it’s leaking from, maybe you don’t need that o-ring. But if you do, search around. Maybe eBay? You’ll want a buna N (nitrile) for the material, or viton (FKM). Both will be heat and oil resistant. I prefer buna N because from my experience viton normally comes with a texture instead of smooth and it also has a higher shore hardness than buna N.

You could also first take off the oil pump and measure to be extra sure. If you lean the bike over to the right you won’t have to drain your oil.  You can see my post about the oring in my signature to see how much I leaned it over.

I replaced these o-rings last year when I rebuilt the engine and I don't have an original to measure now. When I first noticed the leak after the rebuild, I took it apart and couldn't figure out if it was leaking from the smaller oil passage on the bottom of the pump or past the pump-to-block o-ring. If you're definitively saying that the pump-to-block o-ring is the wrong size in the catalog then I want to start there.

When I replaced the o-rings last year, I took off that front cover plate and just reinstalled it because it didn't show anything in the catalog. I already ordered a new 46x2 o-ring so I'll just put it there if it fits.

The oil pump assembly part number is the same between the '79 and the '82 models, if you're saying the pump-to-block o-ring was 53x3 for you then there's a very good chance it's going to be the same for me too.

Yeah they use the same o-ring. I have a 79 and 82 650. I haven’t taken apart one of these oil pumps in a while but I trust my 5 year ago self from the post I made, haha. So I’d be very surprised if he was wrong. I’ve rebuilt both my oil pumps with that and sold a few kits to members back then. But would still love you to confirm when you can.

You could still take off the oil pump and measure the groove, that’s your best bet anyway. The o-rings will shrink and compress so measuring an old o-ring isn’t a great method.

I managed to get an order through with McMaster-Carr by shipping it to my friends business I'll wait for all the o-rings to come in and then mess around with the pump.

I think I'm going to get this McMaster order before I get the o-rings I had ordered from some Honda parts shop in Quebec haha.

Hopefully it won't leak and then I'll come back with a good update. Appreciate the help so far.

[DaveBarbier]

Thing is that the part number may well get you the correct size but the size quoted in the parts book is wrong

Good point, I don’t recall if I started with an OEM o-ring or not. 

[papi_sosaa]

So I got a little impatient waiting for these OEM o-rings to come in, the order I placed contains an item on back order unrelated to the o-rings and they don't want to ship it until June 4th when all the parts are in stock. Not happy with this parts supplier, just found out I could order OEM parts through Fortnine so I'm going to start doing that from now on.

The o-rings I currently have in the oil pump are OEM and practically brand new so I just went ahead and pulled the oil pump, moved the 42mm o-ring to behind that front cover, and then placed the 53mm o-ring in the pump-to-block grove, ran the engine, and unfortunately I am still leaking in the same spot.

I don't know if it's as bad yet so I'm going to keep heat cycling it a few times to see if it seals itself. Got my clutch cable issue sorted out, mounted the chain, and bled the front brakes, just waiting on throttle cables so I can finally take it for the first initial test ride.

[Jan187]

I just fixed my '81 650C sohc oil pump leak last weekend.
I used seals from a assortment box i had laying around.
It was the smallest on the top who was leaking, this is the pressure channel.
Replaced all of them, I just put in whatever seal fitted, they were a bit thicker than originals but compressed well into their grooves.

[papi_sosaa]

After putting some heat cycles through the engine, I can confirm that the oil pump is no longer leaking. That 53x3 o-ring did the trick.

Appreciate the help!

[DaveBarbier]

After putting some heat cycles through the engine, I can confirm that the oil pump is no longer leaking. That 53x3 o-ring did the trick.

Appreciate the help!

Glad it’s working. Odd that you say heat cycles would have cured it. A properly compressed o-ring will seal in the cold or hot. But either way, good that it’s sealed and you can move on. Thanks for the update.