Topic: How are you guys able to keep your 550 oil pans from leaking?

[psykod]

I've done everything I can think of to stop the oil leak from the mating surface of my CB550 oil pan.  It's got a new o-ring, and the surface was clean and defect free when I installed it.  All bolts were torqued to spec.  

When I first put it back together it didn't leak, but now after a few hundred miles, it's leaking again.  I can see where the oil is running down from all along the left side at the mating area, especially when the bike is on it's kick stand (as opposed to its center stand).

Could it be the o-rings from the gasket kits are not quite the right size and are shrinking due to the heat?

My next step is to take the pan to a machine shop and have the surface milled flat.

I was also thinking of buying a used pan on eBay and having the o-ring groove filled, the surface machined flat, then making a custom gasket.

If anyone has had problems with their own oil pans leaking and come up with a fix, I would like to hear it.

[HondaMan]

I have found that many gasket kits (for the 750, so I suspect the 500/550 also) are coming with undersized (thickness) O-rings lately. This problem seems to stem from misunderstandings about Honda's parts descriptions. For example, if you look up the O-ring size for the fuel tees for a CB750K1-K6, the fiche show a size 7.9x1.9mm O-ring. This is not a standard size: it is the MINIMUM size that will seal the union. This is almost universally true with Honda's stated O-ring sizes in their parts catalogs, and recent newcomer vendors to the gasket markets are coming up with wrong sizes.

I have given up on all but Vesrah's kits, where O-rings are involved: I just go to a local seal store and get the right ones. In the above example, the standard O-ring is size 8x2, which fits perfectly. There are also several situations where the online parts fiche are simply wrong, like for the 550 O-ring that seals the oil pump. Last summer, I bought a bag of the right size ones (they are NOT 47mm ID, more like 58mm), but I'll be danged if I can find it: two other SOHC4-ers are looking for these from me. I need another 550 oil pump so I can measure it again. 

[luap]

also had the same problem, first time though i pinched the o ring, second o ring still leaked so 3rd o ring i used i filled the groove with black gasket sealer then put the o ring in, hasnt leaked since

[Accolay]

Mine leaks because I need a new pan. A PO botched the drain plug so bad they had to tap with a big SAE bolt.

[steam-powered man]

check the "O" rings that attach your oil pump to the case.  had a similar leak last week, turned out the o-rings were actually flat.  found 'em in a hardware store for $.80.

inside the left cover is a small recessed area with a drilled hole.  the oil will collect here when on the side stand, and run out the drilled hole when brought upright.     

[HondaMan]

check the "O" rings that attach your oil pump to the case.  had a similar leak last week, turned out the o-rings were actually flat.  found 'em in a hardware store for $.80.

inside the left cover is a small recessed area with a drilled hole.  the oil will collect here when on the side stand, and run out the drilled hole when brought upright.     

Very common: I've seen this one every 550 that has come here in the last 3 years.

[psykod]

check the "O" rings that attach your oil pump to the case.  had a similar leak last week, turned out the o-rings were actually flat.  found 'em in a hardware store for $.80.

inside the left cover is a small recessed area with a drilled hole.  the oil will collect here when on the side stand, and run out the drilled hole when brought upright.      

I used to have this problem as well.  I just considered it routine to replace those o-rings every month or two.  However, this time it's definitely coming from the oil pan mating surface (as verified with the standard baby powder test).  

Does anyone know the o-ring size for the oil pan?  It's just listed in the parts manual as:

GASKET, OIL PAN
11398-426-000

[steam-powered man]

ah, the baby powder trick.  clean off, sprinkle w/powder and look for the wet spot.  reminds me of my 2nd wife. 

[HawaiiMike]

I used to have this problem as well.  I just considered it routine to replace those o-rings every month or two.  However, this time it's definitely coming from the oil pan mating surface (as verified with the standard baby powder test).  

Does anyone know the o-ring size for the oil pan?  It's just listed in the parts manual as:

GASKET, OIL PAN
11398-426-000

Maybe it's the oil pan?  Why not install another pan and see if that solves the problem?

[Godffery]

I have found that many gasket kits (for the 750, so I suspect the 500/550 also) are coming with undersized (thickness) O-rings lately. This problem seems to stem from misunderstandings about Honda's parts descriptions. For example, if you look up the O-ring size for the fuel tees for a CB750K1-K6, the fiche show a size 7.9x1.9mm O-ring. This is not a standard size: it is the MINIMUM size that will seal the union. This is almost universally true with Honda's stated O-ring sizes in their parts catalogs, and recent newcomer vendors to the gasket markets are coming up with wrong sizes.

I have given up on all but Vesrah's kits, where O-rings are involved: I just go to a local seal store and get the right ones. In the above example, the standard O-ring is size 8x2, which fits perfectly. There are also several situations where the online parts fiche are simply wrong, like for the 550 O-ring that seals the oil pump. Last summer, I bought a bag of the right size ones (they are NOT 47mm ID, more like 58mm), but I'll be danged if I can find it: two other SOHC4-ers are looking for these from me. I need another 550 oil pump so I can measure it again. 

I may be looking for that o-Ring from you as well... Have you got your hands on a 550 pump yet? If not I can send you one in exchange for the proper o-Ring.
BUT...
I believe I may have deeper issues regarding too much pressure, here's my recent post:
http://forums.sohc4.net/index.php?topic=73709.0

[crazypj]

You have checked it's flat?
 overtightening will make it leak worse

[HondaMan]

I have found that many gasket kits (for the 750, so I suspect the 500/550 also) are coming with undersized (thickness) O-rings lately. This problem seems to stem from misunderstandings about Honda's parts descriptions. For example, if you look up the O-ring size for the fuel tees for a CB750K1-K6, the fiche show a size 7.9x1.9mm O-ring. This is not a standard size: it is the MINIMUM size that will seal the union. This is almost universally true with Honda's stated O-ring sizes in their parts catalogs, and recent newcomer vendors to the gasket markets are coming up with wrong sizes.

I have given up on all but Vesrah's kits, where O-rings are involved: I just go to a local seal store and get the right ones. In the above example, the standard O-ring is size 8x2, which fits perfectly. There are also several situations where the online parts fiche are simply wrong, like for the 550 O-ring that seals the oil pump. Last summer, I bought a bag of the right size ones (they are NOT 47mm ID, more like 58mm), but I'll be danged if I can find it: two other SOHC4-ers are looking for these from me. I need another 550 oil pump so I can measure it again. 

I may be looking for that o-Ring from you as well... Have you got your hands on a 550 pump yet? If not I can send you one in exchange for the proper o-Ring.
BUT...
I believe I may have deeper issues regarding too much pressure, here's my recent post:
http://forums.sohc4.net/index.php?topic=73709.0

I'd be glad to trade: send me the pump, I'll remeasure the thingy and send one back to you with the pump. It's not like they are expensive: the parts lists are just wrong. 
PM me for my address?

[lordwhimsey]

I just measured an old 550 oil pump O-ring and it looks like:
Cross Section: 3mm
Inside Diameter: 52mm
Outside Diameter: 58mm
It's a little flattened so I maybe wrong.

It's £3.90 for a pack of two from http://simplybearings.co.uk so I'll order some and see how they work.

[psykod]

Just a quick follow up.  

I filled the o-ring groove of the oil pan with some of that high temperature epoxy for metal and had the surface milled flat by a local machine shop.  Cost more than buying a replacement pan on ebay (which I did as well in case the epoxy fix didn't work).  I used liquid gasket maker for the gasket.

Now my bike is dry as a bone.  Not a leak in sight.  I've gotten so used to seeing a puddle of oil under my bike, I don't know what I'm going to do with myself now!  

[crazypj]

Guess it wasn't flat then?