Crankcase seal leaking

[Blasta]

Hi Guys,
My K4 has developed a leak from the crankcase seal behind the ignition. Can I replace that seal without splitting the cases?
Thanks

[Trigger]

Simple answer is nope. The seal is rubber over metal and has a lip that sits in a groove in the case. How bad is the leak ? I have never seen these leak on the contact to the case, only on the ID of the seal to the crank. it will have to be the big engine out.

[Blasta]

The leak is bad enough that I want to fix it, and I think it is leaking from the seal to the crank.

[Trigger]

The leak is bad enough that I want to fix it, and I think it is leaking from the seal to the crank.

While you have it apart, change all the engine seals, they do go hard over time 

[Blasta]

I will replace all the seals while I'm at it, but I'm still a bit confused.

I bought a seal kit in advance. Here's 2 pics of it, one from each side;
[ Guests cannot view attachments ] [ Guests cannot view attachments ]

And here's the seal in the bike.
[ Guests cannot view attachments ]

The seal appears to have no lips or ridges or anything on the outside surface. The seal in the bike is flush with the casings and they don't seem to be have any lip or anything holding the seal in. I looked in the manual I have and I can't see what's holding the seal in. 

After checking all that I thought the seal would come straight out and had a go, didn't matter if I damaged it it was already leaking and coming out one way or another. You can see some damage to it in the pic.

So, I still don't understand why it won't just come straight out. Can someone explain what holds the seal in?

[ka-ja]

Hi,
     They usually have a rounded "lip" running round the outside diameter that that sits in a groove machined in the crankcase seal housing and trapped in place when everything is bolted up, yours look like standard oil seals.
                       https://www.davidsilverspares.co.uk/graphics/parts/91201300003P_large.jpg

[Blasta]

OK, I see now. They must have sent me the wrong seal eventhough it has the correct part number on the bag.

[Rob62]

Put it in and see if it works... if it does, all well and good.

[Blasta]

Yeah I think I will, maybe with a tiny smear of sealant around the outside edge.
Now I just have to get the old one out. Any ideas?

[Nurse Julie]

Put it in and see if it works... if it does, all well and good.

How can it work?. It won't be sealed, it will just be a seal in a hole with nothing clamping it in there, ie, the casings.

[Rob62]

Not all lip-seals are locked in place, most just press in.... so long as its the correct size and material...

[Nurse Julie]

Agree, but I think Blasta will find that this seal is locked in place. Also, the only, non bodge way of removal is by splitting the crank cases and the same goes for insertion.

[Moorey]

That's how 99.9% of seals work by relying on a tight fit. Very few have a locating lip. Its purpose will be to ensure correct placement when building the engine.

[Moorey]

If its only a rubber lip I would expect to be able to get it out and fit a standard seal. Just make sure it is the same thickness and note how far the original seal is in. If need be make some sort of tapered seal installation tool to make sure you don't damage the lip seal that rides on the crank. As already said you have nothing to lose and everything to gain.
Certainly easier than pulling the engine and stripping, never mind the costs involved.
What I will say is the end of the crank doesn't look very happy and there could oxidisation on the crank where the seal sits. But that will be revealed when you get the seal out.

[K2-K6]

I'd follow the initial advice of dismantling it to change seals,  you really don't want to make it worse by risk of compromising the surfaces or the new seal.

But if you really want to remove it in situ then some do it by drilling and using self tapping screws in the face of the seal. Another is to drill two holes opossite each other and putting an Allen key small end into each so you can get a straight pull on them,  put mole grips on the Allen keys and use something like a slide hammer to drift it out.

In clamped cases like this application the steel internal and rubber coating is usually getting close to an interference fit in the cases,  that generally makes them very reluctant to come out. And hard to get replacement in without damage to it's structure. You'd need something like a flat faced drift with hollow centre to clear the crank.

As moorey points out,  it looks like the original seal may be compromised by corrosion of these crank surface.

Blocked crankcase breathers wouldn't help it either,  so worth looking at.