SOHC.co.uk Forums > CB750
Crankcase seal leaking
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.
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