Oil weeping past new seal - nightmare


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Appreciate the help so far, thanks.

My latest problem with this recent project is a very small oil leak through the crankshaft oil seal into the alternator housing, it is seeping past the new oil seal lip, not from the oil seal housing.

I don’t know what has caused it, I had new con rods fitted so the crankshaft has been apart, but the alignment was checked by 2 independent companies, prior to installing, the seal is new and fitted correctly.

I seem to have 2 options, either live with the leak or change the seal?

Has anyone changed this seal before with the engine in situ and if so can you please advise on the best way to do it.

(Xs650 A/B 447 engine)

Regards Nick
The seal on the left side of the crank can be replaced without removing the engine. All you need to do is remove the side cover and alternator, rotor + stator. You will of course require an extractor to pull the rotor off the crank taper. The next trick is to remove the old seal. I have done this before using the "screw" method where you drill a small hole in the seal's metal body and then screw in a wood screw to use as a puller. The following video demonstrates this method:

Be warned: You must be very careful drilling the seal so as not to damage the crankshaft surface. The hole needs to be drilled through the metal reinforcing which lies towards the outer edge of the seal. I used a 2.5mm drill. Also, the video makes the seal extraction look very easy. It requires a little more force with the original XS650 seal because it has a rubber rib/bead moulded on the outer surface of the seal - the seal in the video is completely smooth. Below is a pushrod seal which illustrates the rib/bead that runs centrally around the outer surface. I think most replacement crank seals do not have the rib/bead so are easier to push back in.


When refitting the crank seal, or the pushrod seal, the process is much easier if you use a deburring tool to remove the very sharp edge on the seal housing.

I have used this method but be very careful not to damage the crankshaft's surface especially when drilling. A safer alternative to drilling may be to use a small seal extraction lever - Perhaps someone can recommend such a tool?
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For the Sprocket seal
I have used a piece of bicycle spoke as tool to pull out the seal. 2 or 3 times
I make a 90 degree perhaps a little less Like a small L at the end. so it grabs behind the seal
After removing some of the seal I push the Spoke in flat and then turn it 90 degrees
so the L is behind the seal
Use a pliers to yank and pull.
The spoke is stainless so it is a bit stronger
I managed to buy an oil seal yesterday locally for £2.89, the removal of the old oil seal was easy I used the drill and screw method as given by Paul, the only difference being as the seal was in so tight I needed 3 drill holes and screws. I could not believe it when it eventually just popped out, fitting the new seal was easy, I used a little Wellseal round the outside to aid sealing and just gently tapped it home.

Fingers crossed it holds oil and the problem is solved.