Help..520 leaking around countershaft

[Greg]

I've got a leak around my countershaft sprocket on my 2000 520exc. What is involved in changing that seal. Is this anything anyone else has seen on 520's?

 

[Person8]

That's a common side effect of running the chain too tight. Do a search in this forum for posts dealing with chain tension. As far as the seal goes, I believe you can just pop the old one out and press a new one in.

Larry

 

[DanS]

A spring puller can be used to pull the the old seal it just takes a little tugging. I seated the new one with a socket that was the same size. Check the bushing that goes over the shaft and make sure it is not grooved. If it is replace it too.

 

[DEGBERT]

Also, put in a new o-ring that goes behind the bushing.

 

[Shaw520]

If you recently changed your counter shaft sprocket, this could be your problem, some (many) of the aftermarket cs sprockets are not wide enough to hold pressure on the seal, and you WILL develope a leak. Check to make sure the 17mm nut is tightening down on the spring washer.

 

[endoquest]

Greg, remove the 17mm bolt and closely inspect the spring washer. I changed my seal, collar and o-ring and it still leaked. The culprit was the two-dollar spring washer(it had flattened out). If that washer isn't applying pressure to the sprocket and collar, the o-ring will not hold back oil. Very simple fix.

 

[marktm520]

If you are running an aftermarket sprocket, take it off and go to a machine shop that works on engine heads. Get a valve shim that will fit over the countershaft sprocket, install between the sprocket and seal. Fixed my leak since I was running a too thin aftermarket sprocket.