air comming out the sprocket???

[44oEX]

my friends 300ex has some problems, I think
If you start the motor and push on the front sprocket ( push it in )
there is air comming out the seal. no oil or anything just air. if you pull on the sprocket it stops.

It that normal??? I was thinking the seal was just shot but then there would be oil comming out to right???

I told him as long as there was no oil he didn't have anything to worry about. Cause if oil can't come out there is nothing that can go in.

What do you think?

[2004TRX450R]

I'd say he needs a new seal. But if there is a lot of play in the shaft then he may have other problems internally. If there is air comming out then oil will come out too. If the oil is just to low from leaking out or something then it wouldn't come out until is starts moveing where it will then splash oil up around the seal. Or it might just be way to low on oil so it isn't leaking out.

[44oEX]

no, the oil level is good and it's ben that way for a little time know. The oil has never came out the seal. ever.

[mustang93]

could be blow by maybe bad rings?

[Aceman]

Crankcases always need to vent. In your case I would check the vent tube coming off the top of the head and make sure it is not plugged or restricted. There's no reason for it venting through the seal unless the seal is shot or the breather hose is plugged up above.