Any idea what is causing this leak - 4 wheeler

[batoncolle]

Previously it was leaking along the seam in that area just behind the yellow circle and the stator cover gasket was replaced. Now it's leaking from the red circled area. Also it only leaks when the engine is running in both cases.

 

[StuP]

Crank oil seal I'd think.

 

[atljetmech]

You stating that it is a dynamic leak only has me thinking you need to check/clean crankcase breather.
While running and building crankcase pressure it will leak at path of least resistance.

 

[batoncolle]

Crank oil seal I'd think.

First let me just say that when it comes to cracking open anything engine related, I'm a complete novice so I may ask a stupid question.

When I do a search for crank oil seal, I get engine oil seal kit and crankshaft oil seal. Also are you talking about the rubber seal visible in the center of the pic, or would it behind that casing?

 

[41mag]

You stating that it is a dynamic leak only has me thinking you need to check/clean crankcase breather.
While running and building crankcase pressure it will leak at path of least resistance.

Just about what I was thinking - they have to breath

 

[batoncolle]

You stating that it is a dynamic leak only has me thinking you need to check/clean crankcase breather.
While running and building crankcase pressure it will leak at path of least resistance.

Is that a breather hose or within the crankcase? Here is a pic of the rear.

 

[StuP]

First let me just say that when it comes to cracking open anything engine related, I'm a complete novice so I may ask a stupid question.

When I do a search for crank oil seal, I get engine oil seal kit and crankshaft oil seal. Also are you talking about the rubber seal visible in the center of the pic, or would it behind that casing?

I'd really need to look at the service manual to see what seals would be needed. Some are easy to change, others need a fair bit of dissasembly.

 

[geezer]

It appears to me that that seal is easy to replace…I agree with the Airplane mechanic in that crankcase pressure might be overriding the seals ability to seal… look into the venting system, and know that the seal has a part number very visible on it…

 

[renagadeinjun]

Google is your friend ..................

 

[atljetmech]

Is that a breather hose or within the crankcase? Here is a pic of the rear.

I don't know your particular application but the hose/tube is typically:
Located at the top of the crankcase, may or may not have some type of one way check valve installed, might be routed towards bottom of engine,
And terminates to nothing (ie...vent).
With what you stated (leaks only when running) I would just verify cc vent is clean and venting before randomly changing gaskets and seals.