Crankcase ventilation ?

[pmcdonald]

I have a 2003 RT that continues to leak oil from the filler plug. I have replaced the rubber gasket and plastic assembly that the plug locks into. The shop has done the same thing on a couple occassions. Yesterday I noticed something different. After I put another rubber gasket on and made sure it was snug I tried to start the bike. It coughed and sounded like the timing was off as it turned over. After about 15 seconds I tried again and it sounded like the seal on the plug was releasing pressure. Once that was happening the motor ran fine. Of course it was leaking oil again. My question is this - Is this possible? Is there a breather tube that could be blocked or kinked that could be causing this?

[ShovelStrokeEd]

Yes, there is such a tube. It runs from the rear of the crankcase to the air box.

 

The boxer motor suffers from huge changes in crankcase volume. As such, there is a whole bunch of air moving around inside the engine at any moment. This results in lots of variation in pressure. The vent tube does not do very much to relieve this, its function is more to handle increased pressure due to blowby.

 

I would guess that something is wrong with the sealing surface on your rocker cover. Why not try a different one. With a total of around 200K miles on 4 oil heads, I never had a filler plug leak on me.

 

Take note that there are two O-rings involved here, one under the head of the plug and another at the base of the filler pipe. Has that been changed as well? You make no mention of it. Note items 5 and 6 in the attachment.

[pmcdonald]

I forgot about the second O-Ring. It doesn't look like the oil is coming from there but I will check it out. Thanks Ed.