Twice now in the last month somthing in my engine has been going wrong. It keeps blowing the crankseal and drawing in tranny oil into the cylinder...The first time I didn't think much of it, but the second time has me wondering. What could be causing it to blow out like this? Could pressure from the case be getting out and pusing out the seal? Could it be the crankbearings?

Thanks
Chad

 

try to change the oil and oil filter. that might be the problem. because if to much stuff is in the oil filter it will block and create pressure and that could blow seals

 

no oil filter...2-stroke,

 

I think he is talking about his blaster, which don't use an oil filter.

If you crank bearings were shot, you would know it. A little play in the crank bearings is TOO much. You might try polishing the crank journal where the seal rides. It might be a little rough or uneven. Make sure your trans case vents aren't stopped up. If so it could build pressure which would be hard on the seal.

 

I had that problem with my old RM125 and it ended up that the crank was bent. It was going through the seals like candy, and when I split the case sure enough crank was bent... Hope its something simpler and cheaper for you!

 

The first time I had this problem, about 3 weeks ago, It would run fine in nutural but the minute you put it in gear you could hold it wide open and it would just bog and smoke really bad..At first i thought it was just the plug fouled. I took it to the dealer and sure enough the crank seal was tore right out of its place and was shreaded up into little pieces. I got it fixed and it ran perfect, up until last night. it is acting jsut like it did before when the seal went the first time but what I can't figure out is why...When we replaced the seal the first time, the crank and bearings all looked to be perfect..So that can't be it..

Alky, You mentioned that the breather could be blocked? Come to think about it Back before the seal went the first time I had re-routed the breather tube from under the hood to go under the seat to the airbox..Do you think maybe the weight or somthing of me on the seat is putting a kink in the tube and not allowing the air to pass? Could It build up enough preassure to blow the seal..twice?

 

It could be kinked. It can build up quite a bit of pressure. I have seen the trans output shaft (behind the front sprocket) blow out of its spot in the case. I think trans case pressure is a factor in that happening. I have never seen a crank seal shredded though.

 

It was tore up because once it came out of the bore it basically floated in the case and was ripped between the primary gear and the clutch.

 

I am surprised it even ran long enough after the seal came out to tear it up.