Oil migrating from engine to trans.

My 06 finally developed the deal where oil migrates from the trans to the engine a few weeks ago.  I replaced the crankshaft and balancer seals and it fixed this migration direction but NOW it goes from the engine to the trans... I used OEM seals and seated the crank seal flush and not in too far. The balancer seal was easy enough so I think I got that one right also but I did not apply any grease to the outer edge first. Could that cause engine oil to migrate to the trans? should I try that one again or is it more likely another seal somewhere?


Anybody been through this? 

Check the head vent hoses for pinching (might want to temporary disconnect the lower part and run with a small air filter on what's left)

Check that the head vent hose drain deal by the bottom of the carb is empty

Did you put the crank seal correct side out?  (metal side out)

Vent tube is clear. Wife thought I was nuts on the ground blowing into it...(oil cap removed) Crank seal is in correctly. I drain that brown liquid from head vent regularly. Thanks for the reply. I've been PMing with a member who suggested piston blow by over pressurizing the case. It was totally due for a top end and now I have the parts. Going to start with that then work my way down inspecting if needed.  

Yea I can't think of anything else but the new piston and cleaning up the jug.  Good luck!


I am running in to the same problem, engine oil migrating to the tranny , just want to check back and see how you resolved the issue. I am going to replace the crank seal for sure and possibly balancer seal since I am in there. Any knowledge would be helpful..


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