willy5572 Posted March 11, 2011 Report Share Posted March 11, 2011 Hi guys, just wondering if anyones got any advice, my sherco 290 (03) is pumping oil from the crankcase breather. I have replaced the crankcase seals but after a recent trial found i had lost all off the oil, topped it back up with 450ml and sure enough the same problem from the breather. could this be a fault with the crankcase bearing? or am i clutching at straws cos this bike has had nothing but problems with seals since i had it. any adivce would be gratfully recieved thanks Quote Link to comment Share on other sites More sharing options...
chewy Posted March 11, 2011 Report Share Posted March 11, 2011 could it be centre gasket..dodgy casting/machining crank halfs, does it suck and blow, Quote Link to comment Share on other sites More sharing options...
copemech Posted March 12, 2011 Report Share Posted March 12, 2011 (edited) I have never heard of this being anything but a seal problem. How old are they, and what brand? I doubt the bearings would be the issue unless they are terribly loose, being able to move the crankshaft up-down 1mm or so. Probably sound rough too. Another way to test for excess gearbox vent pressure would be to submerse the end of the tube in a cup of water and look for bubbles. Edited March 12, 2011 by copemech Quote Link to comment Share on other sites More sharing options...
lineaway Posted March 12, 2011 Report Share Posted March 12, 2011 I have never seen oil go out the breather unless over filled or upside down. Quote Link to comment Share on other sites More sharing options...
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