rjr 0 #1 Posted March 21, 2011 I started up the other day without the dipstick in place. I was amazed at the pressure coming out the hole. I am guessing that this is not a normal condition but the motor runs pretty well. Any thoughts would be appreciated Share this post Link to post Share on other sites
Kai Thomsen 17 #2 Posted March 21, 2011 That is all normal. When the engine is running without the dipstick in place, the piston moves a lot of air in and out of the engine. Share this post Link to post Share on other sites
JC 1965 1,532 #3 Posted March 22, 2011 :thumbs: I think that's normal. Share this post Link to post Share on other sites
sorekiwi 761 #5 Posted March 22, 2011 When the dipstick is in place, the positive pressure is vented through a flapper (one way) valve in the breather. What you are feeling is pressure in the crankcase being created by the piston moving down the bore. When the dipstick is in place, and the breather is operating correctly there should actually be negative pressure (a vacuum) in the crankcase. There is a section in the Kohler manual describing how to check crankcase vacuum. Share this post Link to post Share on other sites
