2 cyl. Onan

cuby

Member
I use my skid loader, next day after sitting overnihgt I check engine oil and oil is way up on the stick. I recheck, oil level is where it is suppose to be. I have also noticed a oil leak which is not coming from crankshaft seal. Anyone experience this? Could this be a cause of dirty crankcase breather?
 
The oil working it's way up the dipstick tube is an Onan quirk, I have a couple in DEERE 318 garden tractors that do the same thing, probably related to the O-ring on the dipstick cap not sealing 100% when the engine is hot.

Once you pull the dipstick and "break the suction" holding the oil elevated in the tube it drops to crankcase level and reinserting the dipstick to take another reading will give the correct level on the 'stick.

Pretty tough to diagnose your other problem, the oil leak, remotely, though.
 
Need to know what Onan you have. But yes a bad breather valve. Can cause that problem. Or the breather pad needs cleaning.
 
Thanks to all who responded. I will clean the breather and see if that might make a difference.
 
On the oil leak, check the filter mount, often a source of leaks. As to the dipstick level, It's actually due to the dipstick seal doing a good job. Dipstick tube bottom is below the oil level normally so with No air leak in or out, when the engine cools there is a vacuum in the tube above the oil level. Oil rises into the tube.

The crankcase breather does not vent air into the crankcase, only pressure out.
 
Ever saw the trick where a candle is placed under an inverted jar in a bowl of water? Same effect on any dipstick tube with a good seal. The effect also is helped some by the heat given off by the oil and parts building pressure like a pressure cooker inside of the crankcase.
 

On one of my p218gs the dipstick tube rubber Pringles sleeve going into the crankcase was so dry and brittle it not only cracked in half it was like hard plastic and I had to carefully cut it off the tube and scrape. I replaced with cummins oring sleeve and sealed the leak up. 40 year old rubber just dried up!
 

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