I've got a Universal M3-20B with about 1,100 hours running time that has developed the unfortunate characteristic of occasionally ejecting its dipstick. The last time it got tangled up with the crank in addition to its usual tactic of spraying oil out the dipstick hole. The breather on the valve cover is not clogged so I'm a little mystified why the pressure is building up in the crankcase. This has happened twice in about the last 70 hours of running at 2500 rpm and I've found it loose on my daily inspections while cruising several more times. Other than that, the engine starts and runs very well with no unusual exhaust, oil consumption, or sounds. The rubber seal that holds the dipstick in place is in good condition and it requires moderately firm pressure to seat it. The last time this happened we took the oil pan off and saw nothing unusual at least so far as what tight spaces and an inspection mirror could reveal. So I give up. Does anyone have any thoughts?
Disappearing dipstick!
- Thread starter knothead
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Piston blowby causing pressure inside the crankcase and thus behind the dipstick. Its probably worse when the engine is cold and brought to high rpms before warming up. You'll need to do a compression test to confirm.. otherwise if the breather is clogged, that could do it.. but doubtful at the pressures you need to make to fire the entire dipstick out of the tube.
Or just get another dipstick. Just 'cuz it "seems" OK may not be so. What do you have to lose? If that works, you can put away the engine tear-down. 
My thoughts exactly! I've seen a lot of alternators and batteries replaced because of a corroded connection. My motto is, "Assume the worst if you want but always consider the easiest fix first". Thanks for reminding me. Hedging my bets, I'm going to also run the compression test that the previous poster mentioned and hope that the results aren't hideous enough to prevent sailing more and motoring less until the end of the season. Aren't we supposed to be doing that anyway? Isn't that why we practice "hipping up" the dink? Now if only the Admiral agrees.Or just get another dipstick. Just 'cuz it "seems" OK may not be so. What do you have to lose? If that works, you can put away the engine tear-down.
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