eddystone
Well-Known Member
Just curious. Chartered a Jeanneau recently with Yanmar engine. Whenever I removed dipstick to check oil it was completely dry but when re-inserted to check level showed correct level. How do they do that?
Makes sense.I expect the dipstick is in a tube that goes almost to the bottom of the sump. to prevent the 'blade' flailing around and coming into contact with reciprocating parts.
The dipstick seals the top of the tube and when the engine is running, oil in the bottom of the tube is extracted, leaving the tube empty. When you remove the stick and replace it, the oil in the sump can seep back to indicate the level in the whole sump.
It may be an accidental piece of design, but the two-stage process means you can't misread the stick at a single reading if it has been splashed with oil.
And my 3GM.Makes sense.
My 3JH series engine dipstick behaves as described in the OP.
Ah that explains it. Don’t know what model it was 29hp. I only have experience of VP and BetaI expect the dipstick is in a tube that goes almost to the bottom of the sump. to prevent the 'blade' flailing around and coming into contact with reciprocating parts.
The dipstick seals the top of the tube and when the engine is running, oil in the bottom of the tube is extracted, leaving the tube empty. When you remove the stick and replace it, the oil in the sump can seep back to indicate the level in the whole sump.
It may be an accidental piece of design, but the two-stage process means you can't misread the stick at a single reading if it has been splashed with oil.
+1Which engine. My 4JH series engine always shows oil when I pull the dipstick.