no oil pressure

by Andy LaVasser in General Tech Discussion 6 years ago

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Re: no oil pressure

by Andy LaVasser » 6 years ago

Andy LaVasser

2 3 0

CAN NOT FIND any leaks. lines and cooler seem clear. going to purge the system. if the top plugs are removed and system purged, what, if any, oil pressure would you expect when prop is spun? a manual gauge will replace the oil sender.

any concerns regarding lifters etc?

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Re: no oil pressure

by Bill Hertzel » 6 years ago

Bill Hertzel

13 1.95k 7.97k

The lifters naturally bleed down every time the engine stops and refill after each start.
The lifters will take care of themselves.

If you can muster one revolution of the Propeller per second, you should see ~20 psi after a dozen turns or so.

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
Clicking the "Thank You" is Always Appreciated by Everyone.

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Re: no oil pressure

by Roger Lee » 6 years ago

Roger Lee

126 5.14k 4.62k

When I do an oil purge with the top plugs out I wear a pair of leather welding gloves to cushion my hand and I can turn the prop approximately 1 rev per second. (Maybe not that fast towards the end. :)) I usually see about 55 psi. I rotate the prop about 80-90 turns. Then I call the medics for some oxygen LOL. Then I spin the prop like that again. I'm paranoid what can I say, but I never have a soft lifter and I make sure I do a good job. I don't like the alternative consequences. :)

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

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Re: no oil pressure

by James Stroud » 6 years ago

James Stroud

1 8 0

Roger, why not just use the starter to spin the motor? With the upper plugs out the engine will not start and the you can monitor the oil pressure from the cockpit.

Thanks,
Jim

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Re: no oil pressure

by Bill Hertzel » 6 years ago

Bill Hertzel

13 1.95k 7.97k

With the Plugs out, there will not be any pressure in the cylinders.
Without cylinder pressure, there will not be any cylinder Blow-By to pressurize the crankcase.
This means that None of the Oil in the Crankcase is going to be returned to the Oil Tank.
After about 30 or so revolutions of the prop, you are going to be Out of Oil and pumping air.
This defeats the whole purpose of this exercise.

If you are going to turn the engine with the plugs out to make it easier, you will need to ensure that the oil is getting back to the tank.
Either limit the cranking to 2 dozen turns before reinstalling the plugs, Or externally pressurize the crankcase.

You can pressurize the crankcase through the bolt hole near the #2 Cylinder used to lock the crankshaft.
Fabricate an 8mm stud (Plastic preferred) with a hole drilled down its center.
Screw this bolt into the crankshaft locking hole and slip a piece of hose over the bolt.
Blowing low-pressure air (<5psi) into the hose will pressurize the crankcase and return any Oil back to the Oil Tank.
You should hear the air and oil entering the oil Tank as evidenced by the Gurgling Sound in the Oil tank.

There is a strong temptation to blow into this hose using lung pressure.
This will work, but it also introduces extremely humid air into the crankcase. Not Good!
Resist the temptation by using regulated low-pressure shop air (<5psi) or a very short blast of the air gun whenever the gurgling stops.

CaseVent.jpg (You do not have access to download this file.)

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
Clicking the "Thank You" is Always Appreciated by Everyone.

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