Thread: Is it possible...

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Is it possible for fuel from a mechancal fuel pump to leak into the engines oil around the plunger lever?

Yep, if the diaphragm ruptures. The actuating lever of a mechanical pump rides on an eccentric on the camshaft, which is inside the oil gallery.

I know the pump puts out to much pressure 10psi. But there has to be fuel comeing from more then just in the carb.

The leakage from a ruptured fuel pump diaphram will occur mainly when the engine is running,,,what ever pressure is left over between the pump and the carb will bleed off slowly,,,,how much fuel are we talking about here?? (knowing that no amount of fuel in the oil is a good thing),,,mechanical fuel pumps can go to 14lbs when they are in good condition,,,the pressure is only regulated when the motor is running via your fuel bowl floats and needles.
When the engine is off there would have to be quite a bit of pressure in the tank to push the fuel past the diaphram.
You can run a test for yourself by disconnecting the fuel line supply to the carb and have it run into a glass mason jar,,then turn your motor over with the key,,then observe the fuel coming into the mason jar,,,if you see lots of air bubbles (airiated fuel) then you probably have a cracked diaphram.

back when, chev. was bad about the mechancal fuel pump going bad and filling the oil pan full of gas. the last time it happened to me i was on a trip in a 1956 chev., 265 and the gas and oil started coming out of the dip stick tube. the motor was full of gas, but the motor ran great. put a pump on ,changed the oil and filter and the moter ran fine. it was clean inside though.

the engine is out of my truck now.

I would guess 1 litre of quart of fuel in the oil. there was no slipperyness left.

engine only lasted 62km. siezed it.

Originally posted by POWER2BURN
the engine is out of my truck now.

I would guess 1 litre of quart of fuel in the oil. there was no slipperyness left.

engine only lasted 62km. siezed it.

IT SHOULD SHOW UP SOMEWHERE ELSE BEFORE YOU BLOW UP YOUR MOTOR, my lifters started raising hell is the way i know it.

I bought a 80 Chevy van once. It was burning oil and had oil seeping out of the PCV valve. Bought it cheap. Drained 4 gal. of Oil/fuel out of it. Changed fuel pump and re-filled engine with new oil. Drove it for two years as a swap meet getter!!