The Stovebolt Site Forums The Shop Area The HiPo Shop Mechanical Fuel Pump leaking oil

I have a Mechanical fuel pump on a 350 Chevy. It is a Mr. Gasket performance pump. It is leaking oil. This is the second pump that I have installed. The first one leaked oil and the performance shop replaced it. The second one started leaking oil so I disassembled it and sealed the gaskets with some RTV. It did not leak for awhile, but now it is leaking again. I think these pumps are junk! What could be causing this problem. Is it a poorly made pump or could there be something else with the engine causing the problem? Also I am thinking about replacing the mechanical pump with a electric pump. How should this be wired into a 1966 Chevrolet C-10?

Do you have any type of crankcase ventilation sytem? you need at least some breathers on the valve covers, and a PCV system isnt hard to retrofit onto that engine. It sounds like you have too much pressure and its blowing out the seal(gasket).

I have a breather cap on the drivers side valve cover and a pcv on the passengers side. The engine has a supercharger on it. Is it possible that the intake pressure is making its way to the crankcase? I do not get any leakage from other lower block seals that you would think would leak if there was an excessive pressure buildup in the crankcase.

Is there an oil line on your particular super-charger? If so, the seal there could be blown and causing pressure to get to the crank-case.
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If you have been running it hard, the rings may be worn and causing pressure to enter the crank-case.Have you done a compression check?

The supercharger that I am using does not have an oil line connected to the crankcase. It has a self contained oil bath in back and front of the supercharger case. The engine is a brand new GM crate motor with about 4000 miles on it. If I was getting pressure blowing by the rings then wouldn't I find oil leaking from timing chain cover, oil pan and other areas. I am only running 6 psi of boost at the most. I will do the compression test to eliminate that possibility.

Is your SC draw through or blow through? Is there a check valve in the PCV line?

hello 2prfxn. inside of the cavity where the fuel pump arm meets the pump push rod is a drain hole that lets the oil back into the oil pan. check to see if that hole is clogged, or that the oil pan gasket is blocking the bottom side of the hole. if either of these two things have happened, the oil lubing the pump push rod will fill the cavity and come out of the weep hole.