Packard Forum Index » Post-War (1946-54)

I put on a rebuilt fuel pump and its been working great until now. Its leaking out of the hole in the middle of the pump.

That hole is probably an air breather or relief hole above the diaphragm and a leak there would tend to indicate an issue with the diaphragm. Possibly it was too tight and has developed a split or crack. This can happen if the two halves were screwed together and diaphragm was clamped down without the arm being held against the spring so diaphragm was at its maximum or full stroke when tightened. Another possibility is if it was an old NOS pump or one rebuilt with an NOS original rubber rebuild kit Ethanol or some other additive in modern fuel has destroyed the diaphragm.

If it is leaking oil out that hole, you might as well just grin and bear it. If it is fuel, you need another pump.

Mine does this as well, thankfully just oil. I THINK that breather is supposed to have some sort of filter media. I know mine doesn't have anything in there, so I can usually see a little spritz of oil occasionally when I'm working on that side of the engine. Doesn't seem to bother anything. Just occasionally wiping down the heat shield and pump.

Some of the pumps used what looked like a small gob of horsehair in the vent aperture. I'm not sure what retained it and kept it in place.... and out of the crank case.

Its leaking fuel out of it. Its been good for 5 years. Until now.

If it's leaking fuel at the vent holes, the diaphragm is ruptured. The pump will need a rebuild or replacement.
It is probably leaking fuel into the engine crankcase, too, so don't delay fixing the problem. I would check the oil for excess thinning or a strong gas odor.