Vacuum fuel pump leaking oil

[Eli's fb]

Thanks Rob, yes there is oil on the subframe. The car has to pretty warm before it leaks. Idiling for 20 minutes, no leak. Both pumps leaking the same spot and one has been rekitted. Try again this week and let you know, thanks again

[Brett027]

Hi Rob, I'm struggling to understand this pump leak. Why would a leaking oil seal on the vacuum side make more oil come out of the breather hole? Surely that seal is to stop the oil mist already going in there from the crank case being in contact with the underside of the diaphragm? If the seal was leaking why would that increase the amount oil in the pump body? Help

[ardiesse]

Brett,

The vacuum section of the late FE, FC, FB fuel pumps is double-acting (sort-of). It has two inlet valves and two outlet valves. In the lower "chamber" of the vacuum pump, the outlet valve vents to the outlet fitting, and then to the inlet manifold via the pipe. This section of the pump is at manifold vacuum, more or less. In the upper "chamber" of the vacuum pump, the inlet valve draws in from the inlet pipe fitting. But the outlet valve vents to the atmosphere instead of the inlet manifold. When the wipers are on and the inlet manifold vacuum drops below say 8" Hg, the upper part of the vacuum pump begins to operate.

The round hole on the body of the fuel pump isn't a breather, it's the outlet for the upper half of the vacuum pump. It doesn't connect to the inside of the pump body, but to the outlet valve for the top half of the vacuum pump. The pump body breather itself is visible just above the outlet - rectangular slot with a retainer staked in place, and traces of metal gauze sticking out.

You're right when you say the purpose of the seal is to stop oil mist from the crankcase getting into contact with the diaphragm's underside (well, top, because the diaphragm is upside-down). The oil seal's supposed to stop oil leaking down the diaphragm pushrod. If it leaks, oil gets into the top "chamber" of the vacuum pump, and over time, will be pushed past the outlet valve and out the hole.

Rob

[Brett027]

Ah I've got it. Thanks very much Rob.

[Eli's fb]

Hi, took both pumps to a guru of holdens I got told about and one seal was in nos pump was deformed abit. Put the kit seal in the nos pump, got his long nose pliers out on the retaining circular clip for the seal,did a slight modification and after two days of driving no leak, touch wood. The seal in the rekitted pump was still good. Thank you Rob and Brett for your advice

[gpi]

shoulda bought an Ek...

[Eli's fb]

Gpi you seem like a top bloke

[Errol62]

Good outcome eli

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[Brett027]

Good info for all of us. Thanks for the post and following it through.

[FJWALLY]

shoulda bought an Ek...

Yeah EK’s don’t leak oil


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