TC: AC mechanical fuel pump oil leak

[Fotog]

I'm leaking oil from the AC fuel pump (the original mechanical pump) vent hole.  It's meaningful.  Probably close to an ounce / 30 ml.  when I turn the car off, and I wonder at what rate it does it when it's running.

I rebuilt the pump a few years ago, but the kit didn't include an oil seal for the actuator.  I've looked quite a bit and I think just about nobody includes one.

I wonder though, can I plug that vent hole?  I don't recall where exactly it is located from when I had the pump apart, but probably between the oil seal and the diaphragm.  That would make sense to me.  If so, its purpose was to relieve pressure between the seal and diaphragm during the pumping and it no longer applies.

Thoughts?  I'd love to plug that hole and see how much leakage I have then.

Thanks, Vince

[TurboFource]

Says here you probably have a torn diaphragm .... https://d29y7fsthxbb26.cloudfront.net/cache/400-400-/catalog/graphics/2/12-02438.jpg

Plugging the hole would probably put the gas into your oil pan.....

[jbcollier]

If oil is coming out the fuel pump vent hole, you have engine wear/breathing issues.  Either you have too much blow-by or the breathing system is restricted or blocked.

[TurboFource]

Thought it said leaking gas.....

[Fotog]

If oil is coming out the fuel pump vent hole, ....

That's even with the oil seal missing?  Just checking...

I can add the additional information that the oil level might be a bit higher than it was previously.  After my original oil change a couple of years ago when I got the car going, I re-filled with the specified quantity of oil, and the dipstick read over-filled, so I reduced the amount.  I've since done an oil change, and then recently, after changing the 'oil breather' (head-to-block rubber drain tube) due  to excessive leakage, I added more oil.  Not exactly willy-nilly, but less concerned about exactly how much.  I aim for the low side of "ok" on the dipstick.

When I first did the oil change, I consulted here about the disparity between specified quantity of oil and dipstick reading, but I felt like there was no certain resolution.  So I'm kind of winging it.  Don't want to put in too little, but wary about oil frothing.  Pressure has been good and I see no sign of froth the way I've been running it.

Any further thoughts?
JB-  If that's what you think, do I do a leakdown test (new for me)?
-Vince

[Pfreen]

My tc dipstick read about 3/8" over the "full" mark when I added the specified (9 us pints) amount of oil to a dry engine after it ran a bit and filled the oil filter and oil cooler and then waited 1/2 an hour for the drain back to occur.

I have rebuilt the engine and determined that this level was not too high.  I do know that the oil pressure was inconsistent with the oil level at the low level on the dipstick.
So, I just scribed a new full line on the dipstick. The variation is ,I believe, caused by how deep the dipstick tube is pressed into the ( I think) front cover. 
I use an electric fuel pump so I can't help with that issue.

[jbcollier]

“That's even with the oil seal missing?  Just checking...”

What oil seal:

http://lotus-europa.com/manuals/tcparts/e/eh.htm#X026E0370W

It’s a rocking lever.  How can you seal it?

[Fotog]

The seal is between the lower half of the body and the actuator rod that moves the diaphragm.  First picture.

Other photos show the location of the vent hole and the approximate location of the missing seal.

It seems that now several sources in England may have it, but identifying the correct part could be difficult.  I'm wondering if the present diaphragm is made of materials that don't require sealing from the oil.

Thanks for the oil level info, Paul.

Vince

[jbcollier]

I stand corrected.  I have a Kent powered Seven and I've switched to an electric fuel pump.  I took apart the original pump and there was indeed a low seal/baffle under the diaphragm and the pump breather hole.

Even if you can find the seal, I would recommend going to an electric pump.  Ethanol fuels are hard on vintage fuel systems.  I'd rather have a failed diaphragm happen at the back, well away from the engine. YMMV

[EuropaTC]

The fuel pump on my Europa isn't the same as that, it's the older glass bowl version and so far (tempt fate) it's been ok with E10.  Even so, I'm with John and have had an electric pump waiting for me to get off my backside and fit it somewhere neat and out of view.

I did the same with the Elan years ago and apart from the fact the materials are selected with modern fuels in mind the other benefit is that if the car has been standing for a while, turning on the ignition primes the carbs without having to churn the engine over on the starter.

If you do want to retain the mechanical pump then personally I'd just buy a new unit. From what I can see the rebuild kits are roughly half the cost (or more) of a new unit and given they're not expensive and easy to get hold of, I'd just fit a new part. For example....

https://www.burtonpower.com/mechanical-fuel-pump-ford-x-flow-ohv-kent-ffp445.html

Brian

[Kendo]

Aren’t you also supposed to install a rollover/impact cutoff switch, so in an accident, you don’t pump gas all over that SUV that didn’t see you?

[Fotog]

Yes, Kendo.

John & Brian- Thanks for the suggestions.  It actually is the glass-bowl fuel pump, from the bottom via a mirror.  There's something I like about it; seems kind of foolproof once I rebuilt it, but I suppose I could get over it.

I actually spent some time looking at Facet pumps about a year ago, but I couldn't conclude what would work.  Actual engineering data is scarce- they don't provide performance curves- and it looked like any that I felt sure had sufficient capacity would likely provide too much pressure at idle.  I'm assuming that I want no more than 4 psi.  Maybe 3.5.  And I'd like to avoid having to get a regulator too.  More complication.

Is there a specific electric pump that you can recommend that should do the job?  Thanks...

-V

[jbcollier]

Yes, this one from British Parts NW:

https://bpnorthwest.com/fuel-pump-electronic-dual-polarity-banjo-mgb-65-to-80.html

Self regulated to 3psi.  You can either mount it with rubber bobbin mounts, or use:

https://bpnorthwest.com/fuel-pump-bracket-mgb-to-1974.html

https://bpnorthwest.com/fuel-pump-mounting-rubber-mgb-1974-sprite-midget-to-1974.html

Pump is very reliable.  We have been installing them for years with not a single issue.

[jbcollier]

Add an inertia switch in series with the power feed:

https://www.amazon.com/Standard-Motor-Products-FV-7-Cut-Off/dp/B000C83MC8/ref=sr_1_8?crid=1LJI3SBXDOLBA&keywords=inertia+switch+fuel+pump&qid=1675795009&sprefix=inertia+switch%2Caps%2C137&sr=8-8

[Fotog]

Thanks for your comprehensive information!

Vince