HD6 AED / Starting Carb Leak From Hell

I didn’t want to put @Gungehead’s post into the weeds, as I have a “first cousin” problem to his on a ‘62 3.4.

I cannot, for the friggen life of me, get the AED to not leak out of the bottom banjo (on the AED side itself, I can get the carb side to seal great.

I’ve gone so far as to swap out bridges, AED housings, used just about every variation and combination of gasket, be it the usual fiber washers, aluminum washers, total seal rubber lined, etc. the thing will stay dry maybe 3-5 minutes, then develop the ol raindrop of fuel. Banjo bolt is in great shape, freshly rebuilt carbs, float level is good, AED fuel level is 1/4 of the way up.

Wits end, and am about to smear the mating surfaces with hylomar or weld the damn things together :stuck_out_tongue_winking_eye:.

Any tips, suggestions or criticisms are greatly welcomed.

Hi Jeff,
I had this problem too. I have finally sorted it, I think.i soaked new fibre/fiber washers in water before assembly and then tightened the banjo bolt up with carbs in situ and repeated after a couple of heat/cool cycles. I am a little reluctant to remove the aed as i dont want to break the seals…
Everythink was spotlessly clean and the mating surfaces lightly rubbed down with emery paper.

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Check that the banjo sits absolutely parallel to the mating surface, some judicious bending of the pipe may be required.

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doesn’t take much for a leak to happen that’s for sure, any chance of a hair line crack somewhere? checking surface flatness we’d use fine W&D sandpaper on a sheet of glass, difficult to assess when we can’t see it

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take closeup photos of the surfaces, especially after polishing clean with fine grit paper

If no fault is revealed, I usually use Permatex non-hardening gasket compound on fuel sealing surfaces, seems to work

The Banjo bolt threads should have anti-seize

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I assume you checked the jet diaphragms are good and flexible. Mine had gotten brittle probably due to ethanol. If they are leaking the gas will run out the bottom.

Definitely possible, but I swapped out bits from my stock and it still leaks. There are differences in the down degree angles of each bridge piece, which is interesting being a cast part.

Yessir all new, the carb side is nice and dry.

Hi Jeff,

As Tony says, make sure the surface of the bridge and the shoulder of the bolt are free from nicks and burrs. Dress them with a fine file. I also grease the threads of the bolt as it really seems to facilitate tightening without having to crank on the torque to get a seal.


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I suffered with that problem. If i recall I used an aluminum washer and it was manageable weep.
Ultimately I removed all that junk and converted to manual choke like an E-type. Wasn’t cheap, but the best thing I ever did to that car.

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That’s the thing, (literally) every car I see on a lift, you look up, and the damn thing is leaking, if not in that moment, the stain left behind shows it wasn’t long ago!

It’s an easy junction and connection.

I think the bridge angles are all off just enough that when you tighten the aluminum washer on the float bowl side, it puts just enough downward pressure on the AED end to start a leak. It may actually be better to cut the AED mounting bracket / leave a 1/2” gap between the halves on second thought, so that the bridge is the only shared piece.

That bracket is the culprit as it’s fighting against the angle of the bridge. :thinking: