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MG MGA - Carburetor Elbow Leak

Just got my SU carbs back from being rebuilt. I put them on the engine and turned the fuel pump on for the first time. I see a leak coming from the joint of the 'Y' elbow (yellow arrow) where the fuel comes in from the tank and Y's off to each carburetor. The bolt is tight and I'm afraid if I tighten it further, I take a change on breaking the cover.

Which way does the elbow attach

Michael O'Brien

Michael, there should be two fibre washers. One fits inside the recess which should be towards the banjo bolt head. The other one between the banjo and the cover as shown in your picture.
Lindsay Sampford

Yes, there are two fiber washers. One is inside the recess and the other is towards the banjo bolt. But they are leaking. How do I stop the leaking?
Michael O'Brien

I can't help with orientation, but you shouldn't need to use any sealant there.
Dave O'Neill 2

They can be a real pain to get a seal! I have found that if they are disturbed after they have been in service for a while they don't re-seal. It maybe that the fuel hardens the fibre washers. Are your washers new? Are they the correct type? The banjo bolts do have to fairly tight. Hold the float chambers whilst tightening the bolt.
Lindsay Sampford

I had the same problem - look in the archives under "petrol leak". As Lindsay says (and advised me) make sure the fibre washers are new. There is also a suggestion to double up the washers.

I was advised to put a lot of pressure on the spanner when tightening, which did work for me, but I understand your concern of doing some real damage, so you need to decide on how tight yourself, I guess.

If it were me I think I would probably use an extremely light spread of Hylomar Universal Blue.

Graham V

Torque it down until the threads give way, then back it off 1/8 of a turn :-). Seriously, torque the banjo bolt very hard, Those are the same on the later SU fuel pumps used on the MGBs and those threads will take a tremendous amount of torque and not strip. Cheers - Dave
DW DuBois

Try using aluminium or copper washers. Anneal if not new, wipe aluminium with soap and heat until goes black, air cool. Copper heat cherry red and air cool. This will soften washer and they will seal easy. Anneal each time you open the connection as they work harden. More forgiving than fiber washers.
Mike Ellsmore

I thought that copper was annealed by heating then quenching? That's what we always did for solid copper motorcycle head gaskets.
Lindsay Sampford

Your right Lindsay water quench. I was getting carried away.
Mike Ellsmore

Dreaded Carb. leaks.
My car had an infrequent fuel leak from under the rear carb.
Tried several sets of float bowl seals made from different materials. The leak persisted.
Apart from preventing a likely fuel fire, the smell of petrol inside the closed garage, following a run---just annoyed and annoyed.
It is hard to look-see, under there to examine the cause.
Finally--the plug in the end of the float bowl link passage adjacent to the mount bolt was seen to be the problem.
Placed some synthetic 2 pack gunk over it--fixed.
However, building Electric Fuel Injection onto the Coupe'---this innovation has fixed all of this old annoying stuff--Brilliant.
Anyone needing a nice choke cable and carbs. going cheap??
I.W. Cowen.

Check for corrosion on the carb side. May need to use a file to get a true flat.
I disagree with the need for going "very tight". This is only 3 psi.
Art Pearse

I cut those out of gasket material. Both of my cars now experience no leaks.

The problem is the red fiber washers don't conform to a less than perfect surfaces.

I have had mine off many times over many years and no leaks. Perhaps I am just lucky. What does the guy who rebuilt the carbs say about it?

Paul Dean

Sorry for the late answer but I am moving at the same time. I have to pack and move MGA parts, two dismantled TD's. So I am having lots of fun.

I went out and re-tightened the bolts on the carburetors and that appeared to stop the leak. They were in fact a little lose - I thought I tighten them. I checked around and drove the car and re-checked that there were no leaks.

Thank you all for the responses!!

-Michael O'Brien
Michael O'Brien

This thread was discussed between 25/02/2017 and 04/03/2017

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