Carburettor banjo fibre washer leaks

[PhilBell]

Couldn't find this topic by search but I'm sure it's come up before.

To avoid the fibre banjo washers on the fuel feed to the float chambers leaking I have to retighten the banjos before starting. Every time. Eventually, after weeks of this, the new washers seem to be compressed enough for no more tightening being possible, and the leaks finally stop. Any work needed on the carbs means back to the start of the loop. Pre-soaking the new washers in fuel for a day or two makes no difference.

Whether I buy from SNGB or Burlen makes no difference. Anyone found a better source or washers of the same size but made from a better material?

There must surely be an engineering solution to this extremely tedious and dangerous problem.

[christopher storey]

How tight are you torqueing them initially ? They require, I find, a very significant degree of tightness which is surprising considering that they are screwing into die-cast alloy . I use a good deal of heft on a longish ( 10" ??) spanner and I would estimate the torque at perhaps 30 to 40 lbs-ft

[Gfhug]

Phil, those fibre washers are poor IMHO, although they do an aluminium washer alternative but I've found that can be just as prone to leaks. The faces of the fuel bowls and pipe joints can often do with a good skim to get them flat, I've found, but that's a complete dismantle job.
Oh for a decent rubber/nitrile/butyl or appropriate washer to cope with old, imperfect jointing faces.

Geoff

[timhum]

Coincidentally I was about to post on this same subject. My impression is that the washers available are of a slightly to large a diameter. It looks as though the washer should fit into the groove in the circumference of the banjo fitting. The bolt has a shoulder which should compress the washer. By being slightly too large they don't fit comfortably into the housing and hence getting a good seal is difficult. I have also had to tighten them several times and am still not comfortable that they are completely leak free.
Does that seem a reasonable conclusion and if so is there a source of smaller diameter washers?
thanks
Tim

[abowie]

FWIW, as far as I can remember I've not had any problems with leaks here on the last 3 or 4 cars I've done.

We use the genuine SU kits from Burlen with fibre washers, so these are what you are probably using.

I do them up pretty tight; I have a double ended ring spanner about a foot long that I usually use, and I tighten them as far as I dare with this, so certainly over 20 lbft. I haven't stripped or cracked a lid yet. The washers are pretty tough and don't seem to deform.

I have also used the ally washers and these seem good too. Maybe source some of them and try them instead?

[Gfhug]

Visiting Burlen to buy washers, they showed me a selection which were of different diameters and certainly wouldn't fit nicely into the shoulder area of the banjo and I don't think the ally washers will at all.
They didn't seem at all concerned about the poor fit

[Geoff Allam]

FWIW many years ago shortly after acquiring my coupe I rebuilt the carbs. On installation I had one banjo that leaked. I progressively tightened it a couple of times and it did strip out the threads on the float chamber. Lids were cheap then so no big deal. Now not so much. Since then I have used a light smear of permatex #2 on each side of the fibre washer whenever replacing them and they seal with much less brutality. Permatex #2 is actually my sealer of choice for almost any gasket job. I find it seals much better than the silicone type product and not as much concern about ”sealer worms”.

[timhum]

Thanks for the advice everyone. I didn't realise how much the bolts should be tightened so gave it a try and the problem seems to be solved. It would be good to be able to get some correct size fibre washers.

Tim

[PhilBell]

Has anyone tried re-using their carb banjo fibre washers rather than fit new ones? Whenever I fit new ones there follows a two-month routine of having to retighten them before each occasion when I start the car until eventually they don't leak. My theory is that after multiple rounds of wetting with fuel and being further compressed with each tightening, they can compress no more.

[paulsco]

I use Wellseal on my fibre washers. It is highly resistant to most fuels.
It works for me.

Paul

[PhilBell]

Thanks Paul, and I have some left from fitting the new head gasket a few years ago.

[tbone]

I had the same problem with my 1963 3.8 after a complete rebuild with new washers and clean seats. No matter how tight that I dared to torque them, they weeped. THEN . . . I measured the fuel pressure at the output of the filter. It was four times the book value! Took out the fuel pump and adjusted the set screw that controls pressure. End of problem!

[PhilBell]

I recall someone suggesting that my problem with leaking fuel unions might be caused by excess pressure. My fuel pump is I believe based on an XJ S3 pump designed for fuel injection so likely to run higher pressure than the original S1 SU pump. The suggestion was to fit an inline pressure regulator but I can't find the post. Has anyone done this and if so, which regulator and where best to fit it?

[mgcjag]

Hi Phil....just search through your previous posts. ...or search fuel pressure regulator....Steve