The 'E' Type Forum

Despite having the correct washers [brand new] fitted as they should be i.e aluminium washer under the banjo bolt head, and a fibre washer on the other side, I am having trouble getting these to seal properly. I am very wary of over tightening the bolts as the aluminium float chamber lid is not overly substantial. The fuel pump is a standard SU unit. The bolts and inlet pipe have both been plated and I'm wondering if this is the problem in that the mating surfaces are now not as smooth as they should be? I would like to try o rings as an alternative sealing medium - my new SU pump was supplied with o rings rather than fibre washers. I have a selection of o rings that I thought were of good quality, but when I leave them in petrol overnight, the do swell up somewhat which I don't think is ideal. I have considered a thin smear of Blue Hermatite but I really don't want a particle of this to end up being ingested by the carb. I have soaked the fibre washers in engine oil for several days, but this didn't help. Anyway, I'm sure there is a straightforward way to cure this issue?

Andy : these joints need a surprising amount of torque because they are in effect a compression joint as in plumbing . I use a long ring spanner and apply a fair amount of heft at the full length, tightening them initially to apparently full tightness without exerting much effort, and then applying greater effort to turn them perhaps a further one-third to one-half of a flat . It is this last effort which compresses the washers and effects the seal

Andy, the plating might well be the problem as I ended up getting all mating surfaces as smooth and flat as possible to help eliminate leaks. Also it was surprising just how tight you can do up those banjo bolts, much tighter than I felt comfortable with but it solved the leak problem.
I hope this can help

Geoff

If the seals / washers are new and in good condition then they should seal at the connection points mentioned although you did say you had sonme concerns about the surface smoothness [ and ability to be sealed ], due to recent electro plating.

You may be right and these are causing a small leak ? I think that the original aluminium seal will provide a leak free joint but as pointed out, needs major tightening torque. A worry when applied to potetially fragile cast aluminiun perhaps

I wonder if a dowty seal could be a better solution in the 21st century ?

https://en.wikipedia.org/wiki/Bonded_seal

I havent tried this method but have considered it after last time of reconnecting fuel filter and fuel pump

Thanks everyone.
So, I took my shiny plated banjo bolts out, and replaced them with some original unplated ones & gradually tightened them with fuel pressure applied and et voila they are now leak free. I like the idea of the dowty seals though, and I'm pretty certain I have a load of them somewhere so I might look them out and see if I have any of the correct size.

Hi Andy.....re check your banjo,s after a few trips....its not unusual after a rebuild for them to start leaking again..so will need tightening....Steve

I've had the same issue. It seemed to me that the problem is that the diameter of the fibre washer is larger then the diameter of the hole in the banjo, hence the need to keep tightening it until the washer is squashed in the rebate around the hole. If the washer sat against the rebate I don't think there would be this problem.

all the best
Tim

Hi Tim....washers i use are direct from Burlan.....perfect fit.....still needs re tightening.....Steve

Steve, I bought some washers over the counter at Burlen and they admitted they were not all the same size
Andy, watch out for the fuel compatibility of the Dowty washers. If you find some of the correct size please let us all know.

Geoff

Hi Geoff...will keep a look out....iv never had one that didnt fit correctly.....Steve

Most people I know, including me, keep an appropriate ring spanner to hand for the regular re-tightening that seems necessary on these things.

This topic sprang a leak and has reappeared here

http://forum.etypeuk.com/viewtopic.php?p=140814#p140814

so let's re-centre it.

I'm curious about references to aluminium washers being used under the banjo-bolt heads ?

We are of course referring to the petrol feed banjos, and I had always assumed they were clamped by fibre seals C11489 AUC2141 on either side ? As confirmed page 33 of J30.

The alloy washers on my car 7120 AUC1557 are under the breather banjo bolt heads, with the fancy scalloped breather fibre washers AUC1298 - being between the banjo and the lid, again as per J30.

I have a weep on just the rear carb, at the feed banjo, and no amount of tightening will cure it so will have to dig deeper.

Rory : you will not welcome this, but if you cannot eliminate the leak with new fibres, may I suggest you inspect the carb lid carefully, preferably under magnification, for a crack around the thread area