I have finally found my fuel leak. Its the pipe from the filter bowl to the carbs. Part number C14492.

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I have found two parts, a braided one (same as currently fitted) and a nylon one. Any advantage to the nylon one?
Should I replace the banjo bolt?
I assume I should replace all the washers/seals?

Cheers

Rishi

 

Either will work OK.
The banjo bolt should be OK as well. No need to replace it unless the head has been butchered/damaged or the screw cross threaded.
It is worthwhile to replace all washers and seals as you are not sure of previous maintenance.
Any fibre washers should be immersed overnight in kerosene/paraffin/diesel or similar prior to initial fitting. (Softens them up slightly)
Cheers

 

I find putting a thin film of grease on all mating surfaces, including the threads is a must.
This helps the fibre washers to "seat" properly and prevents galling of the threads on the soft aluminum.

 

Not sure where your leak is but just to mention that its critical that the gaskets on the float chamber tops are present and in good condition, otherwise it can appear as if there is a leak from the banjo union on the fuel pipe.

I spent a load of time (and money) chasing this issue on an S-Type 3.8 i owned until I found this and then the problem was fixed.

 

This time it was easy. I had smelt a strong petrol odour for a while but could not see/feel anything. Yesterday I turned on the ignition and as usual waited for the fuel pump to stop but it didn't. A quick inspection showed two thin jets of petrol coming out of the middel of the braided pipe. I assume the rubber pipe under the braiding is shot, I guess that is the problem with braided pipe, on the outside they always look good.

 

Not sure what fuel you have in the Netherlands but in the UK we have both E5 and E10 unleaded. The E10 with the higher Ethanol content rots rubber for breakfast so if this hose is older than 10 years it might have been effected by the E10 fuel causing the leak. All modern fuel lines less than around ten years old are suitable to run E10 as is the Nylon hose that you have shown above.
I changed all my fuel lines when I did my rebuild 12 years ago and had two stainless steel braided rubber hoses from the fuel tanks to the fuel pumps that started to rot out and leak. The rest I have replaced as a precaution but I run on E5 fuel all the time now. Slightly more expensive but for the amount of miles I do it is insignificant. I have also had my carbs rebuilt with all new E10 compatible seals.
Last thing you want under the bonnet of a classic Jag is a fuel leak and fire.

 

I only use E5, even on my XK8 I use E5 whenever I can. When I started smelling petrol the first thing I did was get a fire extinguisher for the car and the garage. Its my greatest fear. I have also put an isolation switch on the battery to ensure that I always disconnect the battery whenever I am working on the car or not using it for a period.

 

There are SAE standards for rubber hose for use with fuel: SAE R7, R9, and R12, where the number increases with the severity of the application. R7 is for moderate pressures as in carburettor systems; R9 for fuel injection pressures; R12 resists high temperature and pressure. All have adequate chemical resistance and any for automotive application should have the grade marked on it.

The main point in favour of rubber is that it's flexible and relatively easy to fit. Some types, such as neoprene, will fail rapidly when exposed to gasoline especially if there's ethanol in it so it's not safe to use any old piece of hose. Almost all rubber has some permeability to fuel. That's not a problem under the bonnet or under the car, but makes rubber generally unsuitable for enclosed spaces like the passenger cabin and probably the luggage boot if your wife's nose is as sensitive as my wife's. If you can find it and organise end fittings, the very best material for fuel pipe is what Jaguar used originally for most of the fuel lines on the Mk2 and that's nylon. I'll emphasise nylon, not PVC that may look like nylon, but is useless with gasoline.

 

We are fortunate in Australia that we can get 91,95, and 98 octane petrol without any Ethanol blending.
E10 fuel is also sold but with only a typical saving of 4 cents per litre against 91 octane and most people ignore it.
Hence my lack of awareness about the problems with rubber encountered in countries where ethanol blending is mandatory.

 

I went with the braided version. There was just enough room to get the spanners in. No more leak and that strong smell of petrol I have had for a long time is gone. I think the rubber was first just a little porous before it actually sprong a leak.