Lotus Elan

Leak from Banjo's on Dellorto's

PostPost by: Roland » Thu Feb 08, 2024 3:23 pm

I seem to have had problems with fuel leaks today. The car was run a few weeks ago and when I returned from a short run I replaced the fibre washers on both Banjo's at the carburettors (Dellorto's). I tightened them both up but didn't run the car again.

I started the car today and had fuel leaks from both Banjo's. The Banjo's weren't loose but they were not as tight as I left them, so I nipped them up. The Banjo's were still weeping even after I had gone as tight as I could safely.

It looks like the leaks are coming from the fibre washer on the inner side of the Banjo's near the carburettor. This washer is much thicker than the washer it replaced and it looks to me that fuel is travelling through this washer, in other words its porous. It came from Eurocarb so it should be good quality?

I am running a mechanical fuel pump which was recently rebuilt and which I measured at 2.4 psi, the Banjo's shouldn't leak at these pressures. I also pulled the float bowl covers off just to check if the bowls were being overfilled but the levels were fine.

Has anyone had problems with these fibre washers, they do look thick. I kept the old washers so will put those back in and see if everything is OK.

Regards

Roland
Roland
Second Gear
Second Gear
 
Posts: 140
Joined: 09 Aug 2019
Location: Aberdeen

PostPost by: 512BB » Thu Feb 08, 2024 4:27 pm

After I have been messing around with Dellorto carbs, that involved replacing the fibre washers, they have always taken a few rounds of tightening the banjo bolts before they finally seal without weeping, and they have really taken some torque to stop the weep. So much so, that I thought they would break, but they never have to date.

So just run the car up to temperature a few times and check them. Let cool. If there are then any signs of petrol, give the banjos a bit more, until completely dry.

Leslie
512BB
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 1100
Joined: 24 Jan 2008
Location: Cambridgeshire, UK

PostPost by: Craven » Thu Feb 08, 2024 4:44 pm

Yes, like many things these days just not the same. So called replacements I have tried are just rubbish delaminate and cannot be reused almost paper based. Density of the fibre is just not there, seems to be all sizes of red fibre washers not just on carbs even the cam cover fixings are the same. Fortunately back in the seventies I bought box of 100 cam cover size, imperial, and can assure you its chalk and cheese comparison
Craven
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 1607
Joined: 14 Sep 2013
Location: south coast uk

PostPost by: Roland » Thu Feb 08, 2024 6:22 pm

So there are a few things wrong/different with these new fibre washers compared to my old ones:

1. The inside washer near the carburettor is 65 thou thick rather than 40 thou. It is made from a very hard fibre and I think does not deform easily. The Banjo bolt is an Aluminium alloy and it really can't provide the clamping force to seal this washer. I doubt the washer is porous though.

2. The outer washer does not sit tight on the machined section of the Banjo bolt, so it doesn't self centre properly. I did get this washer to seal though.

3. The inner washer near the carburettor does not sit tight on the threaded section of the banjo bolt. So again it doesn't self centre properly.

I put my old washers back in and a simple nip up of the banjo bolts and I have a good seal that I have confidence in.

I would say those new fibre washers from Eurocarb are risky in a car which you really don't want fuel leaks. I had the banjo bolts pretty tight and I was still weeping fuel. I guess someone actually sells the correct fibre washers?
Roland
Second Gear
Second Gear
 
Posts: 140
Joined: 09 Aug 2019
Location: Aberdeen

Total Online:

Users browsing this forum: No registered users and 5 guests