Banjo Bolt Blues (How to fix a leaky WUR?)

[area man]

I just got the engine back in after a bunch of work over the winter and the car was running fantastic, but there was a little leak in the fuel line banjo fitting on top of the WUR. I never changed the sealing rings, so I figured that should fix it. I ordered new ones from Pelican and put them on, and lo and behold the leak got much worse (see pic below). The older sealing rings were actually in better shape, so I put them back on and went back to the original, small leak. I figured the bolt just wasn't tight enough, so I cranked it down a little and... off came the top of the banjo bolt! ugh.

Any clues to why this is happening? If I leave it loose, I get a leak. If i tighten it down, the bolt breaks. what gives?

And does anyone know how to get one of these quickly? Our host is out of stock on them and won't get a new one for about ten days. Part number is 911 110 899 00

[Nine9six]

Its not rocket science...Measure the existing banjo bolt (metric) and source a new one. If you dont know how to measure or gage thread pitch and size, take it to an autoparts house and have them match it up for you.
P.S. There should be crush gaskets on both sides of the banjo bolt. Dont hamfist it, the crush gaskets will seal the leak (use new crush gaskets)

[area man]

That's what I just did! Two new sealing rings, correct size as per PET file, and still had the leak. That's why i went the extra step in tightening them. Thanks for the input though.

[1QuickS]

The sealing surfaces of the banjo bolt, the banjo fitting and of the interfacing surface below the gasket must be flat and free from burrs. Also, if the sealing gaskets are not aluminum (a hard fiber material) then they may have a textured surface that WILL leak. I sand the gasket faces smooth and resurface banjo fittings, banjo bolts and the mating surfaces on the Weber carbs I service; if I don't also smooth the hard fiber gaskets then they routinely leak and there is only 3.5 psi pressure. I found that the gaskets needed smoothing to correct the issue.

[area man]

That's really helpful Paul, thanks. I should have thought of that. These are aluminum sealing rings so they're pretty smooth, but the mating surface on the bolt probably had some burrs. I'll take some fine grade sandpaper to the new hardware and the banjo fitting before I install it.

[boyt911sc]

areaman,

Go visit your local auto dealership service centers (foreign cars) and talk to some mechanics about this 8 mm crash washers. I got all these crash washers from mechanics (Audi & VW) for nothing. Most mechanics have bucket/s of assorted nuts and bolts, and they throw these extra small items after a repair.



Tony

[area man]

Good idea Tony - I'll try that.

Btw, you were right about the airbox on my SC - it was blown at the seam, on all sides. I took it apart and reglued it over the winter. Engine is running really well now, though I haven't gotten the A/F mixture properly adjusted yet.

[Ronnie's.930]

Another thing that works really well in situations like this is to paint both sides of the seal rings/washers with VersaChem Prime Seal gasket sealant (type 3 aviation) . . . this can be found at most autoparts stores. It is of very thin consistency, non hardening, intended for metal-to-metal sealing, and resists gasoline. There will be people that come on here and say "don't do it / band aid fix" and the like, but I have done this for over 20 years in similar situations (including on the WUR and fuel head of my current 930) and it works!

[timmy2]

If you don't find a banjo bolt locally, I'll send you a good one for the cost of Priority mail with 2 new copper sealing washers. ($6 by Paypal)
I read your PM, let me know tomorrow some time before the post office closes.

[area man]

Thanks Dennis - Paypal sent.

[timmy2]

Banjo and washers are in the mail. Let us know how it works out.

[DanielDudley]

My guess is that the bolt was already defective, and would not pull down correctly because it was already cracked.

[boyt911sc]

Originally Posted by DanielDudley

My guess is that the bolt was already defective, and would not pull down correctly because it was already cracked.

DD,

Even a hand tightened banjo bolt would not leak (gusher) this much. It would leak or drip out but not the kind of flow shown in the picture. The top section of the banjo bolt has fractured when it was over torqued during the sealing process. Keep us posted.

Tony

[area man]

I got this sorted out over the weekend. The problem was the underside of the bolt - it was heavily scored and basically fit to the old sealing ring, which is why the leak got worse instead of better when I put the new rings on. So as Paul said the problem was the mating surfaces - either sand down the old ones or get a fresh bolt and washer. In this case the problem was caused by matching an old bolt with a new sealing ring.

I doubt the bolt was fractured. The picture I posted was a little misleading - the spray only happened at the moment I turned on the fuel pump, and after that it quieted down to a dribble (I used that photo for dramatic effect ). Once I had a new bolt and new rings on it took very little force to tighten it properly and have it leak-free.

Thanks to Dennis for the speedy delivery of a banjo bolt and rings.