I'm trying to identify a banjo bolt, Help!

Ian_Edwards

Ian_Edwards

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Whilst priming the Farymann diesel generator, I manage to drop a banjo bolt in the bilge, I've spent longer than is sensible trying to recover it with a magnet on the end of flexible plastic rod, I can't find it. (although I did recover several lost nuts and washer including some SS ones).

Time to buy a new one and some spares, so I ordered from Fisher Panda from the parts list which says they are 8mm banjo bolts, the bolts duly arrived, but they don't fit, they are roughly the correct diameter, but the metric banjo bolts have a finer thread than the original.

The banjo bolts are on the fuel line and connect to the mechanical fuel pump bolted to the engine.

The metric banjo bolts measure a follows.
Shank 7.9mm in diameter, bore 3.8mm, length under side of the head to end of thread 16.35mm.
Thread length 9.3mm and the are 9 threads in that length.

Original banjo bolt.
Shank 7.8mm in diameter, bore 4.00mm, length 16.5mm.
Thread length 9.3mm and the are 7 threads in that length, which is about 20 threads per inch.

These measurements were made with a digital vernier, but may not be super accurate.

The photos, one original bolt and 2 metric bolts, and the mechanical fuel pump on the Farymann 15/18/32 W engine.

I've asked various engineers around the marina and visited several local diesel repair shops to see if I could buy some spares, but could find any, and I can't get a consensus on what the thread is.

The best bet seems to be UNC, and looks about 5/16".

Can anyone identify the banjo bolt?
If I know what I'm looking for, I may be able to find it on the net.
 
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If any help 5/16 unc is 18 tpi 8mm 1.25 pitch is 20 tpi, do you have any 5/16 whit or unc bolts to hand to confirm the thread.
Jim
 
That's an easy easy job for anybody with a lathe and some suitable material !!
Try and identify the thread
Measure thread from crest of thread in imperial see does it divide into 1000 even ? To give t.p.I.
Or check for metric thread measure crest to crest for pitch
Would stainless 316 work for a replacement?
 
I have a Farymann. I sheared the banjo bolt about 15 years ago and struggled to find a replacement. I found out the thread by trying various bolts in it. (afraid I can't remember it now). I bought a part-threaded bolt of the right diameter (longer) I cut the desired length off (now all unthreaded). I drilled a hole up the middle and a couple of holes in the sides. I then threaded it with my own tap and die set and stuffed it in, saying "that'll maybe do until I find a proper replacement". Still haven't found the replacement, but it's doing fine. I don't have any rare taps and dies. I expect it is a fairly normal metric thread being of German manufacture. None of this involved a lathe.
 
Ian, your location is given as Aberdeen, I would take the bolt you have into
Grampian Fasteners Pitmedden Road, Dyce, Aberdeen, AB21 0DP
or
John Smith & Co, PO Box 8, 41 Castle Terrace, Aberdeen AB11 5EAand see if have anything in their stock that fits.

PS Are their any other bolts on the engine that fit the hole, that you could take in to size?
 
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Ian_Edwards said:
The metric banjo bolts measure a follows.
Shank 7.9mm in diameter, bore 3.8mm, length under side of the head to end of thread 16.35mm.
Thread length 9.3mm and the are 9 threads in that length.

Original banjo bolt.
Shank 7.8mm in diameter, bore 4.00mm, length 16.5mm.
Thread length 9.3mm and the are 7 threads in that length, which is about 20 threads per inch.
Click to expand...

Any chance you could have been sent M8 fine (1mm pitch) instead of M8 coarse (1.25mm pitch)? The coarse threaded ones seem to be readily available: see http://www.ebay.co.uk/itm/STAINLESS-STEEL-BANJO-BOLT-M8-x-1-25-/260677992216 for example.
 
Amulet said:
I have a Farymann. I sheared the banjo bolt about 15 years ago and struggled to find a replacement. I found out the thread by trying various bolts in it. (afraid I can't remember it now). I bought a part-threaded bolt of the right diameter (longer) I cut the desired length off (now all unthreaded). I drilled a hole up the middle and a couple of holes in the sides. I then threaded it with my own tap and die set and stuffed it in, saying "that'll maybe do until I find a proper replacement". Still haven't found the replacement, but it's doing fine. I don't have any rare taps and dies. I expect it is a fairly normal metric thread being of German manufacture. None of this involved a lathe.
Click to expand...
Necessity is the mother of all invention ☺
 
I took the banjo bolt down to my local garage and talked to Phil, who is an old hand and an excellent mechanic. He identified it as a M8 x1.25mm banjo bolt, didn't need to do anything but look at it.

JumbleDuck, was spot on, I'd been sent M8 x 1mm banjo bolts by mistake, that's in spite of ordering them by part number from the official Farymann parts list.

Thanks for all the replies, and I'm pleased it has turned out to be simple mistake, and surprised that the diesel mechanics I talked to didn't twig that it was simply the difference between a course and a fine thread.
 
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