My 1948 B32 (same engine as B31) has a persistent small leak from the inlet rocker oil feed banjo. I've tightened it as far as I dare for fear of shearing the banjo. Any ideas on how I can stop the leak welcome. Ideally I guess I should remove the rocker spindle and lap it to the inboard face of the banjo and do the same with the banjo bolt to the banjo but I really don't want to remove and strip the head at this point in time.
It also occurs to me that I should check the soldering at the banjo although the leak seems to be from the inboard banjo face rather than the soldered joints.
Not exactly the same problem, but I had an irritating leak from the rocker bolt on the outside of rocker box on my Starfire.
Solution was remove it for a proper clean and carefully apply a decent silicone sealant (a black loctite one, can't remember the exact number on the tube) around the thread and washer. It's been fine since.
I'd imagine a similar thing would seal the banjo too.
I tried wellseal first as its my jointing compound of choice, but the heat made it runny, so no good.
Can you fit a dowty washer?
Quote from: cdsdorset on 08 Jul, 2022, 21:55
Can you fit a dowty washer?
No, if only it were that easy. The banjo buts against a taper on the end of the rocker shaft and is held by the banjo bolt which has a similar matching taper.
There is a fibre washer listed on the original drawings.
Quote from: cdsdorset on 09 Jul, 2022, 11:10
There is a fibre washer listed on the original drawings.
Interesting. It is not shown for the 1946 or 1949 bikes, mine is a 1948 and has no washer, but a fibre washer is definitely shown in the 1953 parts list. I'll look out a couple of suitable sized fibre washer and see how that works out.
I made sure the mating surfaces on the rocker spindle and the feed bolt were cleaned up with fine emery cloth and then just used a thin film of Wellseal.
I found the fibre washers tended to crack before a reasonable tightness could be achieved.
Done a few hundred miles now and still all dry.
Pete
That is why I suggested a dowty washer.
Well, I found some small fibre waters that will fit between the end of the rockers spindles and the banjo. Next time I take the bike or a run will tell if they are successful.
I'm dubious of the whole prospect as the end of the rocker spindle has a taper that fits into a matching(?) taper in the banjo. The banjo bolts have similar taper to fit with the outside of the banjos. Although the small fibre washers I used will deform to the taper and will hopefully help.
I can only imagine that a Dowty or larger fibre washer will need to go over the outside of the end of the projecting rocker shaft and bear against cylinder head and the flat outer edge of the banjos. A fibre washer would need to be quite thick as the gap is around 2mm or so.
You do not fit a washer on the taper. The washer should be fitted over the end of the shift so that the banjo tightens against it.
Quote from: idie on 11 Jul, 2022, 13:42
You do not fit a washer on the taper. The washer should be fitted over the end of the shift so that the banjo tightens against it.
That's what I was thinking might be the case. It seems that originally BSA intended the taper to make seal but at a later date added the fibre washers to seal between the banjo and the cylinder head, making the inner taper redundant.
A bit more investigation and I think I know why all the replies suggesting a Dowty or fibre washer between the banjo and the head won't work on my bike.
BSA changed the rocker oil feed pipes for 1951 onwards. Pre 1951 bikes used part no. 65-1119 for models with a one piece pipe and 65-1364 for those with a flexible joint. 1951 onwards uses 65-1544 for the one-piece pipe and 65-1547 for that with the flex joint.
So it seems that up to 1950 they relied on the taper to make the seal but from 1951 on used a different feed pipe that enabled a fibre washer to be fitted between the banjo and the head.
The attached photo of mine shows that the banjo is too small to accept any type of washer between it and the head.
the washers need to be a very snug fit, inner diameter 5/8 inch (15.9 but realistically 16mm)