The Craftmans Shop > New from Old
JCB 803 Saga
awemawson:
Matthew, as far as I can tell the crack has propagated from the root of the female thread that that fitting I highlighted with a red arrow on a photo up thread.
My current hair brained thought is that IF the crack is within the length of the male threaded fitting I can just assemble it with loctite thread seal.
Currently the hydraulic seal is an o ring in a recess under the hex of the fitting, so the 3000 psi pressure is acting between the male and female threads, if that space is full of thread seal I might affect a cure.
Second hair brained thought if that fails is to make up a clamp that bridges the crack, and bed it down with that magic Titanium Putty I used building up the dipper bush
mattinker:
Andrew, another thought, if it's the female that has split, bore oversize re-tap and loctite in a stainless ( or even mild steel) sleeve, threaded inside and out. The "O" ring would then be between the sleeve and the coupling and the pressure taken by the sleeve. A lot would depend on how much space there is around the coupling!
All the best! Matthew
awemawson:
Yes Matthew all those thoughts have been going through my head over night :bang:
There's actually not much space - the female thread is very close to the top of the block.
However, this morning I have managed to get a picture definitely locating the crack - I started the engine and very gently lifted the boom slightly until oil seeped rather than torrented out, and took this picture.
When the rain stops I'll crawl back under, pull out the fitting and measure how deeply it penetrates. I imagine that the female is somewhat deeper than the male on the fitting, so I can possibly make a longer adapter if the threads don't reach in deeper than the crack.
mattinker:
Andrew, pin pointed!
I'm on tenter hooks! Hows it going?
All the best, Matthew
awemawson:
Well I unscrewed the original fitting, and by measurement there seems to be only 2 threads 'beyond' the crack. So I came up with a cunning plan. Indeed the female looks to be threaded deeper in than the crack, so by making an adapter with a longer male part, just maybe I can seal it all up with Loctite Hydraulic Thread Seal.
The hole in the block is threaded 7/8 UNF - 14 tpi and it is made from 28 mm hex bar. I decided to make a male / female adapter rather than try and copy the part that the hose goes on.
So first job - find some 28 mm hex - well I ended up making some from 32 mm stainless bar
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