In mid December 2011 No. 2857 was believed to have suffered a ‘hydraulic incident’, ingesting water behind both pistons but not, curiously, in front. Once 2857 had finished her 2011 ‘Santa’ duties it was decided to strip her down at the front to investigate this area and we made a start on 21st January 2012. Dave Reynolds asked us to remove and visually examine both the left and right piston valves for cracks or obvious deformity. We needed all parties to bear in mind the special stud/integral port bar which we had installed back in 1984 to give added support across the one small crack we found in the Briton Ferry block, at the ‘2 o’clock’ position on the LH front cylinder cover. This stud extends beyond the face of the nut and has two flats which need to be held with a spanner when tightening/untightening this particular nut.

On stripping it down we noticed that the right hand steam chest was full of water. On further investigation we discovered that the pipe connecting the steam chest to its drain cock was completely blocked. The blockage on the left hand side drain was largely due to a lump of weld spatter, about 35mm long x 12mm diameter, too big to get round the bottom bend in the pipe.

The steam chest drain straight steel drain pipes in the Briton Ferry block were exchanged for the ones off the original block and cleaned out in 1984. Both these pipes blocked again subsequent to the 1985 overhaul and had to be cleared out. Again we need all parties to be aware that the threaded connection of the steel pipes into the undersides of the steam chests had to be sealed with Hermetite etc from Day One because we could find no tap to tap out the non-standard Swindon thread, so best not remove the straight vertical pipes at all! If these become blocked our recommendation is to poke a stiff wire or a long series drill up the pipe to clear it in situ. Another reason for not doing anything with these slightly worn threads was that it was impossible to get your hand/head/eye anywhere near where the pipe screws into the steam chest. The problem with these threads floored Pete Simpson and all the other railways that run Western engines, so beware! These Hermetited threaded connections were pressure tested with steam on shed in 1985 and did not leak. It is suggested that perhaps a periodic check should be made from the ground, rather than footplate, that all six drain cocks are functioning – that’s how we realised the middle pipes had blocked in 1986.

Dave Reynolds reported that the back covers had been off and the faces found to be very good and clean, with machine marks still showing in places. The studs were sound with very little sign of pulled threads on the studs or in the iron. The holes were therefore tapped and studs refitted. As there were no signs of cracks or damage in the cylinder or passages, the back covers were refitted and the slidebars set back up. The pistons rods were tried in the lathe for straightness and no faults found. The joint between pistons and their rods were proved and not found wanting. The sliding joints in the valve rings were checked and working and then everything was re-assembled.

By the time he came to write his notes for ‘SVR News’ No. 178, John Robinson had come to the conclusion that, judging by the oily marks around the area towards the frames, the cylinder covers were probably leaking when it came out of traffic last time. Over the years of standing about this must have gummed up so it was not seen on the early light engine trials. However put it in traffic with load, and aided by the occasional wet start, the leak re-appeared.