On 14th Augus the driver reported a knock on the RHS. On steam test the following day it was found that the piston rod taper and cotter was moving in the crosshead so the loco needed a strip down to assess further. Upon strip down the cotter has been found to be bent, there is a broken piston ring and the piston head has been striking the cover. The fitters report that the cover was loose and also when the cover was removed an existing repaired crack has opened up, further investigation saw the cladding removed to see that the crack has also been extended after crack testing was undertaken on site to investigate.
The decission was taken to call in On-Site Casting Repairs who did an extensive cold metal stitching repair, taking some 2 1/2 days. This included addind reinforcement to the original 2005 repair, and extensive crack testingAt the time of writing a new piston ring is being machined, together with new piston ring packings, (reclaimed from old BR Standard packings!) since these were damaged by the hydraulicing. Also it is planned to add an extra oil pot to each crosshead to feed the bottom slide bars, whose lubrication is a bit hit and miss.
The RHS axlebox clearance in the horn guides was also found to be excessive during the steam test, and this will be addressed during winter maintenance. Because of this and the known wear on the piston bores it is probable that the boiler lift planned for this coming winter will be postponed for 12 momths to allow the "bottom end" of the locomotive to be overhauled. It is hoped that the Q6 will be back in traffic later this week.