Overhaul of the cylinder heads for Sherwood got off to a bad start. Having gone to all the effort of cleaning them and lapping in the valve seats, hairline cracks were revealed in the exhaust valve seat of the first head. The picture shows three radial crack across the valve seat, which is a hardened ring pressed into the head. The middle crack extends further into the head, which is made of cast iron. This was an all too common problem with Sulzer cylinder heads and often occurred in this position next to the injector hole (at the top), which must be a weak spot in the casting. The picture also shows where this area has been ground away from a previous repair where another crack was probably metal stitched.
It must have been our unlucky day, as three out of the first six heads have similar cracks. If we put them back on Sherwood, they would probably run satisfactorily for many years, but there would be a small chance that a piece of a valve seat could break away and do damage to the valve or even the turbocharger blades. We don’t want that inconvenience, and so the heads will be scrapped and replaced.
Jacob, Nathan, Matt and Malcolm had a good day on the spanners, disconnecting the fittings on B-bank cylinder heads, extracting the injectors and craning out the inlet manifold. Next job will be undoing the cylinder head nuts.
Carl completed the welding of the nose end floor area with a new strip along the back edge, and coated the lot in priner.
A flying visit to Wirksworth on Saturday followed delivery in the week of a barrel of antifreeze from Morris Lubricants. After rolling the drum off the station platform and 200m down the ballast, it was positioned alongside the loco and the wicked blue stuff pumped into the engine. A garden hose was used to top up the rest with water, a somewhat tedious process! Hopefully next weekend we can fire up the engine and recharge the batteries.