Similarly the cylinder heads too were longer than I was lead to expect, but here the problem was the valve stem oil seals. These little devices are intended to stop oil being delivered to the rockers finding its way down the exhaust valves and into the combustion space, resulting in dirty exhaust (especially when first accelerated after idling) and 'slobber'. This was a perennial problem with Rolls engines in locos, where they sit idling for long periods (such as waiting while wagons are loaded). The exhaust manifold was in sections with overlapping joints, intended to seal themselves when hot, but during prolonged idling the exhaust cools, the manifold parts shrink, and oil carried over finds its way out and slobbers down the side of the block.
Trouble is, when the automotive version of the C6 – the 'Eagle' in its various configurations – began to show signs of commercial success, Rolls proceeded to standardise on parts that were fitted to the Eagle, and one such part was the valve stem oils seals. Of course, back at Hills we soon discovered that whilst the Eagle seal suited an engine running at working temperature, on industrial engines – read loco - it did not work as well as the earlier seal. Lest this sounds like an irritation but not really any significant problem, remember that we also produced flameproof locos that had to meet very stringent standards, which included cooling the exhaust gas down below 135 deg C which we did by passing it through a 'conditioner tank' full of water. It was a sacrificial system – the hot gas warmed up the water so the 'diesel loco' produced 'steam' from the stack. And yes I did ask if we could install a pneumatically-operated valve on the stack so as to make it go 'chuff chuff' - but I did have tongue firmly in cheek at the time. (Hey, if there was any chance of promotion, I didn't want to rule myself out).
Anyway, as the water evaporated a float valve – like a loo cistern – replenished it from a reservoir tank, and if the water level got too low another float valve sounded a horn to warn the driver. Incidentally, the water also became acidic from various oxides in the exhaust gas, so everything was made from stainless steel or Inconel, and after Shunters riding on the outsides of the loco complained the shoulders on their donkey jackets were disintegrating, and the paintwork north and south of the exhaust stacks had disappeared, we installed stainless steel mesh like pan-scrubbers in the stacks to catch the droplets of acid and return them to the tank. So picture and engine passing an excessive amount of oil and maybe some unburnt fuel into the exhaust system. Oil floats on water so once in the tank it tends to find its way to the top. It then clogs the float valves and stops them working properly. The water level falls, the amount of oil increases and eventually a critical point is reached and it catches fire. A loco with a semi-controlled conflagration, emitting smoke and maybe flame out of the exhaust stack, does not endear itself overly well to the management of an oil refinery.
Now I am not saying that Charlie is in that league, nor is it flameproof, but when the firm rebuilding the cylinder head needed new valve stem oil seals, the rang me to get an engine number so that the Perkins' agents could identify the right part. I had a feeling this might prove problematic, and when I got back into the workshop I realised why. The engine data plate, which should include the serial number, was blank, but next to it was another plate which identified it as a 2C6SB, which means that at some time it was rebuilt with a 'Short block' (which means crankcase, crankshaft, pistons and liners) but whoever did the exchange failed to record the original build number. So I went back home and hunted out the parts book for a contemporary loco engine and passed them that part number. And apparently it is still a good number, just not readily available.
Thus on Wednesday evening we popped down to the shed and went through our stocks of RR bits and luckily, found a bag with half-a-dozen of the valve stem oil seals, which I duly ran over to them next day. At the same time, although we had most of the joints and rings required, we splashed out on a full top-overhaul kit to make sure there would be no delays. In olden days such a kit came from Shrewsbury shrink-wrapped to a large piece of card and had a full parts list to check it off. When it came on Friday it was a box and you have to take their word for it that it's all there.
Also on Friday the heads arrived back by their van, but it was preceded by the inevitable phone call 'I'm on your road but I can't seem to find a house with your name on it...'
Andrew was out late Friday night so it was just after lunch before we got down to make a start. We unloaded the cylinder heads and other sundry items, and put the space heater on. Leaving him to start cleaning the tops of the engine bores to remove excess carbon and smooth the slight lip that could be felt in the tops of the bores, I retired to Charlie's cab and made a start on the re-wiring work up there. As usual, I had prepared a cable scheme to work to, which includes a 12-way SY cable up to feed the new instruments and LED in the desk, so I started with a suitable length left over from a previous job, to bare enough of the ends to reach the various apertures, and then drilled and filed out a fresh one to accommodate the 3-colour LED. As this is to indicate lack or sufficiency of oil pressure, it is going adjacent to the engine oil pressure gauge. I might have finished this job, had I not remembered that the 0.75mm cable was back home, and although I had oodles of 1.5 (to form jumpers between each gauge) that was a bit wasteful for such low current devices, so I moved lower down and started removing the pipework that had once been the feed from the fuel tank to the torque converter.
I broke off for a while to help Andrew lower the heads onto his prepared blocks, after he had employed the official 'injector seat cutting tool' to prepare the tube into which the injector sits, but as he had neglected to bring torque wrench or RR manual with him, we broke off reasonably early as it was getting cold and the space heater needed a refill.
Quite why we had such a late start today remains a mystery, for although I can honestly declare I woke up with a splitting headache, and the sight of snow covering everything outside did nothing to encourage me to venture outdoors, Andrew was much later up. But eventually we did go out, refilled the space heater and got on with things, Andrew concentrating on torquing down the cylinder heads, refitting injectors and finally changing the fuel pump for the overhauled spare while I resumed cabling up the instruments. I also got around to mounting the new oil reservoir for the converter, which now occupies rather a lot of the former cupboard on the right hand side of the desk. On Cheedale, we'll probably put this in the engine bay, but Charlie simply doesn't have as much space to play with.
With the rest of that feed line from the fuel tank removed and the tap capped off, that was about it. Next week it will hopefully see the power unit back together (and I hope, back in the loco) plus more work to make the cab area presentable. Pop back and see how we get on.