A bit of a boring one really, as it concentrates more on a single part of the engine but ill try and bed it out a bit more with some more slightly interesting bits.....
A view of 26043s 6LDA with both side covers removed (reason why will be explained in a bit)
In this view you can see where the block is bolted to the crankcase, and you have a good view of the camshaft, there are 3 cam lobes per cylinder, the outer 2 of the lobes operate the pushrods and the centre lobe operates the fuel pump, also note that the camshaft is gear driven (a common sulzer trait), as opposed to the chain driven English electric engines. This eliminates chain stretch and failure as an issue for timing (which is a common issue on English electric engines) the cam Is driven by a pair of reduction gears from the main camshaft, each individual component is bolted to a central shaft. Above the lobes you can see the cam followers which are effectively 3 individual "pistons" which rise and fall on the lobe to operate the equipment they connect to, a push rod or a fuel pump.
Another view, the shelf above is the fuel gallery, which contains the fuel pumps and push rod tubes (all removed for overhaul) just below that you can see the fuel rack, which is a mechanical linkage which connects the engine governor to the fuel pumps so the governor can control (according to the drivers demand) the speed of the engine. over to the left (out of view) is the overspeed trip which is a mechanical device which is connected to the cam shaft, in the event of on overspeed the cam shaft will lift a spring which will snap the fuel rack closed and shut the engine down. The black pipe running along the cam shaft is the oil supply rail to the cam shaft bearings and lobes. At the bottom you can see the engines main oil filter.
One of the engine side covers being steam cleaned, 3 layers of paint were steamed off this ready for repainting, you can see the 6 Kyocera valves, which have had there covers removed, The job of the valve is to vent dangerous amounts of crankcase pressure which is not being vented through the crankcase breather (which has a labyrinth) and also to limit damage as the result of a crankcase explosion. these valves are unique to sulzers, and were retrofitted to all sulzer engines at some point in the 1960s, prior to this they had just a solid door. This came about after a peaks crankcase exploded do to a build up of iron filings at one end of the engine (generator end) the subsequent friction cause a spark and ignition of the crankcase gases, the engine was destroyed in this event and it was envisaged it could have been saved if it had valves fitted to vent the gases in a safe way.
as seen in the previous blog, there was damage around the liner seal lands....with this damage present on the liners it was suspected that this would be present on the opposite surface of the engine block, and after climbing inside the engine to get a good look, its confirmed that severe damage is present. This damage would see the block written off by BR, and a new engine fitted (if authorised) obviously we dont have that luxury so we need to find a way around it. In the damage above you can just about make out the position of the 3 liner seals, and then the machined surface below it. What has happened is coolant has found a way past seals 1 and 2 and started to go to work on seal 3. This has occurred because BR did not use antifreeze, antifreeze (apart from not freezing) has the advantage of a corrosion inhibitor. However......BR kept corrosion at bay by using a chemical called borax, which was added to the water in the engine to stop corrosion. The other way BR stopped corrosion was by never ever draining there locomotives. The depot rule was, when temperatures were 2 degrees the locomotives were to be started and kept running for 2 hours.....every 4 hours....if the temperature was below zero....the locomotives were kept running! failure to do this meant blocks and turbo chargers would split and cause severe damage to the engine. In preservation though, that's not an option.....cost being the main cause and also idling engine without then putting them under subsequent load causes bore glazing, which then means the locomotive starts throwing oil out the roof. So in the winter locomotives are drained....and when you drain a locomotive, you allow oxygen in......and this is what happens!
Another damaged bore.
to resolve the issue, we are using Belzona 1511 which is a very expensive very high immersion temperature chemical metal, which has been applied to all the bores affected and will shortly be sanded back to bare metal which means the pits you see in pictures 1 and 2 will be filled and a water tight surface created.
Other areas of work are the overhauls of the heads, each head has been completely stripped down to the bare casing, for repainting, relapping of the valves, and replacement of the valve guides, which were all found to be worn beyond the acceptable maximum. Here we see one of the heads on a hydraulic press having the guides removed, each guide requires 2 tons of pressure to free it from he head.
A valve port after the guide has been removed.
An original valve guide
A valve guide port prior to cleaning
A guide port after cleaning
A brand new valve guide being inserted....the new guides are pushed home by a rubber mallet and a smear of loctite to hold them in place. the heads have all been very roughly primed to keep surface rust at bay, once the mechanical work is complete they will get a full repaint.
After the guide is installed kerosene is poured around it, to confirm that the guide is fully pushed home and fully sealed.
with the new guides installed the valves can be lapped with grinding paste, a corse grind is completed first using a sacrificial valve, and finally a fine grind is completed using the valve that will be installed in the head.
as can be seen, it doesn't get all the marks out, its just a case of making it as good as possible.
Thanks for reading