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Ruston Hornsby PB3 - Stage 1: Tear Down
This fine freezing weekend at the start of July, I had some time free
so got the RH up onto my work bench in the engine shed (which was a bit
of a drama - no crane and this thing weighs in at about 300kg!
My dream shop (the kind where you hear Ted Bullpit in your head saying
"he's dreamin") will have a 2 ton travelling crane. One day! In the
mean time I make do with the gravel & mud floor and the old chinese
engine lifting crane for this sort of work - it would probably be
easier to lift the engine by hand than push the damn thing through the
mud to lift it onto the bench. Anyway, enough griping - it is all in a
day's fun :). |
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This is the overall first
impression now that I've pulled a lot of things off. Sorry about the lighting in these photos, it is night time and the inside of the shed is lit with tungsten sodium lamps which make everything a bit orange in photos - nice to work under though (and they keep you warm in winter). I've got all the external covers off, and drained out the 50/50 oil and water mix from the crank case. I never realised that there was still some green paint on this beast until I saw the flywheel in this photo - green spokes. Dunno if it will be enough to match with a colour, but I'll give it a go. The engine is in surprisingly good condition inside - quite clean and intact. Now that the piston is out, the flywheels, gear train, tappets, valves and governor are all free to move and everything spins around smoothly. This is both good and bad news - now I have to decide if I'll completely take it apart or not. Might not need to do so. I always prefer not to - if it works dont mess with it. |
| These are the bits of the engine
on the tarp as I pulled it apart. Amazingly all the parts are
relatively clean inside and out and free of major corrosion. The carby
is full of rubbish, but the float moves and the choke valve moves
freely (in fact so freely it is on the tarp next to the carby! The little tap at the bottom of the picture was submersed in mud, but still works and after blowing out with air is ready to be used. The piston and big end are in fantastic condition, but see the more detailed shots later. The covers still had their gaskets reasonably intact - from the look of them they're cardboard impregnated with fibrous material - probably asbestos, but maybe not given they're not subjected to combustion. The bracket in the middle is where the magneto should have been. It is a loaf style Lucas RS-1. I've managed to source one from a local (kinda) junk shop from a Ronnie. I'll alter its drive to suit the Ruston. |
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This is very surprising, the
piston is mostly clean with no scoring and only a little carbon buildup
on the bottom where I guess it burns oil after stopping. The rings are free and in really good condition. The bore is similarly good - won't need anything more than a light hone. The big end bearing was a breeze to get apart and is in very good condition (see pic below). After pulling off the other bits I thought I'd have a go at removing the piston. On examination, it seemed the best course was to drive it back into the crank case - especially since I'd been able to seperate the big end from the crank. With the crank turned upwards out of the way there was plenty of room for the piston. I drove it out using a block of wood and my favourite BFH (a 20 oz ball peen hammer). The piston will require dissassembly and soaking in diesel to clean it up nicely but probably not much more than that. The little end seems good - feels ok anyway, I've not tried to get it apart yet. |
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 These are the crank journal and big end bearing. They are both in really good condition. There is sign of slight marking along the centre where their was either some grit or not quite enough oil getting in. The bearings a so unworn that I suspect this engine has done very little work. |
 Inlet valve |
 These shots show the two valves open and close when turning the flywheels. I was pretty worried about the exhaust but apart from the angry spider (who's web you can just see) there is nothing in the hollow behind the valve. I was concerned that the stem would be wasted away and rusted and probably locked up tight in its guide, but no it was all good. |
 This is the exhaust tappet - a shiny bit! I'm very lucky that enough oil stayed in this area that this tappet is not frozen solid. There is some wastage and pitting on the shaft, but it is so thick that I don't think it will be an issue. |
 The butterfly is full of crud, but apart from that is in remarkably good shape. The mechanism is free and seems to seal ok. |
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 These two shots show the governor weights on the timing gear and the cams on the shaft from that gear. They look pretty ugly (so would you if you'd been imersed in a 50/50 oil and water mix for years). The gear teath are all fairly sharp and clean, does not seem to be any damage on initial inspection. I'll give it a pressure wash inside and see how it comes up after that. |
The next step will be to clean the engine and parts inside and out then decide if the guts need to come out or not. If they do, then at least one of the flywheels has to come off, but if they don't then great! So until next time...
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