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Mike Adams

dismantling J2

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Hi

I am dismantling my J2 in situ and have come across a number of problems. When I took the gearbox off it left the shaft and cone clutch stuck in the forward position. Any suggestions how to free it off (it's been stuck in forward for about 30 years as the gearbox wasn't used. Also the whole thing  is a bit lose on the crankshaft.

I am just about to remove the pistons. What position should the crankshaft be in when I do this and should I pull the bottom of the conrod through the starbord door or let it drop to the sump. Lastly is there any issue with removing the cylinders other than access to the retaining nuts inside the crankcase?

Thanks

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For the clutch, heat and violence. It's probably rusted in

 

Can you detach the shaft from the cone?

 

Richard

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Thanks Richard

I think the shaft unbolts from the cone but I am not sure if having done this you can detach the forward clutch from the crankshaft without removing the cone first. I am finding the instruction book rather thin on dismantling the engine. I am trying to strip it down to the crankcase and get the bits out through the sidedoor

Mike

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Wot Richard said about the cone.  The cone bolts to the shaft and IIRC the nuts were well peened over. Try a big slide hammer on the end of the shaft.  If the gearbox has had oil in it it should not be rusted in.  Is it a lined cone or an unlined pair?  The unlined ones are renowned for sticking in gear.   They are also a two-piece female cone.

 

If you can get the shaft off you should be able to get at the ring nut in the centre of the female through the hole in the male cone.  From what you say this might be loose so easyish to turn.  Once the ring nut is off if it is all loose then it will just go backwards off the crank.   If not drive in one tapered key either side and that will make it looser.

The con rods come out through the doors on the fuel pump side, not into the sump.  You need to manipulate the crank so the balance weight is on the cam side with the  crank horizontal then remove big end bits and  lower the piston etc pulling the big end outwards. Once the skirt appears adjust the crank so it just clears the skirt cam side and the piston will then come down and be sitting on the crank web so that it can be withdrawn.  Take care of the crank as the big end comes past it and of the rings as you pull the assembly out.

 

The back piston is slightly easier than the front, cos there is a little more space. so might be a good starting point.

 

Replacement is the reverse of removal, but you need to fiddle a bit to get the rings to engage with the liner taper!

N

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Once all the pipework, nuts and locknuts are undone (9/16 BSF,  6 per cyl) the cylinders lift off.  They weigh about 23 Kg each so good body positioning for the lift is important.  Leave a couple of long head studs in, to use as handles.  They only have to go up about 3 in then can be twisted to rest on the crankcase.

N

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Thanks for the help. Pistons now out in a couple of minutes. I am now looking at removing the cylinders. I initially thought the studs went from the crankcase, through the cylinders and through the head. I see that ths is not the case and that I need to undo all the bolts in the crankcase which may take a while as it is quite difficult to get at. They seem much too tight to have been done up with an ordinary spanner. The clutch is unlined so I might have to improvise some sort of slide hammer to dismantle it. I am reluctant to take the shaft off the cone since the nuts are peened over but the cone is quite loose on the crankshaft.

Mike

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The 4 studs on the sides are OK with a short extension and a suitable socket.  They are nuts and locknuts but whether the thin  nuts are on first (as they should be) or second is anyone's guess.  Have a ferkle and try to remove them one at a time.  If not the studs often come out  with both nuts  and that is OK.

The front and back ones are a bigger.  There is not room for the stud to come out with the nuts on so the nuts have to come off.  A crowsfoot spanner on  a long extension down the cylinder our the best tool.  Otherwise a shortened  OE spanner and a hammer;   or a socket, two universals and a selection  of extensions is the the way.

  If all else fails remove the Y bolts and drop the crank and main bearing housings to get more room.  The problem may be  getting at all the Y bolts with the cylinders on.

Good Luck.

 

 

N

 

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6 minutes ago, BEngo said:

They are nuts and locknuts but whether the thin  nuts are on first (as they should be) or second is anyone's guess. 

<OFF-TOPIC>

 

Another famous can of worms, that last time I saw this discussed was in the Model Engineer magazine where the highly respected correspondent who had been arguing for years for lock nut then main nut switched to main nut then lock nut

 

Richard

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It's lunchtime and a bit cold out on the canal. However one is off and 5 bolts on the back cylinder now removed just stuggling with the centre one at the front of the back cylinder. Thanks for the tip of going down the cylinder - I had't thought of that!

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You are doing well.

 

There is a Kelvin special tool for this job.  I have seen sketches, but I suspect that the only place you will see one in the flesh is at Seaward.  It is a long vertical T-bar with an OE spanner welded on the end at right angles to the bar.  At the right height on the bar is an eye which fits over the head stud above the cylinder stud being addressed and which rotates on the vertical bar below a collar.   The clever part is the spring which fits over the head stud below the eye and allows you to push down and relocate the tool on the next set of flats without having to support the weight of the tool

I keep promising to make one but if not careful its a case of spending more time making tools than using them.

 

N

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I have now sorted the cylinders the last nut was the most difficult but eventually I used a 1/2" drive socket mated to 1/2 drain plug remover which had a 19mm hex to which I fitted a 19mm crowsfoot coupled to my 3/8" fine angled ratchet. I have now removed the clutch by sliding an old propsfaft coupling onto it and using it as a slide hammer, the nut of which was very loose, probably accounting for the slack I had In the forward and aft movement of the crankshaft. I have never seen such a strange arrangement using two sets of tapered wedges to hold the clutch onto the shaft. With these removed the cluch is very loose on the shaft so I may have to  think if this can be re worked or something. I have also removed the flywheel and tomorrow I hope to remove the timing gears and case which should leave me with a lump consisting of the crankcase and crankshaft that I should be able to get out through the side door.

 

Mike

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The clutch is meant to be like that.  When you fit the lead stops and drive the keys in it all tightens up nicely. The lead stops are vital, both to fitting it properly, where they hold one key in place so the other can be driven in tight, and to removal where the key stop deforms to allow the keys to separate.

The ring nut and it's shaped washer should butt up against the ends of the keys to stop it moving.  It is important to do the nut up dead tight so it doesn't all come loose like yours.  Stud lock helps.

 

N

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Is there a special spanner/tool to tighten this nut or do I need to make one up from scratch or does one just use a flat punch and a hammer. I noticed there are not any references to torque settings  anywhere. I could make up a bit of steel tube with some notches on the end to fit the tabs with a large nut welded on the other end and fit it over the shaft and use a torque wrench. I didn't notice any shaped washer athough the nut itself is shaped and clearly fits one way around.

Mike

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I have always used a brass drift and a 2lb hammer, with the flywheel on. Your idea of a piece of suitably shaped tube is a good one. Torque setting would be about 5 white knuckles or the equivalent of 'dead tight'.  Nut is a BSP size IIRC.

The washer is round on the outside and has a hole the same shape and size as the end of the crank.

 

N

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Thanks for the help. I am now down to the block and crank. The only problem I have found so far is the idler gear bearing being shot! Not sure yet how it is lubricated but no  doubt I shall find out. The main job now is to lift the crankcase out. I recon if probably goes about 3cwt at a guess.

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The gear train is lubricated by the oil gallery.  The oil that doesn't get spat at the bearings flows out of the front end through a hole in the rear half of the timing case.  Under the hole should be a vertical pipe that conducts the oil to one of the intermediate gears.  It then gets flung off the gear to hopefully do some good.  A new bearing should be easy to source, but may take a while to turn up as it is imperial  dimension. Did you check the timing gears and flywheel flange for alignment marks?

 

I would guess the crankcase and crank at 4,-5 Cwt.  At least a three shredded wheat job!  I would not attempt to lift it without a crane, but you may be built like Geoff Capes.

N

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Yes all marked up and there was a pipe which seems to run down on to the crankshaft gear so the bearing must just be worn. Bearing in mind I don't think it has been overhauled since it went in in 1987 could be worse! I shall be using an engine crane which can be reversed using a counterwieght which has a capacity of 10cwt so that should be fine.

2 days work in end and thanks for the help. Putting it all back together will probably be a job for next winter but having the clutch loose and the timing wheels rattling probably made it sound worse than it is.

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Bet you are pleased the next steps can be somewhere warmer and I expect you cam now get closer to the bank in many places.

What are you going to replace it with?

N

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I have already fitted a second engine under the front deck  ( 55Hp Isuzu). As the boat has a hydraulic drive it was easy to do this keeping the Kelvin in place. I did toy with idea of keeping both engines but that would be a bit silly. A Kelvin really needs to be in an engine room with easy access from the steering position and room to work around it. This wasn't the case with this boat( replica Bridgewater Llittle Packet) and getting to the engine meant clambering along forty foot of boat and down a very small hatch and into the less than full hieght engine room, with lots of opportunity for an accident in anything other than ideal conditions. I can now make a careful inspection of all the Kelvin parts in the warm of the shed and take it from there. Maybe an engine looking for a boat?

Mike

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I don't think I shall ever have need for this engine. The question is should I try to sell it in a dismantled condition or put it back together and sell it. I suppose if someone wants to put in a boat they probably would want to satisfy themselves that is fine by taking it apart anyway to check everything.

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We would try and sell it dismantled - we bought it as a 'runner' but it turned out not to be ,  so we ended up taking  it to bits  and rebuilding it. 

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Any serious buyer would want it all apart anyway, it would be an advantage in assesing its condition. Just make sure you document how it goes together and every single part.

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