When home I tried towing it whilst in 1st gear, just to see what sort of noise came from the engine and thus point me at the head or sump for my first attentions.
All that happened is that the forward movement was accompanied by a Hypoid/Gearbox type of noise, with no apparent engine rotation.
As the gearbox drives from the rear, and the Hydraulic pump from the front, is there anyway to turn the engine over manually? (The starter clicks in and strains, but can’t move it, and I don’t want to burn that out too!)
Mr Toad, thanks to your excellent advice I managed the journey home last night. I wrapped the rams with some old carpet, then bound two 9” lengths of 3x3” angle iron over it around each side. I also made some 1” thick hardwood blocks to sit between the angle iron & the rams, to protect the seal covers. The steering was VERY heavy (and felt “notchy” when I was really heaving it) but it was manageable!
(I would be pleased to email you a picture of my version of your assembly installed & working if you are interested!)

Mark, in not so sunny Yorkshire, May 2009

Thank you for your advice again. Following your suggestions I calculated that the coolant level was about 2 litres below full. So as recommended I removed the injectors, and shining a torch into the hole could clearly see bright green reflection of a pool of coolant in the cup of the two raised centre pistons (the outer pistons were at the bottom of their stroke so below view).
I disconnected the hydraulic pump driveshaft at the crankshaft pulley, and found some bolts of the same thread to bolt in & use to lever with. A 4 foot long bar with me standing on it’s end would not budge in either direction.!
What to do next, Heads or Sumps??
My logic (but lack of experience) suggested that to be as seized solid as it was pointed at the bottom end, but the sump seems to be a cast lump that supports the whole engine. So, as there was evidence of coolant in the barrels, and also to reduce the engine’s weight, I stripped off & carefully removed the ancillaries, and then the cylinder head.
I emptied the cups in the centre of each piston of their contents of sludge, oil, and coolant. In the “hope” that the rings had merely stuck to the cylinders I decoked the crowns & sprayed copious release oil around their edges. I then made a hardwood drift to cover the entire piston face and proceeded to tap each one in turn. This, in conjunction with my 4 foot bar, and eventually I have her turning. I then redirected the cylinder head feed into a can, the feed from the pump into a jar, and had her spinning on the button.!
With all this in mind, and based on experience are you able to advise me on the following:
How can I tell if I must now turn my attentions to the bottom end?
Should I simply rebuild the top end and try it, at the risk of having to re-strip it?
Also I have never tried to replace a crankshaft’s bearings. Would this require specialised tools? And/or a workshop manual?
Can the bearings be inspected satisfactorily and replaced in situ? I believe I can fabricate a frame to sit across the loader arms and support the engine from above, however if the engine block has to be removed I think I may struggle.
I agree with your comments about spam etc.. but should you be interested in that picture I am mark (at) broomfleet dot fsnet dot co dot uk , I’ll leave it up to you.

Mark, June 2009

Hello
Glad to hear you made it! I told you the steering would be heavy!! The notchiness is the plungers in the Danfoss unit working without hydraulic pressure.
There are three ways you can try manually turning the engine:-
1. Put a bar into the pump drive UJ. from underneath, but mind you don't shear off the grease nipple.
2. Take off the starter motor and lever against the ring gear teeth. Carefully!
3. Disconnect the pump driveshaft at the crankshaft pulley end and apply a suitable socket or ring spanner.
Is there any water in the rad.? If the head gasket has gone there could be water in the cylinders, "hydraulicing" the engine. Try taking out the injectors, then see if it will turn.
All good fun, eh?
ps. Don't think they let you put email address on here, leaves one open to lots of junk also.

Mr. Toad, May 2009