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JCB 3C111 Heads or Sumps?

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 fuel 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.

Mark
June 2009

JCB Vehicles, Tractors

This is extremely generous of you, I shall be very pleased to do so.

Mark
June 2009

Hello
This page is getting rather full. Would you care to text an email address to 07791349306 and continue by that means?

Mr. Toad
June 2009

Thank you once again.
I shall investigate the damage more thoroughly, and see how I get on with that approach.
Best regards

Mark
June 2009

Hello Mark
I'm certainly not going to say "I told you so"!
Firstly, from here, it's hard to see how bad the scoring is. However, it may be worth trying to give it a clean up with a strip of fairly fine emery cloth, as the scoring may actually be metal from the bearing.
The play in the little end is likely to be a worn bush which can be replaced, rather than buying a new conrod.
Are the other big-ends damaged at all? If not, you could try fitting the shells into the rod already removed,(after cleaning up the journal),and fitting it to No.2. You should be able to do this from underneath. Feel for play in the vertical plane. However, this is a very rough and ready wear check, and does depend on what wear may exist on the "new" shells.
If you can detect play, then it looks like a crank grind(ideally, if scored as you say, it needs one anyway).
But depending on what you find and how the crank pin cleans up (don't take metal off!)a set of new shells may get it out of trouble, and may be worth a try. You will have to decide whether to spend money on new bearing shells all through, which may or may not provide a lasting solution.
Sorry I can't offer any more advice at present (subject to what I said above, though, I think I might try the easy and cheaper, option, shells, first!)
I'll keep "watching this space"!!
Fingers crossed for you.

Mr. Toad
June 2009

Dear Mr Toad
Sunday I removed the sump.
The accumulated muck in the bottom contained no sign of water, and was not nearly as bad as it had seemed when I removed the sump plug.
I un-bolted the bearing of the Conrod from No2 piston, and drew it up out of the block. The Piston, rings and barrel were all in remarkably good order. The bearings however were not. The big-end bearing had started to break down, and the little-end also had a huge amount of play.
I have removed and inspected (one at a time!) the central main bearing, and adjacent big-end bearings, and am visually unable to find any other significant signs of damage.
I have not removed all the bearings to inspect (as the front of the crankshaft is underhung by what I assume to be the oil pump assembly, and this obscures access).
Because there is some scoring to the journal of No2 do I assume that I am beaten?
I am tempted to just obtain a replacement conrod and bearings (the current ones are stamped US .015 ) and gaskets, and re-assemble the engine, knowing it to be wrong.
I assume that I should take the crankshaft out & have it re-ground. I am overwhelmed at this prospect, as it looks like I would need to remove the engine to do so, and the cylinder head alone was heavy. Furthermore without a workshop manual to refer to stripping down the block may well be beyond me.
I would welcome your experienced observations (although I feel an “I told you so” coming my way).
Best Regards

Mark
June 2009

Thank you once again. I have sieved my old oil tonight, and found nothing untoward.
I shall take on your thoughts about the bottom end, and shall drop the sump next to clean & investigate. I will be very pleased to keep you posted on my progress and findings.

Mark
June 2009

Hello again
Oil capacity is around 16pts. if I remember correctly. I suppose you could try flushing it out(diesel would do), but as you needed to poke out the drain hole to get the oil to drain it may be wise to drop the sump and clean the oil pump pickup filter screen. If you decide to go this far, you may as well drop the bearing caps(not all at once) to check their condition.
Re. piston height - a slight variation is possible, but a worn big end bearing could be the cause( top shell takes the greatest load) thus piston not being pushed up quite as far.
By stuck rings, I meant rusted to the bore preventing the engine turning, which you have cleared.
If the m/c had been last run in December (winter) perhaps the water was frozen, causing rapid overheating?
I'm afraid there is little more I can add at the moment.
If you have any more queries you are welcome to ask.
I would be interested to hear how you get on.

Mr. Toad
June 2009

Gulp!
I’m feeling angst again!
Real life honest advice, (this I understand, and thank you for it) but it brought me back into the real world with a bump.! Whilst I hear the logic of “ better to buy a working engine”, if possible I would prefer the old girl to have her original engine. Also I do enjoy to achieve a repair, taking something neglected botched & abused, applying effort and a few funds to restore new life is (to me) is most rewarding. I guess we all have our little idiosyncrasies.?
With that in mind I should like to try to proceed, if it is within my abilities. So I have further information / advice to request, if that’s ok.
1. I was informed that the m/c had been standing since December, and that it had “blown up” about 5 minutes after being started from a 2 year rest.
2. The oil level was not even registering on the dipstick when I first inspected the engine, I added 5 litres to bring it up to the correct level. I had to add around 2 litres of water to see the radiator full.
3. Despite the coolant in the piston cups there is no evidence of corrosion or scarring in the barrels. Each of the four pistons can be moved round in the bore, suggesting to me that the rings are not stuck?
4. Last night I removed the sump plug with trepidation, and nothing came out! Panicking I checked that it was a sump plug, it had a protruding magnetic central pin & was located where I would expect. So I inserted a long screwdriver into the solid crud & agitated it until the oil flowed freely.
5. Before leaving for work this morning I inspected the contents of my sump tray. The oil is (very) black, with no apparent emulsification. I may sieve it tonight to inspect for debris?
6. I checked the piston height in the bores, and number two piston does seem to finish a little shorter than the other three?
I do enjoy gaining the experience, but also appreciate your frankness as I do not wish to waste my time fruitlessly.
Best regards

Mark
June 2009

I seems the m/c has been standing for a while with water in the cylinders for the rings to have rusted to the bores. Is there any signs of damage to the bores?
Do all the pistons reach to the same height in the bores? I would be looking to see if a conrod had been bent if water had entered while running. What is in the sump? Oil, water, or greyish sludge(emulsified oil due to water entering while running). You need to have the cylinder head checked for cracks/distortion before grinding in valves. Your idea of supporting the engine for removing the sump seems ok. Firstly though, if the sump contains only oil(no water - drain it to see) I may be inclined to refit the head, having checked it, and give it a try. Without seeing it, it is difficult to give a more definite answer, as you may have damaged piston rings for example. Unfortunately, to do the job fully, you MAY be looking at a new head, pistons and liners, main and big end shells and perhaps even a crank grind, all of which would not be cheap. If this was the case, a good s/hand engine may be the easiest solution. If you where to go this way, you could try Lee Gregory (search "Digger Doctor") or Vicary Plant Spares.
I don't know any reason why the bearing shells cannot be changed with the engine in situ.
Sorry if I am not being very optimistic! I would rather you be prepared for the worst, than give you false hopes! But as I said, if what you can see looks ok. try it, you don't have a lot to loose.
Best of luck with the job!

Mr. Toad
June 2009

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