JCB 3CX Sitemaster - several questions

[ady-uk]

Hi, I'm a member, but not new to diggers.
My dad who passed away recently owned several diggers (JCB's and rubber ducks) and was owner of Solihull Plant Hire in the Midlands.

Anyhow long story short, I've been able to drive all his plant since a young child and use to help him fix them too. We've kept the old 3cx Sitemaster as it's still required for use on our farmland. Which I generally look after.

Here are my questions.

1983 JCB 3cx Sitemaster, 2wd Perkins engine, white cab.
No 301624

1. It has developed a leak at the bottom of the king posts, which would appear to be the slew ram seals.
A - Can I order spurious seals or do you recommend genuine JCB?
B - What size are the 4x cylinder bolts, thinking I can get some all-thread sticks and nuts, to 'wind' the cylinder covers back on.
(or if I planned ahead and stopped the machine with the arm slewed fully at the side, couid I use the arm to push it on itself?
C - At the bottom of the kingpost, I can see the big drain nut underneath, but I can't see anyway to fill the gearbox (rack n pinion) casting with oil. I've looked all over it.
D - I guess you have to do both seals, as you'll never know which side has gone, and when draining the gearbox, you'd just want to do both anyhow. I'm guessing you still have to do just one side at time though?
E - When you assemble back together, is there a recommended gasket sealant, or again is JCB's own the only real choice?

2. In the engine bay, at the far side, behind the transmission dip stick, there's a filler cap (photo). It's this the transmission filler?

3. What is the steel disc cover in the cab floor. I can pull it up and push it down, it's held inplace with an R pin, doesn't seem to be anything you'd need to get to under this plate.

4. How full do you fill the hydraulic tank, due to the slew cylinders leaking, I've topped it up but not near the top, I guess as the rams are full of oil both sides, you can't really over fill it and then create a disaster by extending or retracting the rams (only mini disaster by filling too much is the oil getting hot and causing more volume)

5. The indicator stalk (side of steeing column) is all burnt up and melted, seem to remember it caused an electrical short. Is this conmon? I will look for a second hand one and replace it. (currently the fuel gauge doesnt work and think it may be related)

6. If I leave the digger parked up for a while, I'm talking a few weeks, both the rear stabilisers are on the floor. There never seems to be any oil leak. Is this normal? I guess the oil is slowly creeping past the seals over a long period of time, which isn't really a problem. Just wondering if they should hold forever.

[agrimax]

Hi Ady,Welcome to the forum.
Seals don't need to be genuine. Vicary Plant will sort you out but there's plenty of others supply them to.
Slacken the bolts (38mm)slightly and working the slew should break the seal allowing you to pull off the cylinders after removing the pipes. You should be able to restart the cylinders over the new seals and tap the cylinders back on with a sledge hammer and piece of wood over the ends. I've never had to use brute force to put them back on.
The fill point/plug for the slew box is down in behind the bottom of the boom where it pivots on the long pin.Should have a breather on top of it. You need the backhoe stretched out behind and on the ground to access it.
With the boom centred,remove and replace both sides of slew seals together.Any decent sili-gasket will do.
The filler cap you showed is for the engine oil.
Transmission oil is filled through the dipstick tube just to the right of the battery. Level to be checked with the engine running(or immediately after switching off) but if topping up,you need to give the oil time to run off the insides of the tube as the dipstick scrapes oil off the sides and gives a false reading.Either 10w or ATF can be used.
The steel disc is the heater vent.Up for cab heat and down for windscreen demisting.Switch is down on the left side of the dash console for the heater fan.
There's an oil level sight tube on the inner rear lhs of the hyd tank just left of the engine oil filler cap. Possibly no longer transparent by now. If you overfill the tank,oil will simply overflow out through the built in breather in the tank cap,especially if you drop the loader quickly.Just wastes oil and makes a mess.
You might find a second hand indicator stalk but I'd think they're scarce by now. New ones could be around £200 plus. Leyland lorries and BL cars (early Metros) of that era used the same switch. I fitted a 3 position toggle switch for the indicators on mine but the horn and main beam still work on the original stalk.
None of the rams should creep by right,but I'd expect there to be wear in the seals and valve block in a machine of that age. Probably not worth bothering about...

[gecko.cx]

Welcome Adrian,
the filler for the slew box is hidden above the boom pivot

It is very hard to pull the pots in square (resulting in damaged seals), so make sure they really need changing before you go down that path.If you must, Pretty sure the bolts are 1" UNF and allthread is how I'd prefer to do it, but couldn't get any.

If the machine has been out in the weather, water gets into the slew box, the oil floats, leaks and leaves the box full of dirty water.
Ease off the drain plug and see how much water come out. If you are lucky, that's all it will take.

I recently bought a seal kit from a JCB dealer, paid the OEM price and ended up with an INTERPART kit. Nothing wrong with it, but not what I was paying for. Try vicaryplant.com - they seem to be well regarded as an alternative uk parts source

The stabiliser rams should be able to stay in position. The leak could be the piston seals or in the valve block.
You could lift the leg and prop it on a jack. Remove the hydraulic lines and cap the ends. If the leg still extends, you know it's the piston seal.
If it's taking a couple of weeks, I'd live with it until it gets worse.

edit: beaten!

[Slooby]

Workshop manual is in the downloads section of the forum, along with a scanned copy of the parts manual (sadly no parts numbers, but useful exploded diagrams of everything)

JCB 3CX/4CX Backhoe Loader workshop manual

JCB Excavator Loader (1985) parts book

[ady-uk]

thank you both for replies.

i will get the slew seals ordered asap.
My dad owned it for at least 30 years and always been kept in that shed, so no water ingress.

prior to that we had JCB 3C mk2 with fordson engine, hardly done any work and never been on hire, unfortunately some low life knicked it. (we never saw it again) i knew my way around that digger inside out.
Quite an unusual mk2 (probably very late) as it has the shaped wing, where you get in, the sliding top door and bottom opening hinged half door, with tool box under that footstep. However it had the Fordson engine, manual gear lever between the legs and no 4in1 bucket. it was an S registration. I digress. when he first started he had a hydra digger, which broke in half, fortunately just as he was upgrading.

Confused about the reply regarding the engine oil filler, as i al ways thought that was down by the oil dip stick

pic attached.
circle 1 - I thought was oil
circle 2 - the one i asked, looks too far back to to go into the engine sump.

[agrimax]

The 3C Mk 2 used Leyland BMC engines,not Fordson, but the small opening half door into the cab came in on the Mk3.
I'm confused too...can't see any filler cap near circle 2. Maybe a rubber buffer that the bonnet sits on??

[essexpete]

Well you have some good help from the lads on here! One thing worth investing in for inner gland seals is a proper tool. Can be found on ebay for a few quid.

[ady-uk]

The 3C Mk 2 used Leyland BMC engines,not Fordson, but the small opening half door into the cab came in on the Mk3.
I'm confused too...can't see any filler cap near circle 2. Maybe a rubber buffer that the bonnet sits on??

sorry it wasn’t really late and i got confused.
Yes it was a Nuffield engine.

My understanding that didn’t make sense, is all the 3c mk3 i see, have power train, usually extradig too. ours didn’t.

i look at adverts to see if our old one appears as we modified it, drilled specific holes for home made bale spike frame, log splitter output etc.

[agrimax]

Yes,the first Mk3s still used the old 10 speed Nuffield gearbox or the Brockhouse torque transmission as used in the Mk2.Then came the 3x3 synchro manual box which was followed with the Powertrain torque unit in the last of them. I've seen a few Powertrains but most here in NI seemed to have been manual and extradig would be a rarity on any 3C in NI.

[essexpete]

I think the extending dipper was fairly rare here in SE UK on the 3C111. Quite a few early 3CX did not have extenders either.