JCB 3CX Help

[Mark M]

Hi,
Just registered recently.
I wonder if any of you chaps can help me.
I have slight mechanical knowledge but no nothing about these machines.
I purchased a 3CX black cab 1982+ not sure of the exact year a few months back for clearing a bit of land/footings been going okay apart from Having to put on new alternator a month ago.
I have 2 no problems the first one is the boom ram on the backhoe is lowering slowly,I have been told probably the seals in the ram letting by and need to be renewed,is this difficult to do ?

The other problem that just started is leaking oil at the bottom of the backhoe where meets the kingpost,I noticed a large nut with a hole in it looks like a dipstick was in here oil is coming out of this hole,if I put my finger over it the oil comes out of the bottom hinge joint at the bottom of the kingpost/backhoe connection.
I am hoping not a serious problem,any advice/info would be most welcome.
Many Thanks
Mark

[jcb4cx]

sounds like you need a ram seal in the main lift ,you can put a tap in line and see if it still drops with it shut
and it would seem you need seals in the slew tubes too if its making oil so to speak ,you could drain some out of the slew box via the large nut underneath as a temp stop to the leaking
not the end of the world to fix

[Mark M]

Hi Graham,
Thanks for your reply really appreciated.
In relation to the seal in the boom ram is this a simple job to do myself,I have a understanding of removing the ram and supporting the arm etc.The only problem I could see was removing the ram nut/collar at the top of the ram looks quite large diameter ?

The other problem I have with the oil leaking, is this hydraulic oil or gear box oil ?
It leaks quite a bit and I fill a 2 pint jug with it running in about 20 minutes am I okay to pour this back in the main hydraulic filler tank so not to waste it ?

I removed the filler nut at the bottom of the arm after the oil came out it is still full to the top should this lower down if it's leaking ?

When you say seals, is this the piston head seals in the slew tubes ?

Cheers

Mark

[jcb4cx]

the ram nut and then the rod nut would be the worst part of the job , if you have the means of undoing these then its a job you could tackle yourself , the slew seals have gone and are letting hydraulic oil into the rack and pinion housing which has gear oil in , it is then overflowing out of the filler hole , i have never done these , but would imagine it to be fairly straight forwards ,four big bolts hold each tube on and one pipe to disconnect on each (i think)

have you looked in the downloads section and downloaded a manual



downloads.php?cat=5

cheers graham

[Mark M]

Thanks for the reply.
I did download the manuel the other day and looked through the section showing the removal of the slew tubes and feel I should be okay to do the seals on this.
It states an interesting bit about using the hydraulic pressure to break the seal on the tubes.

I will order a seal kit and give it a go, I will let you know how I get on, maybe take a few pictures showing the procedure and post them.

I looked through the manuel and listened to your advice, I think I understand that the hydraulic oil as flooded the gear box oil, this is allowing it to come out the filler plug I think !

This filler plug with the hole in it, is it meant to have a dipstick in it to keep an eye on the gearbox oil level ?
If so my one is missing.

Anyway thank you for your experienced advice.

Cheers

Mark

[jcb1968]

Are you sure its the boom ram, as it was the bucket curl ram on mine that affected the boom lowering by itself?
there is no dipstick the slew box filler, mine has a little spring cap on it, yours could be missing,
just replace the slew ram seals, and fill up with gear oil.
i wouldn;t pore that oil back in, as its now mixed with gear oil

[Mark M]

Hi,
Thanks for the reply.
Not to sure in relation to the backhoe lowering, I had someone come round and he said it was the main boom ram, it is interesting you saying it was the bucket ram on yours, I think I will do the boom ram and see what happens.
I did notice the other day when I turned the machine off I could hear a clicking noise from the boom ram as it was lowering down so I am hoping it is this one.

The digger I bought was missing the triangular backhoe lock plate, I was thinking this not being locked in position when the backhoe is not in use could be putting extra strain on this ram so could be this one, what do you reckon !

JCB 4CX said I could put a tap on it,but I don't understand this.

I have ordered the new slew ram seals so am hoping to change them the weekend.

I will let yous know how I get on.

Have you done either of the above, if so was it difficult ?

Regards

Mark

[jcb4cx]

mark , i had a new jcb that would drop the boom quite quickly , new seals were fitted in the ram but it continued to do it
so they sent the fitter out to put in more new seals in the ram , but first we put a quarter turn tap in line on each end of the two pipes and then onto the ram , the backhoe was then out stretched to full reach and the taps shut ,the boom never moved after 15 mins
opened the taps and it dropped ,showing the ram seals were good ,but the spool block had a problem ,it then went back to the dealer and was fitted with a new spool block

cheers graham

edit
this may help , you may find a better one with a bit of a search
http://www.youtube.com/watch?v=GCKVxjq_GIA&feature=fvwrel

[Mark M]

Hi Graham,

Very interesting what you are saying,I would hate to go through doing the boom ram seals especially not to sure what I am doing and the problem is still happening !

I take it the taps you are talking about are hydraulic fittings that screw on to the threads of the pipes and ram spigots/tails and by turning the taps off this keeps the fluid in the ram ?
For me to purchase these I suppose would be from a hydraulic suppliers ?

Is it also true to relieve the pressure in the hydraulic system before opening any pipes is to turn the Engine off from the ignition and cut the engine completely and then push the control levers on the back this makes it safe to undo the pipes ?
I know the above might be a bit of a silly question to some of you but want to make sure.

Cheers

Mark

[jcb4cx]

yes mate that is the way to release the pressure
with the boom ram it may pay to stretch the arm out straight and lower to the ground ,then remove the pin in the actual arm itself
you can then close the ram up to make it easier to get out ,then drop the pressure before removing the hose,s

we used taps like these http://www.ebay.co.uk/itm/JCB-HYDRAULIC-VALVE-TAP-/220552520353?pt=UK_BOI_Industrial_Tools_Construction_Tools_ET&hash=item3359f462a1#ht_500wt_1112

cheers graham