1971 JCB 3c MKII Servicing and Renovation

[acstechnology]

Hi Guys,

I'm new here, and super grateful for all the info I've already managed to glean from existing threads.

I've just bought, a very unloved JCB 3C MKII to work my land and have no experience at all with these things so I'm going on a steep learning curve

I've put up some pictures, so you can see the extent of my project and here follows a long but not necessarily extensive list of jobs:
1. Replace burst hyd hose on backhoe
2 full Service (I doubt this machine has had a proper service in the last 20 years or more)
3. fix problem causing the need for easy start
4. Repair / replace broken part; engine stop, cold start, all lights and switches, horn button, indicator stalk, hand throttle, Van body and windows, loader arms(welding), fuel filler cap, missing fuel tank door, hydraulic door hinge, wiper motors front & rear, loading bucket welding and blade, backhoe bucket collection as it only came with a damaged trenching bucket

As you can see I have my work cut out for me, but on a positive note, it runs, drives and digs, but I feel I am going to need a bit of help from you guys with experience and knowledge and would be super grateful

So now for a few questions:
1. I want to change the hydraulic oil and filter but do I need to buy 'JCB Special' Hydraulic oil, my local supplier can do me 25l for £40 and Im on a very tight budget
2. I need a diesel filler cap and would prefer to get a locking one, anyone know a part number or can i get a universal one to fit?
3. does anyone know if the backhoe on this machine moves side to side on the rail mechanically or manually?
4. did this machine have a heated starter or cold start reservoir? and what would you recommend as a replacement?
5. I've searched for the serial numbers but struggled because of rust etc and the engine bay plate is missing, I have the reg number is it possible to get details from that?

Sorry this has been a long post but this is most definitely going to be an ongoing journey

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[MrF]

There is some manuals for your machine in the downloads section, both operators and maintenance manuals, and they cover these topics in there, but yes they had a cold start system for really cold weather, and its similar in concept to using a sniff of easystart, plus there's a cold start button on the simms pump detailed in there that only can be pushed when the engine stop is fully home and the throttle fully open.
I have that style of pump on a engine I'm putting in at the weekend so useful to know for myself also... The later engine I'm taking out for different issues didnt really require any cold start assistance normally unless it was really cold, then I just used a tiny sniff of easy start for the first start of the day but that had the later dpa injector pump on it.

Your unknown lever is to release the hydraclamps which hold the backhoe pivot to the rails, so then you can slide the backhoe pivot along the rails, its in the operator manual but you release the clamps with it, then use the backhoe's own motion with the bucket on the ground to slide the pivot along the rails, then re-engage the hydraclamps in the new position.

Apart from that I run mine on generic iso46 from the tractor supply place up the road, and when you say the engine bay plate is missing, are you looking in the right place? on the 3c2 there is a tractor skid serial number on the original tractor frame near the sump on the left hand side and its often obscured by the grot that collects in that area. The other plate is in the cab itself to the right of the drivers seat flat on the top of the machine body.

Check here for the jcb resources they host on here, they're really useful to have, the engine manual for the 38dt and 4/98 applies to your machine also :- app.php/dl_ext/?cat=5

[essexpete]

What does the hydraulic oil look like?
Definitely check the cold start with the button before you tear anything apart. Is the engine spinning quickly on cold start?

[FOWLER MAN]

What does the hydraulic oil look like?
Definitely check the cold start with the button before you tear anything apart. Is the engine spinning quickly on cold start?

If changing the hydraulic oil you should be aware that the system holds 43 gallons, 195 litres. So be prepared for that when draining the old oil. If the oil is clear and clean you may want to leave it, water contamination will turn the oil white.
If you do need to change the oil you will also need to take out and clean the suction strainer. That is a washable gauze strainer which lives in the oil reservoir behind the plate under the cab step where you will alsofind the drain plug.
Changing the return line filter will be straightforward enough.
Hydraulic oil should always be drained and the level checked with all the rams closed as far as that is possible so that the maximum amount of oil is returned to the reservoir.
As has already been said cold starting is by means of the excess fuel device, just open the throttle and click in the button on the fuel stop lever on the injector pump, you will feel and hear it click in.
Fred

[Jeremy Rowland]

Hi Kevin and welcome you already have some good answers to your questions; a little bit more to add for you; firstly you don't need expensive hydraulic oil just the correct grade, secondly as for your cold starting problem, I have copied your picture and labelled it, the No1 on the label is the cold start button, push this in, it should click into place and your engine should start easily. Second thing I have noted is that somebody in the past has been messing with the fuel injection pump because they have had the cover off and fitted it back on upside down (not that this should hurt anything) perhaps they were trying to either free off the rack or put some oil in there?
You may need to jamb the throttle down to get the cold start button to stop in, the one on my Hymac I need to put a bit of throttle on before the button stops in but she will always easily fire up once the button is in. hope that helps.

Jeremy

[acstechnology]

Thanks everyone, I downloaded the manuals, but your help in finding the button was brilliant and with a new battery the old girl just fired straight up without a struggle. So I guess these 3 can of easy start I ordered can be shelved until winter

I've replaced the burst hose only to find another leaking, so I'm not going to drop the oil until I've fixed all the hydraulic leaks as this oil isn't cheap. The hydraulic fluid is quite milky in colour when it spewed out the burst hose and considering its supposed to be changed every 1600hrs I figure it can only be a good thing to replace it... thanks for the advice on ram positioning by the way, thats a good one to know.
Quick question on this when cleaning the suction filter, do I need to buy a new gasket, as Im struggling to find one, is it a dealer only part?

I've yet to move the backhoe position, as I need to fix all the hydraulic hoses 1st, but useful to know for the future.

Im going to look at a cab this week, with a view to combining the good parts of each into one good cab.

Thanks again for all your help

[essexpete]

You may find it starts OK in the winter especially with a good battery and starter.

[MrF]

Excellent on the button, I wonder if they should have a actual button on there but both of ours have degraded and fell off.
if you cant find one, its easy to get some gasket paper and make one yourself with scissors and a hole punch. It only takes a few minutes and having sheets of the proper gasket paper around is handy. You can use the ball of a small ball pein hammer and gently tap the paper or some cardboard onto the flange and it will leave a clear impression to cut round/out.
If I'm feeling really professional, I draw gaskets in cad and cut it on my cheap chinese laser cutter, but not for a gasket I'm only ever going to need one of, for one off scissor cad works great.
The 3c2 I just disassembled had that gasket daubed with rtv where the last person to clean it out didn't have the correct gasket either. I'm not a big fan of lots of rtv...

[Matchless?58]

You will find that you are in for the long haul now . These machines do always tend to drip a bit , as fast as you fix one leak another one seems to start up . Or there will be something else that needs fixing if you enjoy tinkering around with old bits of machinery you will soon be hooked then there is no escape ! Most of these machines are slightly knackered a bit incontinent but still capable of a good days work just like me and the one I own . Welcome to JCB ownership great bunch of people and good advice on this forum cheers Chris

[acstechnology]

Thanks, I need to fix the stop button cable for the cab so I'm thinking I may look at designing some way to mechanically press the cold start button from the cab too.
I totally forgot about gasket paper, did think about a tube of instant gasket, but similar to you wasn't to keen on that idea. been a good 20 plus years since I tinkered with engines and gaskets. great advice thanks.
I now having issues keeping the engine running, its started just cutting out after a few minutes, feels like fuel starvation, so Im going to start with checking for air in the system as I believe this was mentioned either in the manual or another post, the previous owner also mentioned the fuel gauge may be reading incorrect.

Thanks Chris, I do enjoy a good challenge and am certainly enjoying the steep learning curve with this old machine, If I hadn't bought her she'd have gone for scrap and that would have been a real shame. Its a huge relief to know there are so many good people on here prepared to give up there time in sharing there knowledge to help out an enthusiastic student

Thanks again
Kev