JCB 1400B hydraulic pump rebuild????

In an effort to solve the problem... I am torn between the idea of

#1 SEARCHING for a hydraulic leak/bleed through in the valve bodies somewhere.

or #2 simply doing a main pump rebuild, it is a cummins motor, and the pump appears to be a simple gear pump.

Do you guys feel that a pump rebuild is a super major job or relatively simple (not counting taking the pump out and re install). I have no problem with the take out and re-install, I am only curious about the complexity of doing the pump rebuild.

Do you think that there is much to go wrong with a gear pump? or do they either work or not work at all? it is a double pump, ie there are two outputs P1 and P2.

Thanks in advance

Mike

In the meantime I can email you a few pages from this one, there is a complete schematic of the entire system for your SN range. I don't see the extradig cylinder on it though, but is shown elsewhere in a global illustration. But most of it looks pretty similar to what I have on my machine (a 311,515 SN). They also mention a hose burst protection valve and stabilizer check valves etc. Quite a few gizmos to go wrong, it would seem. Anyway, let me know what your email is and I'll try to get at least some of this scanned for you, and again in the meantime keep looking on ebay. Don't pay the dealer $400 whatever you do!

I have done a lot of work on this machine so far, when I got it it was in bad shape, I had to re build the 4x4 planetary drives, the extendahoe was snapped in two, I've repacked most of the rear end cylinders. I had to completely re pipe the rear end hydraulics, the documentation I have is for a series that is slightly later than mine, this makes it tough to know if I have the hydraulics piped ABSOLUTELY correctly.

I am suspecting that I either have

1)pressure bleeding through a broken seal somewhere
2)An improper functioning relief valve or spool
3)Pump malfunction (intermittent)
4)Improper piping to the extradig valve

I have gone over and over and over the hydraulic circuits in the book that I have and can see nothing wrong with the piping curcuit (the way I have it , but would not bet my life on it) The hydraulics are only producing about 1200PSI, I had a JCB service guy out here and he checked the MRV on the loader valve body and that was it, he had to go and charged me $350 , $250 of which was travel... I disassembled the MRV off the front loader valve and all passages/poppet seem to be fine.

I wanted to know if the pump was either go or no go ie; if I have 1200 psi, and actuation with minimal pressure on all axes, does that mean that the pump is ok OR Can the PUMB be WEAK? The low pressure in the system prevails 90% of the time and once in a while it kicks in (10%) The low power is evident as the out riggers will not pick up the machine and the hoe main boom can not be lifted when extended. However when the power kicks in everything works with full power. The lack of power is present in the loader as well.

I guess I feel the same as you about tracing the circuit and understanding the flow circuit, BUT certain individuals KEEP TELLING me "it's the pump" I dont think they really know, I think it's just the most convienient diagnosis.

Do you know where I can get a manual for this machine without spending a fortune? S/N is 322826 and it's an 1987 machine.

Very curious that the JCB neve put a cummins in.... everything looks factory style, I don't know the machine's history, but I'm bound and determied to get it running right... any ideas? ps, I'm not a hacker, I care and have respect for the equipment even though the person before me obviously did not.

Thanks
Mike, Barrie Ontario

And you can get manuals for these models on ebay pretty easily. Lots of people selling cd's and hardcopies. I have an operator's manual for the 1400/1550/1600/1700 series and it has the hyd circuit on it. If you need a scan or two let me know and I can send it to you. If you post the whole SN of your machine I can also tell you what year you have as well (alot of people get the year wrong on these models for some reason).

Good luck, let us know how you make out.

The year (as far as I have been told is 1987) serial# 322826. NOW I thought too that I could get a manual, and yes there are lots for sale, BUT NOT FOR THIS SERIES. I can not find the various piping prints, this is what I want to verify first, even from a later series would be fine because there may be similarity enough to validate the routing of the hoses, the "person" who had it before me had COMPLETELY DISCONNECTED THE ENTIRE back end hydraulic system, because they snapped the extra dig in two pieces. I rebuilt it, repacked the cylinders and re piped the rear end, everything moves but no real power, I only have 1200 or so PSI. So before I go too crazy, I want to somehow verify the circuit piping, the tips are that it has NO separate Unloader valve, It has a "Y" pipe on the return line, it has an extradig separate valve AND the pump has both P1 AND P2. If you have some piping drawings, please send them to me I would greatly appreciate them, a drawing of the entire circuit would be great, I have a JCB manual, but it does not contain the piping confugurations.

Big J is giving me some expert advice too, he used to be a JCB service manager, once I told him that I wasn't a hack, and that I had actually put some effort into it already, he seemed willing to help me.

Thanks Seann, regards

Mike

Anyway, I do have a manual on its way that starts at machine no 290,000. When I get that, I'll look it over and see what it has in it. I'll try to compare what I see in the older one to the newer one and let you know of the differences. If it comes down to it, I'll scan images from the older one and send them to you and/or send you a copy of the cd I have. I'll keep you posted when I get the new (old) manual.

Keep me informed.

Thanks so much

How do I analyse the presence of cavitation?

Not so bad news, in haste, I mispoke, it is infact a Perkins, NOT Cummins, don't know why I said Cummins other than thats what jumped to mind.

I will get the pump serial #, but I think the first thing I need to do is to verify that it is not a simple piping circuit error, If I have repiped it improperly after the other guy, disconnected everything, then P1 could be fighting P2, P1 is currently going to the main front loader valve body and P2 is going to directly to the extradig valve, out of the extradig valve then to the hoe valve body, this seems strange as P1 also feeds the hoe valve out of the main front loader valve. This is why I say that I think it is so important for me to first absolutely verify the piping circuit.

I did my best to piece together the information regarding piping, bits and pieces,, the only distinguishing point of all the piping circuits that I could see is a Y pipe on the taqnk return line, that drawing is what I based my piping conclusions on.

What seems irregular on my machine is that there is no separate unloader valve, I believe that it is incorporated into the main front loader valve with that controls the front bucket.

The machine serial # is 322826, year 1987 , options, 4x4/Turbo/extradig. Hoe Swivel is via the two large bore cyliders at the back/bottom. I have searched the ENTIRE WEB for a manual for this series, lots of manuals after this. I have no problem reading prints, but a simple isometric or piping diag is what I need...

Can you get your hads on a manual I can buy off you?

Thanks for the help..... Mike Hamilton.

I've checked all the EBAY manuals, they are ALL of the higher serial number, I have the actual JCB manual for the higher number.

There is no book available anywhaer on the web for my series of machine.

Even though my book is an authentic JCB manual, Nowhere in the book does it indicate how the piping circuit is ROUTED TO THE Valves, this is because there is no similar confuguration, as I said my machine has no unloader valve.

Let me ask a question... CAN I DEAD HEAD THE PUMP to validate the pressure or will it damage the pump?

My thought is that I isolate certain parts of the circuit by dead heading, BUT I DON'T Want to damage the pump. What do you think about this?

Thanks
Mike

ps Think I'll just buy the correct manual for my machine for the $400.

I dont have an adjustable flow control valve but I do have a pressure guage, I measured this morning, off the front main valve which controls the loader and is fed by 1, I got about 500 psi when raaising the bucked idle, I got about 1200 psi while raising the bucket whaile at higher idle, the pressure jumped to 2000psi at high idle when the bucket hit the full extension point. I don't know what to conclude....

Instead I found a machine near by with the same set up and have now validated the piping is correct. (remembering that when I got the machine the Extra dig was snapped in two and the entire backend was hydraulically disconnected.

I will re verify the pressure indications tomorrow. I plan to measure at medium and high rpm, during actuation and monitor what the pressure jumps to when the cylinder is fully extended and pressure going over the MRV.

I will check pressure on both the front loader (main fed from P1 side of the pump) valve and at the extra dig valve which feeds the main hoe valve body off of the P2 side of the pump.

Yes the machine needs grease, but, I have also seen the thing KICK IN!! and its like a whole different piece of equipmnet (like a new wife or something, although I wouldn't know about that). I can't say what causes the hydraulics to kick in othere that it seems to do it when the machine warms up but only on occasion.

-JRV says that the pump either works or doesn't
-Another individual indicated that there are "O" rings in the Extra dig valve (which feeds the main Hoe Valve) and if the "O" rings are gone, I will get tons of blow by I feel better now after doing the A/B piping comparision to another machine.

I'll report the pressure readings tomorrow, too dark to work, although I am keen to invest the time move closer to the problem, I think my pressure readings were off from earlier, I will validate them tomorrow. I like the Idea of the flow calculation, but, the cylinders may throuw the calculation off if the seals are a little worn... no? The point I'm trying to make is that when she kicks in it seems to have just incredible amounts of increased power, the difference is not minimal.

If JRV is correct and he worked for JCB, the pump being a gear pump is fine. I need to go with his experience on that and assume that the pump is good for now. Then I can concentrate on the pressure readings and after that, I would like to start removing valve bodies and checking them. I have already completely disassembled and checked the MRV on the front bucket valve body, It seemed fine, but I suspect that I am NOT getting the 2000PSI I indicated earlier I think, I'll find more like 1200-1500PSI when the cylinder is fully extended. I am assuming that the MRV is the one on the front loader valve. Strange thing about this MRV, I turned the Allen key adjustment on top while the cylinder was maxed, and did not see a pressure increase/decrease that I expected to see.

Thanks to all,