1840 Hydraulic Issue

Hi,

I have an 1840 loader tractor with hydraulic PTO but no hi/low. The power steering works fine all of the time but the loader chatters heavily when lifting and lowering and tilting the bucket. The rockshaft also chatters on idle but not so much at higher RPM. The loader is correctly plumbed into the high pressure line and returned to the filter housing.

This chatter happens instantly upon starting the tractor cold and does not get any better or worse once up to operating temperature. The lift capacity of the loader seems to be unaffected by this problem. System pressure measured at the rear remote is 2250 psi and drops to 1000 psi when lifting the loader. The front reservoir seems to be filling with oil and the transmission pump supplys a steady full hose diameter stream of oil into a bucket with a front low pressure line removed.

Hydraulic oil has been changed, filter changed, suction screen removed and inspected but found to be very clean. Front pump removed disasembled and inspected. Replaced stroke control valve, 8 outlet valves and all o rings. Inspected steering, rockshaft, and control valves for hot spots but nothing really seems out of the ordinary.

Any help would be greatly appreciated.

Don't honestly know, but, it sounds (if I read what you are saying correctly) like you have some air in the system or a leak. HTH

How old are the hoses? Is there one unraveling
and partly blocking flow? Any quick connects with
problems?

I did not even consider the hoses because I was seeing some chatter in the rockshaft too. I will verrify now by hooking the loader hoses up to another tractor and testing.

Thanks for the suggestion.

Hard Knocks
I would like to compliment you on your diagnoses & explanation of your tractors hyd problem.

Are line clamps(parts keys #2,3 & 7) in place and tight? When you state R&R stroke control valve did you replace the SC valve seat also??
I feel confident you checked the small hyd filter in the pump during pump dis-assembly.

Thank you for the compliment Tx Jim. I believe that the clamps you show are the ones under the right side foot rest. They do seem to be tight and in good shape. Would that cause an issue if the clamp was loose?

I did remove the pump filter before removing the entire pump to check it's condition. It was very clean.

I did completely dissasemble the entire pump head including the filter. I replaced all of the seals including the two on the filter. I did also replace the stroke control valve and seat as I suspected that my issue was the stroke controle valve. The pistons were clean and in good shape with no broken springs, the intake valves operated but I did not remove them, the outlet valve disks showed slight wear rings so I replaced them. I replaced all of the orings and seals. I installed a new drive coupling rubber insert and reassembled.

I think that I might replace the flex line going from the top of the pump to the reservoir with a clear braided line for observation purposes. I don't think that supply oil is the issue because the chatter starts instantly. I would think that a supply issue would give me good performance until the reservoir runs out of oil.

I am very puzzled with this one. I keep wondering about an internal high pressure leak at the rockshaft but I would expect that to be one heck of a leak???

I think that I missunderstood what you meant about hoses. You were talking about the hoses at the front connecting the reservoir and cooler were you not? I replaced one of them due to being hard and not wanting to come off when I removed the pump. I will now replace them all. I am going to install a braided clear line from the top of the pump to allow me to see the oil or lack of in the system.

Thanks

The clamps for the lines that I was referring to at are the lines on RH side of engine oil pan.

(quoted from post at 09:33:46 09/04/12)
The clamps for the lines that I was referring to at are the lines on RH side of engine oil pan.

Click to expand...

Ok, thanks. I will check that out tonight.

Thanks

(quoted from post at 10:21:49 09/04/12) Would that cause an issue if the clamp was loose?
the intake valves operated but I did not remove them,

Click to expand...

Loose clamps can cause vibration of lines which can sound as if the noise is coming from a different location. The inlet valves could be the problem if not seating correctly.

I see where you are going with the clamps and will verrify them. This is more than a noise though. The loader chatters badly enough that it has left witness marks on the cylinder rods about 3/4" apart all along the length from the previous owner useing it the way it is. It also shakes the entire tractor when using it. The rockshaft chatter is also very visable when it is lifting.

Thanks

(quoted from post at 12:57:03 09/04/12)
I see where you are going with the clamps and will verrify them. This is more than a noise though. The loader chatters badly enough that it has left witness marks on the cylinder rods about 3/4" apart all along the length from the previous owner useing it the way it is. It also shakes the entire tractor when using it. The rockshaft chatter is also very visable when it is lifting.

Thanks

Click to expand...

I think your next step will be to check "flow" with a flow meter.

Here is the update.

I have sidestepped the flow test as I don't have a flow meter (yet).

Installed clear braided lines from the front pump to the reservoir and from the cooler to the return line. As suspected there is not an oil supply issue as the lines filled instantly and do not empty at any time. I have now also replaced all of the rubber lines in the front as the reservoir to cooler line was replaced when I re-installed the pump.

Disconnected and capped the rear remotes and tested - Still chatters FEL and rockshaft.

Disconnected power steering and capped - Still Chatters FEL and rockshaft.

Next step is to connect the loader directly to the high pressure port at the pump but I got stopped because I don't seem to have a 1/2" JIC fitting. I will pick one up tomorrow and make up an adaptor hose.

TX Jim what or where do you suggest I get a flow meter.

Thanks

I haven't bought one in years. I Googled hyd flow monitors and this was one site.http://www.lakemonitors.com/flowmeter.htm. Here's one on Ebay item 360453379991

How about a line direct from the front pump to a
pressure gauge and restricter valve. Return the oil
direct to the trans sump via the fill port.
This should narrow down if the pressure spikes
are from the pump or from the loads/control valves
?

(quoted from post at 04:12:01 09/06/12) How about a line direct from the front pump to a
pressure gauge and restricter valve. Return the oil
direct to the trans sump via the fill port.
This should narrow down if the pressure spikes
are from the pump or from the loads/control valves
?

Click to expand...

I think that is a good plan. I will try to get the fittings today and make up a test hose.

One thought for you experienced JD guys. I have the 34 PP1 pump head with the crankcase outlet valve. I do not have special tool JDH 19C for checking valve shimming. I just put it back together with the same shim washer. Would an improperly adjusted crankcase outlet valve cause irregular output flow like I am seeing?

Thanks

(quoted from post at 07:12:01 09/06/12) How about a line direct from the front pump to a
pressure gauge and restricter valve.

Click to expand...

b&d
I'm curious as to what type restricter valve you would recommend using for "your test"???????? "Your test" will still not accurately measure flow without the aid of a flow rater! ! ! ! ! ! ! ! ! ! !

[/quote]

Anyone with any experience with the question above? I am wondering what the symptoms of an improperly adjusted crankcase outlet valve.

Thanks!

Hard Knocks
I can't answer your question accurately because it been too long since I studied hyd diagnostics that closely. Maybe some of the younger techs will respond.

(quoted from post at 04:14:16 09/11/12)
Hard Knocks
I can't answer your question accurately because it been too long since I studied hyd diagnostics that closely. Maybe some of the younger techs will respond.

Click to expand...

Thanks Tx Jim,

Your help is very much appreciated!

I figured that I would give an update to help anyone else who is having the same or similar issues. So many threads just stop without giving the final outcome.

I disconnected the loader supply and return lines and hooked them up to another tractor (2120) to verrify the condition of all of the loader components including the lines, control valves, and cylinders. The loader worked perfect.

Next I ran a line direct from the hydraulic pump outlet to the loader supply line and reconnected the return to the filter housing. The loader once again chattered. As another step to eliminate the posibility of a return restriction, I disconnected the return line from the filter housing and removed the quick connect fitting. I then placed the line into the hydraulic oil fill port at the rear of the tractor and tested. The loader still chatters.

I can now conclude that I still have a high pressure pump issue as I have eliminated all other tractor components.

I have ordered a new crankcase outlet valve, seat, and spring, as I did not replace these before. I have got to think that this is an issue with the pump head controlling the flow rather than the pump. The pistons and valves were in great shape when I was into the pump a few weeks ago. I just wonder if I missed cleaning a piece of contaminant out of the pump head that is messing with the controls.