JD 400 Backhoe pulsating weak hydraulics

[JimmyBOD]

Thanks JJ. I have saved the link. Very informative. I am going to drain the hydraulic system tomorrow and look a cleaning what I can and checking the lines to see where they lead. I'll blow them out with air and replace the old rubber lines. Put the fluid back to see what shakes.

 

[JimmyBOD]

I am thinking the same thing. There is a nut above the vertical filter near the top of the transmission that I drained the fluid from one time. I bet the part goes in there.

Thanks for your help.

 

[olde man]

while you're checking those rubber lines make sure that none are twisted or kinked

 

[J_J]

You probably should purchase a good manual for your tractor.

Your hyd system might have something like this.

Basic Hydraulic Fixed Displacment Pump and Acculator Closed Center System Schematic - Engineers Edge

I believe the accumulator in this situation is there to keep the system charged and to smooth out pulsations from the pump.

The pump will unload when pressure is achieved, and then flow goes to tank with no pressure.

 

[Leejohn]

that part looks like some sort of poppet possibly from a valve should be a spring somewhere in there also

I go long with what olde man said and I would stop doing anything and work on finding what valve it went in.

 

[Zebrafive]

The pump has a filter inside, part number R27173 might try changing it

 

[JimmyBOD]

I am convinced this problem is because of dirt, sludge and droplets of water in the hydraulic fluid.

I found the location that was missing the part I found in the tub when I drained the fluid. It went in the relief valve next to the horizontal filter. This relief valve has 3 parts that are listed as valves: 2 ea. of 40976 and an R-57559.

I put the fluid back in, but kept out 3 gallons that looked like it had droplets of water in it.

The tractor, hoe, bucket and outriggers all work fast and with power. Given the fliud has not reach a hot temperature yet, when it does, I might find, other problems.

It is very frustrating to have the tractor working like it should knowing I never did anything that I didn't do before. The only changes was leaving out fluid that looked suspicious. I have 10 gallons of new fluid that I had in the tractor and it didn't stop the pulsating or give it power.

What pulsating I had today was minimal. Wonder what tomorrow will bring?
Thanks to everyone for their help. It is amazing when people offer online advice and help me more than a JD mechanic can do when he has the tractor right in his shop for two weeks.

 

[olde man]

you're welcome, they should give those guys a class on working on these good old tractors that are still out there working. good luck with her.

 

[JimmyBOD]

I would be tickled if they would post online the parts and service manuals. As far as the comments on the Net from people like yourself, the thanks I could give isn't going to be enough.

I had the tractor in the dealership for two weeks and they only worked on it for 4 hours. That cost me $438 for changing filters and putting the old oil back in. Yikes.

 

[Gale Hawkins]

you're welcome, they should give those guys a class on working on these good old tractors that are still out there working. good luck with her.

I am not sure that is possible. Many who knew these machines are even dead.

OP I think there are only two good options on old JD's, etc from what I have learned messing with our 1976 MF 265 and 1983 JD 310B backhoe

One is to find someone with a shop out back of the house that can/will work on old tractors of the distant past.

The only other option is to buy the shop manuals off of E-Bay, etc and train yourself.

Getting the water out of your hydraulics could cost you a few thousand dollars perhaps using the dealership.

After loosing most of our fluid when working the BH with a blown O-ring at the transmission housing I drained out the remaining 1.5 gallon and the first think that ran out was nearly pure water then came the milky stuff.

While there I changed out the canister filters just to insure they were not
not clogged, etc. I that to refill to find the location of the leak by getting under the tractor with it running.

Then we moved it about 100 feet to get to a better spot to pull the valve body from the transmission case and replace the O-ring. While it was running I moved every cylinder two full cycles to try to get the new oil into the cylinders before draining it down again.

I was shocked when pure water ran out when I first removed the drain plug again. To me this indicated there is pure water in the cylinders and eleswhere that gets pushed back to the transmission case when in use.

Using alcohol in a proper manner I expect is the only way to get most of the water short of a total tear down of the machine.

After getting back home after being going for a week I want to get some hours on our new fluid and see if if the Sea Foam Trans Tune is going to help. The RENEW line of fluid from TSC is to deal with water better and soften the seals. We have put in 15 gallons of the RENEW version since O-ring failure.

After finding pure water on the second drain down I replaced the filters again thinking they may had trapped some water in the the paper. Cleaning the intake screen was very hard even after I found out how to get to it.

Only about 6" of the 12" screen tube would pull out and it was very clogged with lint like matter. With a lot of diesel and a 2 gallon pump sprayer with the nozzle removed I was able to clean/back flush the 6" section I could see and the remaining 6" section blind then we poured diesel into the fill hole (dip stick tube in our case) to flush out stuff that would have come off the wire screen tube. After that we then poured in new hydraulic fluid until the diesel changed into clean fluid coming out of the hole where the screen filter inserts.

Bottom line I think most old BH's have some water in the system.

In our even after a full drain down and refill 3/5 fifth of the old oil is still in the system because only 8 gallons of the 20 gallons will drain out of transmission case. Making sure most of the cylinders are NOT extended will help a bit I think when one does a drain down.

Keep us updated as you get more hours on the clock.

If I do not get the results I want from RENEW I plan to add up to four gallons of Lucas Hydraulic Booster if I can get the water problem addressed to a large degree.

 

[olde man]

those old manuals are like gold pending on the tractor i've seen them bring $50 and up for just one thin little manual at antique equipment shows

 

[JimmyBOD]

Thanks for all the tips. I can see that I need to do more to get ahead of this. I bought the tractor from a man who owned many machines. I doubt if he kept up wth the maintanence.

 

[Gale Hawkins]

those old manuals are like gold pending on the tractor i've seen them bring $50 and up for just one thin little manual at antique equipment shows

I paid through the nose for my old JD oem shop manuals but I could not keep it running without them. I find the parts manuals being very helpful because they show the exploded views.

 

[veewee]

Most interesting following this thread. My problem with my JD400 Backhoe is that when I last worked the front bucket the hydraulics emptied the oil out of the filler cap on top of the differential until it drained the rams and I had difficulty getting the bucket high enough to get back to my house. I have fitted a new filter but, the plugs on the filter body don't contain any of the valves as shown on the JD website One just has a rod in the centre and the other has a strong spring with a ball shaped end that doesn't fully cut off the oil from the transmission, as it keeps dribbling into the filter housing after being refitted. I may have created a problem for myself by overfilling the hydraulics, as it was not until I was changing the filter that I noticed a Knurled cap low on the RH side of the manual gearbox and discovered that it was a dipstick and lot of oil flowed out. Any thoughts out there?

 

[Tx Jim]

:welcome: to TBN
Sounds as if you have ""way too much oil"" in trans. Correct method to check the oil level is with engine running and knurled cap with dipstick setting on the threads of extension. I think the 2 things that you need to procure is a model 400 operators & JD tech manual. Hyd's will never operate correctly with the correct valves absent. I also recommend checking/cleaning trans oil sump screen(parts key 15). Access to screen is on RH side close to hyd filter by removing a fitting that has a hose on it. Oil will need to be drained to check screen

 

[veewee]

Thanks for your advice Tx Jim. My setup is different to the one in your diagram, as it is a casting with 3 hoses attached and a cylindrical body parallel to the side of the transmission, but does have a 1 inch plug which I assume contains the screen. As we are in drought with temps 40C here in Oz, and my machine is out in the open, I will continue working on it at a later date and post my results. I don't know whether the overfill caused the front bucket to drain it's fluid, but I'll soon find out.

 

[Tx Jim]

Thanks for your advice Tx Jim. My setup is different to the one in your diagram,

You're very welcome. Sorry you're experiencing a drought. I forgot that sump screen retainer fitting is different on ind vs ag tractor but I think screen is in same location in trans case.