JD4700 hydraulics are jerky/shuddering

dmccarty · Dec 20, 2011

Last summer I was running the tractor and noticed that the FEL was jerking/shuddering when being raised. The tractor needed engine oil/filter, coolant and hydraulic fluid/filter changes so I parked the tractor until I had time to do the work. Work was requiring seven day work weeks over the summer and early fall so the tractor had to wait until now.

The tractor has sat since unused this summer and fall.

I just changed out all of the before mentioned fluids including the hydraulic oil and filter. The shuddering is still happening with the FEL, 3PH, and even the bucket operations. I have a 4n1 and opening or closing the bucket shudders but not as bad as raising the FEL.

When I changed the hydraulic fluid and filter I clean the screen in the housing under the tractor as well. The only thing odd was a bit of clear/gray goo on part of the filter screen. There was not much of it and it did not cover the screen.

I ran the tractor today since it was in the mid 60s but the jerkiness was still present. I have alway used JD fluid.

The shuddering is more obvious with lower RPMs. Running at PTO speed it is not as obvious.

I did not check the fluid to see if it had bubbles today. DUH. Should have looked. The fluid level is fine.

Is there some place that could have a restriction effecting the FEL, bucket, 3PH?

How the heck do you find a leak that allows air into the system?

I sure hope I do not need a new pump.

Thanks,
Dan

J_J · Dec 20, 2011

You should check all of the hyd input hoses and fittings, and re-tighten , or replace if necessary.

Use a hyd gage and check the pressure.

Use a flashlight and check in the tank for bubbles with the tractor running, and notice if the bubbles stop appearing with engine shut off.

dmccarty · Dec 21, 2011

J_J said:
You should check all of the hyd input hoses and fittings, and re-tighten , or replace if necessary.

Use a hyd gage and check the pressure.

Use a flashlight and check in the tank for bubbles with the tractor running, and notice if the bubbles stop appearing with engine shut off.

Hoses and fitting is a great idea. Did not even think of that as a problem. Easy to to do.

Looking for bubbles is going to be iffy due to the location of the fill opening but a couple of mirrors might work.

Where in the heck do you get an affordable gauge? Most of the kits are thousands of dollars and the cheapest was almost $400. Not getting why these kits are that expensive. For the price, JD can make a service call.

Thanks!
Dan

DJNebraska · Dec 21, 2011

dmccarty said:
Where in the heck do you get an affordable gauge? Most of the kits are thousands of dollars and the cheapest was almost $400. Not getting why these kits are that expensive.

Hydraulicstore.com Gauges

Around $12.00

J_J · Dec 21, 2011

You can make up test sets like these for about $30.

Some of the TBN members made these.

Surplus Center - 3000 PSI 2.5" LF LM GAUGE

Also at TSC, Northern hyd, Baileys hyd.

mattridessleds · Dec 21, 2011

hows the fluid level?

dmccarty · Dec 21, 2011

DJ and JJ.

Thanks of the link and photos. I saw gauges at Northern for at most $20. The kits I was seeing online had a few gauges and some connectors. Connectors can be expensive but not that expensive. :laughing:

I was wondering if I could just get the gauge and a section of hose. Just like you two suggested.

Thanks!
Dan

dmccarty · Dec 21, 2011

mattridessleds said:
hows the fluid level?

Yes. Unfortunately.

It rained all day today. Tomorrow only a 30% chance so hopefully I can check fittings and see if I can see into the hydraulic oil tank. It might take a mirror or two but I have a mirror or two.

Then the gauges if needed.

Later,
Dan

dmccarty · Dec 22, 2011

I checked the rear hydraulic connections and they were all fine. I took out the pressure relief value and since it was gunky looking. I cleaned it up but it made no difference.

With two mirrors and a flash light I looked into the hydraulic tank with the engine running and off.

With the engine running I saw the fluid moving. I would not say I saw bubbles. I certainly did not see foam or small bubbles.

Running the engine and moving the FEL, hydraulic top link and 3PH quite a bit, I did not see any obvious bubbles or foam. Turned off the engine and I did not see any either.

Next I disconnected the FEL hydraulics and ran the engine again. The 3Ph still was jerking/shuddering.

The earliest I can get a pressure gauge setup will be this evening or Friday.

If air is NOT getting into the system, what would be the problem? The pump?

Later,
Dan