John Deere 1640 Strange Hydraulic Problem

[Tx Jim]

With hyd oil warm, engine operating 3 pt raised or 3pt control lever to the rear look into open hyd filler hole for moving oil. Moving oil indicates faulty 3 pt control valve seals. Internal hyd leaks causes hyd to heat lowering it's viscosity & lowers amount of oil available for frt pump therefore causes frt pump cavitation.

 

[historyan1975]

With hyd oil warm, engine operating 3 pt raised or 3pt control lever to the rear look into open hyd filler hole for moving oil. Moving oil indicates faulty 3 pt control valve seals. Internal hyd leaks causes hyd to heat lowering it's viscosity & lowers amount of oil available for frt pump therefore causes frt pump cavitation.

Thanks,

As I see, we have a multiple type of problems. What should be do?! Where do I find this control valve - to replace seals?
I checked on a few diagrams, but I could not to identify it...
Probably that the oil pump is not guilty for the problems, should we forget for now the pump problems__?!
Before - we replace the control valve seals?!

Thanks, Benedek J.

 

[Zebrafive]

Per TxJim: If you see oil spraying, looking in fill cap of the rockshaft housing, you have leaking rockshaft (3pt) valve seals. You have to remove the rockshaft housing to access the rockshaft cylinder/valve assembly.
I would check/repair this before changing the front pump.

 

[Tx Jim]

Ditto what Zebrafive stated. Repair internal hyd leak then proceed with more hyd diagnostics. Hyd internal leaks are contributing to poor frt hyd pump performance

 

[historyan1975]

Per TxJim: If you see oil spraying, looking in fill cap of the rockshaft housing, you have leaking rockshaft (3pt) valve seals. You have to remove the rockshaft housing to access the rockshaft cylinder/valve assembly.
I would check/repair this before changing the front pump. View attachment 693866View attachment 693867

 

[historyan1975]

Ditto what Zebrafive stated. Repair internal hyd leak then proceed with more hyd diagnostics. Hyd internal leaks are contributing to poor frt hyd pump performance

O.K., I understand... Maybe -the big piston sealing are used (AR33105)? Or, we have to replace all seals on the piston and at valves.........?! DOES exist any repair kit for the valves? If not, what should be replaced from those little pieces from the valve diagramm? Only the O-rings_?

 

[Tx Jim]

Rockshaft control valve seals/gasket kit part # is AL57974 & piston seals are part # AL33105

 

[Jimbo1640]

If memory severs me, this is what our Hydraulic Relief Valve looked like after we pulled it. Notice the O ring on the left was shot and in pieces. Cheap fix with an assorted O ring kit, although I've found it is better in the long run to order the real thing from John Deere--they last longer and aren't very expensive. It may also be called the Filter Bypass Valve-- can't remember, did a lot of valves on this tractor.

 

[Jimbo1640]

You should check out this guy. This video is about the Filter Bypass Valve on a 1640, but the principle remains the same for all these valves that are accessible from outside the tractor without taking the top off. In other words, do the cheap stuff first. It was worth watching just to get that hint about making sure the split in the split pin faces away from anything that is going to bang against it.
Btw--he is also has extensive videos about a 2030 he has been working on. Well worth the time.

 

[Jimbo1640]

Here is another that you may or may not find helpful: the Flow Control Valve, or Pressure Control Valve, located under the right footrest, which you have to remove for easy access and also drain your hydraulic oil. This was an sob to get that nib off, and I had to eventually remove the whole thing. Notice once I got the nib off and the valve out, the O ring that was in pieces at lower middle 2nd pic. Also, where the pipe cleaner was going in to clean the port--that has an O ring that you place there after you get the whole thing cleaned up and are going to reattach to the tractor. Make sure you put a dab of grease on that spot to hold the O ring in place. Finally, the nib on the tractor which is helpful to remove and clean up, takes two new O rings to make a nice tight fit when you put the unit back on. Your configuration may not be the same but the principle is. My guess is that Tx Jim is right, you need to pull the Rockshaft, but doing these valves does not go astray.