Iseki 2140 hydraulic problem 3pt lionkage

[636rjb]

hi everybody, my first post.

Symptoms of the problem are as follows:

Three-point linkage became sluggish and only worked with high revs

Drained the oil, checked the suction filter (had been punctured with a screwdriver or similar)refilled oil

Three-point linkage now failed altogether

The pressure release valve appeared normal and I have tried it in various positions

Measured pressure on trailer outlet- 1800 psi, accompanied by a change in engine noise

Some air bubbles seen in the oil

the present situation is that the three-point linkage will rise when the engine is cold, but has no strength, gets rapidly worse as the engine heats up

The advice that I have been given suggests hydraulic pump problem despite the reading on the trailer pipe. I have some doubts about this but would appreciate any advice.

 

[J_J]

If the pressure that you indicated is your relief pressure, then the pump appears to be working fine.

Do the test, both cold and hot.

As the hyd fluid gets warm, the leakage will go up.

Your 3pt piston seals could be worn.

The 3pt valve could be leaking.

You can do a pressure test on the pump by using a needle valve and relief valve. Do not fully close the needle valve, or you might deadhead the pump. Your pump could very well build up pressure beyond the relief setting for our tractor. The manufacturers limits the pressure for different reasons.

 

[636rjb]

Thank you for your reply. The piston seals were checked, and indeed one was damaged -- we thought this was the cause of the problem -- but no change after installing new ones! The pressure release valve has been tried in various positions.

I am beginning to wonder about the system behind the raise and lower lever. One source of advice (well-informed I think) suggested this is a rather complicated area to dismantle. The other thing I wonder about is an air lock. Loosening the pipes under pressure sounds are rather messy and dangerous procedure --?

All comments are welcomed.

 

[J_J]

Hyd fluid moving through a hyd system will usually move any air to the tank, however, if you have a suction leak, constantly making bubbles, you will have air in the system. Cavitating fluid from a relief valve will generate bubbles.

The purpose of the descent valve is to set the rate of drop and to lock the 3pt for transport, so if you raise the 3pt and lock it down, theoretically, you lock the 3pt, but if there is a leak in the 3pt seals, the 3pt will drop, because the fluid is leaking into the rear end.

People rebuild pistons in cyl all the time, and some still leak.

If you are still using the same valve, the spool may be worn. Perhaps the 3pt lever is not going back to neutral.

 

[636rjb]

Thanks for the advice. you mention the "spool"- what exactly is that? There is an O-ring on the release valve which I have replaced.I will try your suggestion of seeing it sags on tightening the drop valve, although the problem is getting it up first is the problem!

Where are the likely sites where air could get in?

Best regards

 

[J_J]

Suction hose.

Relief valve.

Pump seals.

 

[636rjb]

Thanks for that JJ, The pump seemed difficult to dismantle, and no seals were seen other than the gasket between pump and block. The relief valve ring seal looked OK.

Air is getting in somewhere making the oil on the dipstick foamy and white.
I tried tightening the drop valve and checking for drop-none seen.

The mystery continues!
I

 

[J_J]

Re-tighten all suction clamps.

Some people apply grease around the suction clamps and suction tube.

 

[Leejohn]

You said ( oil on the dipstick foamy and white ). Is there water in the oil? The trans gears will mix it up turning it white and it might also make it foamy.

 

[636rjb]

Thank you for the suggestion, but we changed the oil for new, and the tractor is not exposed to rain, so no obvious source of water input. Air being sucked in seems the best guess, one suggestion was that it may be due to a crack in t he pump.

We may have to bite the bullet and buy a new pump to find if that really is the problem....