3 pt load dropping

rtd · May 3, 2012

A moderate wt load (approx 300# yard rake) after being raised to max ht on my 155D will drop to the ground in about a minute. Ten, or even five minutes might be tolerable but the current rate is not.

I suspect that the seals in the internal cylinder are leaking. Is this a difficult job? Are seals available; I can check with Hoye. Is it better to replace the cylinder?

Thanks

winston1 · May 3, 2012

Sending you a pm.

Soundguy · May 3, 2012

i don't have that model, but speaking in general, if a tractor drops a load on the 3pt hyds after shutting the pump down, it's a leak on the cyl siside.. usually a safety / relief valve or the piston rings.. latter most often.

soundguy

clemsonfor · May 3, 2012

You can either have a leaky valve or cyl oring. There is a thread here by JD...... where he did it with pics in his like 186 or something. Its an easy job. But you need to make sure its the cyl. No you dont buy the whole cyl, its an assembly for the top of the trassmission, sure you can buy the cyl but the oring is the problem usually a cut in it. You need to close your know under your seat and see if it still falls. If so its the leaky piston oring if not its the valve under the pressure line that the 3pt lever controls bypassing.

The oring ( for the cyl)costs less than the shipping to get it to you from HOye.

Ginormous · May 3, 2012

Is it dropping while running or after you stop the engine? Did you check to make sure it's not simply the hydraulic lift control handle sliding down? That's a pretty common problem...

clemsonfor · May 3, 2012

Sounds like as the engine is running. Which i consider to be the valve, but not sure?

Domush · May 3, 2012

It sounds like the cylinder o-ring. It is a thick o-ring ~3" in diameter and only costs about $15. You'll be deceived when you first remove it, as it will look brand new. My o-ring looked brand new, but the 3ph couldn't lift anything, when replaced it would lift the front end of the tractor off the ground.

The only other possible issue not mentioned by others is the self leveling mechanism (if your tractor has one) may be mis-adjusted and is slowly lowering the 3pt when it is level already. But it's probably the o-ring.

rtd · May 4, 2012

Thanks for your replies. Here's an update:

I performed an informal test without the previously mentioned load but no other change:

1) with engine running - stood on the lift arms with the arms in the maximum lift position - with my 160 lbs it dropped about 1" in a little under a minute.

2) with engine running - closed the 'drop-rate' valve and stood on the lift arms as before - I could see no obvious drop after about a minute.

I need to repeat the closed valve test with the heavier load and a stopwatch.

Domush · May 4, 2012

Why bother running more tests? It's not working correctly. With a new o ring mine doesn't drop more than an inch per week with a 7'grader blade on it.

The entire point of the three point system is accuracy. Imagine leveling a driveway with multiple inches of difference between one side and the other due to your implement dropping on you as you drag it.

Or mowing a field where you start at a cutter bar height of two feet high and end at it sitting on the ground chopping rocks.

it's your tractor and time. You can go to a lab to get your drop rate certified if so inclined.

clemsonfor · May 4, 2012

Domush said:
Why bother running more tests? It's not working correctly. With a new o ring mine doesn't drop more than an inch per week with a 7'grader blade on it.

The entire point of the three point system is accuracy. Imagine leveling a driveway with multiple inches of difference between one side and the other due to your implement dropping on you as you drag it.

Or mowing a field where you start at a cutter bar height of two feet high and end at it sitting on the ground chopping rocks.

it's your tractor and time. You can go to a lab to get your drop rate certified if so inclined.

Because with the results he said its NOT the O ring on the piston. If you close the valve under the seat this takes out the valve on the 3pt and only leaves the piston O ring. IF like he says he closes the valve off and stands on it and it dosent drop any than that means the 3pt valve that controls the lift height is the problem. its either internally bypassing or has trash stuck in it.