ARK500 FEL leaks down slowly

[Pete D 83]

My FEL leaks down somewhat slowly when raised.  There is a slight amount of oil on the pistons, but not nearly enough to cause drips.

Could low oil cause this, or air in the system, or am I looking at seal cleaning / replacement?

Does anyone know where/how to check the level, and/or how to bleed?

To clean, will a seal saver for motorcycle forks work?

I presume it uses standard hydraulic oil, such as for aircraft hydraulics or air compressors.

Thank you!

[Pete D 83]

I found this thread  but it does not go into testing or bleeding.  It's also for an ARK550 which I'm guessing is very similar to the ARK500.

 

[wallfish 17,000]

Most used motor oil

The reservoir drain and fill is on the upright. 

To bleed a hydraulic system just use it and cycle through all the cylinders multiple times. The air is released in the reservoir. But you need to keep checking the level as the air is released it's replaced with oil. If it feels "Spoungy" that is air in the system compressing. Keep cycling through to get it all out.

 

The leak down is most likely in the valve. Oil leaking past those seals inside. It just flows through the return lines and into the reservoir. Could also be the cylinder seals.

Raise the bucket, shut off the engine and disconnect that return line at the reservoir and catch any oil in a container. if oils drips it's seals somewhere. If it doesn't it's a leak somewhere

 

Search the files for a manual

[lynnmor 7,307]

1 hour ago, wallfish said:

The leak down is most likely in the valve.

Pay attention to this short sentence, for a cylinder to move an unequal amount of oil needs to move out of one side while oil moves into the opposite side.  Because one side has the rod taking up much of the space even a cylinder with bad seals won’t move much unless there is an additional problem and often that is the valves.

[Pete D 83]

Thank you for the replies.  I considered the seals because if the oil seeped past them, it seemed to make sense that the volume in the pressure side would be reduced, allowing it to drop.

I understand now that this is not necessarily the case, and I will test by disconnecting the return line, as @wallfish suggested. 

This may take me a while to do, as summer chores and maintenance around the home & yard take precedence. 

Happy wife, happy life!

Edited July 6, 2023 by Pete D

[wallfish 17,000]

4 hours ago, Pete D said:

Thank you for the replies.  I considered the seals because if the oil seeped past them, it seemed to make sense that the volume in the pressure side would be reduced, allowing it to drop.

I understand now that this is not necessarily the case, and I will test by disconnecting the return line, as @wallfish suggested. 

This may take me a while to do, as summer chores and maintenance around the home & yard take precedence. 

Happy wife, happy life!

When I had mine it would leak down but not enough to worry about. I had no need for holding stuff up with it overnight so it wasn't really an issue. For winter storage the bucket was rested raised and up against a wall for space reasons. If it's not a bother to you then maybe not bother with it. VERY common for older hydraulic systems to leak down slow. Leaking down fast, that's definitely a problem that should be fixed. 

[gwest_ca-(File Mod) 11,046]

https://www.wheelhorseforum.com/search/?q=ark&quick=1&type=downloads_file

[Pete D 83]

5 hours ago, wallfish said:

When I had mine it would leak down but not enough to worry about. I had no need for holding stuff up with it overnight so it wasn't really an issue. For winter storage the bucket was rested raised and up against a wall for space reasons. If it's not a bother to you then maybe not bother with it. VERY common for older hydraulic systems to leak down slow. Leaking down fast, that's definitely a problem that should be fixed. 

Slow is relative.  It does not slam down, but it drops noticeably when I drive 500 - 1000 feet (6" to a foot).

I guess, in retrospect, that's somewhat fast.  Manageable for the time being, however.

 

@gwest_ca - thank you.  I searched for FEL and got similar results.  The 1980 version shows an exploded view of the valve block, but I won't know if the o-ring sizes will be accurate until I tear into it.

[Pete D 83]

Google found this, which I may go by.  New spool block could be an option if necessary.

 

[Pete D 83]

Update: FEL is Ark 508QM

 

(Found my tractor, formerly for sale here.)