2150 Slow Hydraulic Pressure Realease

Hi Everyone! I'm new here, and this is my first post. If this topic ought to be moved to a different subform, I hope a moderator can take care of that. I'm very familiar with car forums, but tractor forums are a new for me. Anyway, down to business.

I have a ~1987 2150 with a 146 loader on it. The past few days I have been working on getting one of the rear wheels repaired and re-ballasted. The tractor was parked outside with a tarp over the central controls, seating area, and instruments cluster. After completing the wheel repair, I started the tractor and noticed a whine from the hydraulics, it seemed. It went away after a little bit, but I then noticed that when I shut down the tractor and attempted to lower the loader by releasing the pressure in the system, the bucket would not even lower or it would lower extremely slowly. I attempted this multiple times after moving the bucket through its entire range of motion several times. I had driven the tractor, let it idle for near 15-20 minutes, and still the same situation. I verified proper amount of hydraulic oil, and the oil that I removed when pulling lines to check for blockage appeared fine with no particulate or severe discoloration. I can hear a bit of a whine from near the side of the transmission, like fluid squeezing through a crevice, when I lower the loader with the tractor off (if it does lower). Recently, I put a new hydraulic fluid filter in, but I hadn't done the screen (just discovered that one this evening ). Everything appeared to be fine after that service a few weeks ago. I also have fitted a few new hydraulic hoses and such, but those didn't cause any issues for a while, so now seems like an odd time.
I attempted to poke around in the metering/control module that the loader control lever manipulates. Removing the fittings for the main lift hydraulic cylinders didn't reveal any odd details or contamination to me. I don't know where to go from here. Short of digging deep into the trans and hydraulic system, something I'm not ready to do, I don't know what could be causing this. Do any of you hydraulic experts know what could be going on here?

Thanks,
Tim

Welcome to YT
I highly recommend to check/clean hyd sump screen. What type valve controls frt end loader? Are any quick disconnects involved in loader hyd circuits? If so with all hyd pressure relieved disconnect/reconnect all quick disconnects associated with FEL to be sure the balls/poppets when connected are allowing hyd oil to flow through correctly.

(quoted from post at 08:09:52 05/20/20)
Welcome to YT
I highly recommend to check/clean hyd sump screen. What type valve controls frt end loader? Are any quick disconnects involved in loader hyd circuits? If so with all hyd pressure relieved disconnect/reconnect all quick disconnects associated with FEL to be sure the balls/poppets when connected are allowing hyd oil to flow through correctly.

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Hi Tx Jim! Thanks for the welcome.

I will definitely be ordering that hyd sump screen asap. It would seem odd that it would cause excess back pressure on the loader hydraulic release, but it still needs done. I don't know what type of valve options there are. It appeared to have a plunger that moves between a neutral position to allow fluid to flow directionally. I can grab a picture of the control valve module if that would be helpful? I did remove the quick disconnects and relived the pressure by pressing the steel balls up against a surface, and the fluid came out of the lines freely. I also removed the female end on the valve controls, and no apparent obstruction was found there. The balls all appeared to seat properly, and fluid seemed to flow through it just fine with the quick disconnects connected to one another, but disconnected from the valve controls. Is it likely an issue with the female ends of the quick disconnect that is hard to track? If any pictures or videos would be helpful (assuming the forum supports the attachments?), I can grab those, no problem.

Sorry I didn't intend to imply sump screen caused back pressure but a clean screen helps for better/faster hyd operation.I suggest to attempt to clean screen before replacing screen(R53169 $24.03). The important thing about QD's is to be sure they're seated correctly so oil can freely flow around the balls when connected.

Possibly an inner liner of a hose has failed due to age or from being kinked. Or as previously stated, the hydraulic quick connectors must be fully seated.

(quoted from post at 09:58:21 05/20/20)
Sorry I didn't intend to imply sump screen caused back pressure but a clean screen helps for better/faster hyd operation.I suggest to attempt to clean screen before replacing screen(R53169 $24.03). The important thing about QD's is to be sure they're seated correctly so oil can freely flow around the balls when connected.

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Not knowing the history on this unit (The tractor is my grandfather's, and I'm just doing the service.), I just opted to replace the screen. The part should be picked up today.

As for the quick disconnects. I am rather certain they are all seated just fine. I never touched these items before the unit started acting up, so the only thing I could figure is an obstruction in one or the other. However, my visual inspection of them didn't reveal any obvious clogging in the unit. Is there a way to clean or better inspect them that I am not aware of?

(quoted from post at 10:39:16 05/20/20)
Possibly an inner liner of a hose has failed due to age or from being kinked. Or as previously stated, the hydraulic quick connectors must be fully seated.

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Good thought! Most of the hydraulic lines on that circuit are new, but not all of them. How does one check for internal failure of a hose? Kinking may be a problem, but the evidence of such seems to be lacking.

I have a picture of the control valves when I was taking the quick disconnects apart and out. I know this isn't informative with getting an idea of the problem, but this is the unit I am working with. Anything in here I should check?

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Although I have no previous experience with one of the valves being at fault held in place with cap with hex shaped recess it wouldn't hurt to check them or operate loader with the valves removed.

So to provide an update on this topic, I changed the screen out for the transmission. The old one had some minor junk in one side, but nothing concerning. That didn't make any difference in operation.

I took the spool valve apart and inspected the valve body, spools, valves, and so on. I found a chunk of dirt in one of the spools, but no other pockets of junk. Additionally, some of the valves had o rings that were worn down to nothing, but I'm not sure if that was just general wear or sand blasting from dirt in the fluid. Those were replaced, too. After soaking the valve in a heated solvent bath, nothing changed with the operation. Next, I swapped in 4 new quick disconnect valves. Still, nothing changed.

However, I discovered something new while working with it tonight. If the bucket tilt is maxed out to its fully retracted or fully extended position, the excess pressure developed in that circuit will slow the operation of the lift. For some reason, it seems the pressure bleeds over to other circuit inhibiting the speed of motion. So if I fully retract the tilt right before turning it off, I can expect the lift to have tons of back pressure in it causing it to fall slowly. Additionally, when the tractor is running, if the tilt is maxed in one direction or another, the powered lowering of the lift cylinders will go slower compared to if the tilt is in some space between it's absolute maximums and unloaded.

I'm not sure if this is normal operation, but I find it odd that one circuits pressure has the ability to affect and hinder the operation of the other. That doesn't seem right to me. So despite my cleaning and inspection of the two spool valve, I still think the valve is at fault in some way. Unfortunately, changing that out for the heck of it can only happen to the tune of $2300, so it doesn't sound likely. Anyone have ideas as to what is causing the odd interaction between circuits in the valve body?

You can get a new 2 spool control valve for a lot less than $2300. Just be sure to install a closed center plug in the new valve.

Really? How would I go about getting something that would mount with the right bolt holes and hook up in the exact same way? Where should I look? The only thing I know about is what the Deere dealer offers.

Due to the fact that the valve in your photo which i think is AW20889 NLA I think you'll find it difficult to locate exact valve body. Drilling a few holes in mounting bracket to save a couple $1000 would be a ""no brainier"" for me. I think getting a 2 spool valve with correct thread size or with adapters can be accomplished. After all JD has been outsourcing hyd control valve since the beginning.

That's a good point. I would be willing to do that, but I haven't seen anything in my searches that would even fit the required need with the cable hook up locations and fluid inlet and outlet ports with reference to the quick disconnect ports. Should I pursue the options that Eaton has since they made this unit? Also, what about the option of getting this valve rebuilt? Is that something you would recommend?

Only thing that can be performed in a rebuild is replacement of seals. If tolerance between spool & housing isn't correct the complete valve housing including spools must be replaced.

So replacement of the valve is the best option at this point. Just to be sure, this operation is not normal, correct? I don't ever recall the pressure developed in the tilt affecting the operation of the lift. But if that is normal, I am fine with it.

By chance does your 146 loader have the option of regeneration valve(item 9) which if faulty could be affecting bucket cylinders operation time?

Unfortunately not. My setup is shown in the diagram below. Have you ever encountered this type of loader behavior before? Also, what would cause a spool valve to "go bad", if it is indeed bad?

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Circling back to the spool valve, the only bit that I couldn't get apart when disassembling were parts 1-4 in the diagram. They were super stuck, and I didn't want to damage the flat head on the threaded plug. Is it worth pursuing these little poppets further, or is it unlikely to be the problem? New caps, if I damage the heads, are over $40. Seems a little high for some flat head fasteners.