730 CK Hydraulic troubleshooting

[jdamman]

I was previously piggybacking on another post on here, but thought I better start my own thread to reduce confusion.

The problem:
I was using the loader on my 730 (741) to move a mower, it lifted that well, set it down, drove in to rock pile to haul rock and have almost no hydraulic power. The loader won't even lift itself empty, but the cylinders will work back and forth a little. The 3 point, which I had used 2 days ago to lift a backhoe, now will barely lift me standing on one arm (it moves very slow). I don't notice the hydraulic/gear whine I used to when I let out the clutch in neutral. PTO seems to work normal, haven't had a load on it since hydraulic issue, but the PTO clutch handle feels normal.

A bit of history:
This tractor has typically been slow to "pump up" the hydraulics. You'd start the tractor, then wait a bit (20 seconds? depends on how recently it'd been run, ambient temperature, mood) before I'd have loader or 3 point power. We've been using this tractor as a weekend warrior for the past 5-6 years, but previously it'd set for probably 10 years with a head gasket/stuck engine problem. When my dad and I revived it, we had similar challenges with the hydraulics. Dad went through the control valve with little improvement, then it just kinda started working progressively better. One set of remotes seemed to work better than the other. I used the good set for the loader, which would lift the front of the tractor, or lift a bucket load decent, and the second set I used on the back blade rotate. One direction it always worked well, the other direction it sometimes worked well, sometimes it got really slow, but it was adequate for what I needed.

Some of these symptoms may not be at all related, but, better too much information than too little, right? I do have an I&T manual (of minimal help) and I've found the online parts book resources.

In attempt to troubleshoot / diagnose the issue, I have:

-Checked and topped off the hydraulic fluid (a little milky, nothing too bad. No noticeable air bubbles. Did full fluid and filter change 18 months ago)

-Changed the spin on filter over the axle (I was a little surprised it didn't have more fluid in it, tractor had been run within an hour)

-Checked hydraulic pressure at the remote quick connects. About all I got was a gauge flicker, I can feel the hose move a little, but nothing like you'd expect.

-Pulled the pump. I noticed the pump turned decent one direction, the other was very difficult by hand and I didn't want to put a tool on the gear.

-Blown air in the pump pickup port in the tractor in attempt to clear screen obstruction, if any. (through #3)


In the process of writing this, I had another thought. Is the gear on the end of the pump shaft (#4) supposed to be beveled or bull nosed to help with installation alignment? Because this one is. The roll pin is intact, but the gear seems a little loose on the shaft. There was a little black grime on the dipstick magnet, for what it's worth.

Something I haven't done yet, and I think is my next step, is to take the pressure line from the pump and direct it into a bucket to check flow.
-If there is good flow, where do I go next?
-If there isn't flow, can I run the tractor without the pump in the hole to make sure the pump drive shaft is spinning? Are there any other steps I should take before dropping the tail housing off the tractor?

I have no problem doing the work, but I want to do my best to diagnose it before pulling the tail or something else labor intensive to no avail. I'm a little hesitant because I heard lots of fluid gurgling around when I blew in there.

Sorry for the lengthy post and list of questions, and thank you for any and all help / insight y'all can provide.

Joel

 

[jdamman]

Here's a hopefully better diagram for discussion purposes. I think the item numbers are a little more clear.

Thank you again!

 

[Adirondack case guy]

In an ideal world you should put a flow meter onto the pump circuit and check flow at rated pressure, but we all don't have these tools. My first thought would be to check the condition or existance of the Quad ring, item#3, and make sure the pump is drawing oil from the pickup strainer. Secondly, I'm not sure why the pump doesn't turn well in one direction???. 3rd, I would remove the main relief and inspect it for lodged debries, or broken parts. 4th, an after thought, and unlikely, would be a broken or stripped pump drive coupling.
Loren

 

[jdamman]

Thank you - I've found several reliefs in the parts diagram: can you help direct me to the main relief? I can see what I believe are ones under the auxiliary/remote valve body, but I don't think I can get to those without pulling the valve body. As for the quad ring, item #3, it is in place, didn't look terrible, but I wondered a bit about that myself. Are there any other places the pickup can leak air? Seems like it'd have to be a massive leak to suddenly cause such a failure in power.

 

[Brokengun]

From your description it sounds like your getting NO flow at all.

Like Loren said it would be nice if all of us had flow testing equipment but we don’t.

These are just my thoughts on your problem…I have also experienced similar problems on one of my 930’s. My pump was bad, one of the bearing babbits failed, I didn’t discover the problem until I took the pump apart.

My first impression from your comments is that your pump maybe bad; However Pumps are expensive and shouldn’t be replaced unless they are bad and ALL other problems repaired.

You mentioned something about running a hose to a bucket. Are you talking about plugging a hose into an outlet and running it to a bucket?

That will tell you if you are getting a flow of oil but it does have some risk. You will need to secure the hose.

If you do have flow then the next thing I would check is the relief valve at the hyd spool part #12

You said you took the pump off, was there a seal for the intake on the pump?

Unless the screen on part#36 is plugged or the seal for the pump is missing/bad, I can’t recall any other part that could cause a flow problem other than a bad pump.

P.S. if you pull the rear housing off the tractor you will need an engine crane. The screened intake is cast and it sticks out from the housing and it’s possible to drop the rear housing and break the intake screen.

It’s hard to wrench a problem from behind a computer screen so realize my suggestions are just that, suggestions.

Good Luck!

 

[jdamman]

(quoted from post at 12:54:02 05/15/13)
If you do have flow then the next thing I would check is the relief valve at the hyd spool part #12

Is that #4 in this diagram (below)? Looks like I'd have to pull at least the seat and valve body to get at that, right?

And thank you for the suggestions, I understand wrenching through a screen can be difficult, hence all of the details. I plan to go home tonight with these new ideas and direction to further investigate. I should have looked at the pump gear closer last night but it was getting late and I was getting tired.

 

[Adirondack case guy]

The main relief valve is #4 and you have to remove the entire remote control valve to acess it. Good luck with the two top 1/2" capscrews, that hold it on. The other spring loaded valves are flow checks for each remote which can go bad and allow an implement such as a loader leak down.
Also, if you do pull the back housing, you don't have to completely drop the whole 3pt assembly off the tractor. Just remove the drawbar and the 3/4" capscrews from the drawbar/3pt support assy and let it swing down, pivoting on the wishbone springs. then cut heads off two 6" long 5/8" bolts to use as guide bolts, and then use a chain hoist or cherry picker to remove the housing. This should eliminate the possibility of breaking the cast suction screen.
ps I like to slide a 3' peice of pipe over the PTO shaft to break the gasket loose and stablize the housing during removal and installation.
Loren

 

[jdamman]

NEW INFORMATION

So, I established that I have reasonable flow, but minimal pressure. I hooked up a hose to one remote, put it in a bucket and in fairly short order, I had the bucket half full. I believe the spec is somewhere around 12GPM, which I'm probably in the neighborhood of (at low pressure).

So, I proceded to remove the auxiliary / remote valve block to inspect the main relief valve. The first thing I noticed was a gelatinous goop in there (where did that come from? Moisture?? Have basically been using farm store universal trans-draulic fluid.) - see picture. I removed the relief valve and the strainer was laying crossways in the bottom (as on the tractor, top as I was disassembling) of the port. The rim seemed to still be under the spring, but it seems to have somehow separated.

I don't know if the strainer could have somehow jammed the relief valve open? It doesn't make much sense to me. The piston seemed to seat ok when I played with the pieces and I had to push on the spring to start the threads to reassemble. So, any recommendations on where to go from here? I figure putting a new strainer in is in order, and probably cleaning out the obvious goop. Should I take the valve further apart, or slap it back together and see if that improved things?

Thanks again for all the help!

(First picture is upside-down. Darn technology :roll: )

 

[jdamman]

Holy cow! I just looked up what Messick's wants for that little strainer: $71!!!
I haven't checked a dealership (nothing open at the moment) but I'm open to sourcing suggestions!

By the why, what is that strainer straining? It seems to me that it's on the back side of the piston, where fluid wouldn't be?

 

[Brokengun]

It looks like your on the right course. I had to grab my 30 series book to get an idea of what you found.

From what you described I think you may be correct that the screen somehow held the relief open, causing your problem.

Unless something is broken or damaged I think you can “CLEAN” everything and put it back including the screen.

The one thing I would question is the relief valve spring IF and I mean if I’m looking at the right info your spring should measure a free length of 1-11/16 inches with a 14lb test at 29/32 inches. [From the picture I think you may be “OK”]

Has far as the goop goes I think it is a moisture problem and I hate to say this but it could be your oil.

This is just my suggestion but go ahead and clean everything up replace any parts that are bad or damaged and try it and see if it fixes your problem if it does then you might want to consider changing oil

 

[jdamman]

SUCCESS!

I cleaned the main relief valve, and also cleaned the aux pilot valve (#12 below) and between the two got things working again. Out of curiosity, #5 in this diagram is a small pipe plug. There's one top and bottom, and maybe a couple on the back. Are these construction holes, or can you use them as diagnostic ports?

So, now that I have things working again, a fluid change is on the maintenance list. I changed the fluid and filter probably 18 months and maybe 30 hours? ago. It stayed clear through the first winter, but I kind of lost track after that. Is there a known issue with the fluid I'm using? Travellers Universal Trans-draulic fluid (I know better than to ask what the best oil is...)

Anyway, many thanks to all; a repair at the cost of some time, a filter I had on hand and a few gallons of fluid! (pretty exciting when I was concerned about an $800 pump initially)

 

[Brokengun]

Congratulations!!!!

You have a very nice looking tractor, its well worth taking the time to keep it going.

To try and answer your question on the #5 plug. I think the top plug is a test port for pressure testing the system.

Has far as oil goes I think the oil you used foamed up due to water contamination. [That’s the goop you found]

Hytran is the best oil to use because it also can disperse up to 1% water by volume and has anticorrosion problem but even Hytran can’t handle a large amount of water.

There is a chance some of your water problems could be the rubber boot over the gear shift lever. A new gear shift boot is around $12-$15.

It’s not that hard to do and might be worth checking out.

Again Congratulations I always like to hear success stories. Thank God you didn’t have to buy a new pump!