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856 steering still not working right after MCV rebuild


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38 minutes ago, Diesel Doctor said:

My thought was the PS cooler line had broke, operator did not see it and pumped all the oil on the ground.

This roasted the MCV pump as it was running dry.

But, the MCV pump has been replaced and helped steering, when it works.

Will the PS quit when you go to idle without pushing the clutch?

Just slide it out of gear and throw up the throttle to idle.

Does the PS quit after a few seconds.

Is pushing the clutch a normal practice which actually has no effect on the problem?

Is the bill available from the mechanic?

You were busy with health matters.

What is said the problem was and how was it fixed?

How much Hy-Tran were you billed for?

I cannot say the head gasket change could effect the hydraulics. Unless I am missing something.

Thinking outside the box?

Thanks for the thought. At idle, PS works fine no matter how long it sits. No problems except when the clutch is activated. I’ll have to see if I can find the bill. 

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I haven't had one lose steering with the clutch depressed, but I had a 966 many years ago that lost power brakes because of a bad brake check valve. It's worth checking. How did the steering check and spring in the side of the housing look? 

IMG_20240510_1041245.jpg

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Just spit-balling here, but is there any way that things could have gotten connected incorrectly? If hard lines were replaced by hoses at some time in the past, maybe some lines are crossed. The power steering pilot valve is somehow getting its supply from the dump valve, maybe? 

The loss of function seems to coincide with the dump valve bleeding off pressure. 

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That is totally ignoring the priority function to the steering of the flow divider

Thought the OP said he disconnected the dump valve  , with no change in the symptoms

Dump valve pressure is about 1700 psi lower than steering pressure
so steering would not function at all with TA pressure

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1 hour ago, HydroTek said:

Thought the OP said he disconnected the dump valve  , with no change in the symptoms

I went back to read again, and yes, he did say that. OK, that's goofy. Nonsensical even. 

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Well then all I can recommend is to call a young priest and an old priest, because it's time for an exorcism.

The only other thing I could think of would be the IPTO drive somehow stripped itself out of the pressure plate and welded itself to the transmission input shaft, but that doesn't explain how the remotes, 3pt and pto continue to work.

Just to be sure here, you stopped the tractor, held down the clutch, and actually lifted and lowered an implement using the hydraulic remotes? You stopped the tractor, held down the clutch pedal and operated a PTO implement?

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if the PTO turns at all -- then the pump drive shaft is turning

Hold the remote lever on demand and listen for the relief sound  , will work for testing if the pump is running -- if the 3pt can lift at all , then the pump is running

OP -- did you drop the left tire in a ditch and see if that made a difference yet ?

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3 hours ago, Matt Kirsch said:

The only other thing I could think of would be the IPTO drive somehow stripped itself out of the pressure plate and welded itself to the transmission input shaft, but that doesn't explain how the remotes, 3pt and pto continue to work.

I was going to say that, but I didn't want to sound Whacko! haha!  But the whole scenario is whacko.....

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3 hours ago, Matt Kirsch said:

Well then all I can recommend is to call a young priest and an old priest, because it's time for an exorcism.

The only other thing I could think of would be the IPTO drive somehow stripped itself out of the pressure plate and welded itself to the transmission input shaft, but that doesn't explain how the remotes, 3pt and pto continue to work.

Just to be sure here, you stopped the tractor, held down the clutch, and actually lifted and lowered an implement using the hydraulic remotes? You stopped the tractor, held down the clutch pedal and operated a PTO implement?

This is kinda what I was asking in my post, if he still had remotes after releasing the clutch. This is crazy problem, a first!

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1 hour ago, HydroTek said:

Tilt the tractor to the left and report if the problem goes away

where is that dead horse meme when I need it ?

lol was pouring rain today and I had to fix one of the trucks instead. If this works, what is the direction this points? That the passage through the TA that supplies the pump is cracked? I know you had mentioned that before. 
 

But to all the previous posts, yes. PTO, 3pt, rear remote all work regardless of clutch being pressed. Whether the clutch is in out, being let out, whatever, I have no issues with the main hydraulics whatsoever. I’m baffled. The issues with steering, brakes, and TA existed both before and after the MCV rebuild. 
 

@Matt Kirsch either a priest, or perhaps taking out behind the barn and putting it out of its misery! Haha

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Go back in time when this 856 worked as it should.

This problem was first noticed after coming back from the neighbors.

What had been done to it before this started. 

You still have not explained the big oil leak by the MCV valve? What was leaking and what was fixed?????????????????????????

You also had the head gasket replaced, before this problem started.

Was anything else fixed????????????????????????????????

The tractor came back from the shop and went to the neighbors.

The problem was found after coming back from the neighbor.

Talk to the neighbor, explain the problem and ask him if he experienced this?

You are not accusing him of anything, you just need to know what he experienced when running the tractor.

Did the neighbor do any work to it?????????????????????????????????

You said this problem was happening so you overhauled the MCV valve which did not fix but new pump helped steering.

Something happened in the shop or at the neighbors that caused this.

You also said you have had a lot of issues with this tractor, what were those?????????????????????????????

Just looking for clues!

PS: If not fixed by mid-June, this tractor will be the subject of discussion at RPRU2024.

 

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Ok, finally did the tilt test. Left side down, I lose steering even without the clutch pushed. Right side down, I could hear the pump whining and steering was intermittently stiffer, though I didn’t lose it entirely. 
 

@Diesel Doctorthanks for the questions. I’ll do a full write up about it later today. 

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8 hours ago, Diesel Doctor said:

You still have not explained the big oil leak by the MCV valve? What was leaking and what was fixed?????????????????????????

I wish I could find the receipt for it, but no luck yet. I told you wrong earlier, it was leaking between the trans and rear axle case. Not up by the mcv. 

 

8 hours ago, Diesel Doctor said:

Was anything else fixed????????????????????????????????

Nope, that hydraulic leak and the head gasket. 
 

8 hours ago, Diesel Doctor said:

Did the neighbor do any work to it?????????????????????????????????

 

Haha no. He had for maybe 5 hours running the baler, claims he didn’t notice any issues with it. 

 

8 hours ago, Diesel Doctor said:

You said this problem was happening so you overhauled the MCV valve which did not fix but new pump helped steering.

Something happened in the shop or at the neighbors that caused this.

You also said you have had a lot of issues with this tractor, what were those?????????????????????????????

Just looking for clues!

PS: If not fixed by mid-June, this tractor will be the subject of discussion at RPRU2024.

 

I really appreciate all the attention this thread has received, and for all the knowledgeable responses so far! Hoping we can get this thing functional again. 
 

Since 2016 when I bought it, I’ve had a litany of problems with it. 

-2 T/A rebuild, 2016 and 2019-ish (once right after I bought it under warranty because it was supposedly rebuilt before purchase) 

- 1 clutch, 2020

-2 pto shafts, 2019 and 2022 

-2 pto clutches, 2019 and 2021

-head gasket, 2023

-hydraulic leak mentioned before, 2023

-2 left spindles 2019 and 2024

-1 right spindle, 2024

-both front axle knees, 2024

-MCV, 2024

Nothing ever massive, but downtime pretty much every year, almost always during hay season when I can’t afford to be down a tractor. 

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1 hour ago, cam.man67 said:

Ok, finally did the tilt test. Left side down, I lose steering even without the clutch pushed. Right side down, I could hear the pump whining and steering was intermittently stiffer, though I didn’t lose it entirely. 
 

@Diesel Doctorthanks for the questions. I’ll do a full write up about it later today. 

Definitely have suction leak on right side. Now begins the guesses where.

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Well,
the tilt test did not pan out the way I would have expected

Kinda indicates that the suction tube in the rear housing or the filter cover -- one or the other is not sealing

Do you have the "tin" cup that goes in the filter housing -- that the filter sits against ?

...still not connecting pushing the clutch with oil loss tho

a suction leak at the filter should affect both pumps
the mcv pump sucks from the bottom of the housing
the rear pump sucks thru the jumper tube at the top of the filter housing

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7 hours ago, HydroTek said:

Well,
the tilt test did not pan out the way I would have expected

Kinda indicates that the suction tube in the rear housing or the filter cover -- one or the other is not sealing

Do you have the "tin" cup that goes in the filter housing -- that the filter sits against ?

...still not connecting pushing the clutch with oil loss tho

a suction leak at the filter should affect both pumps
the mcv pump sucks from the bottom of the housing
the rear pump sucks thru the jumper tube at the top of the filter housing

Yep, the tin cup is intact. 

7 hours ago, snoshoe said:

My guess is the oring between housings. That's when the problem started. Isn't it?

That makes sense. Don’t suppose there’s any way to get to that without splitting the tractor.  

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Oring between the housing would be my logical guess also but doesn't explain what releasing the clutch does. Been working on these RED tractors for over 50 years and have only seen one with a cracked speed transmission housing and kept losing prime and that was a warranty issue with a 766. Can't hardly believe to have a suction leak in the rear housing, never looses prime to the hitch pump, so that leaves from the split forward beginning with the oring.

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Have to split for the oring😀. Have you over filled the transmission with about 6 gallon oil??  Alot  of guys say five gallon is enough to check for air leaks but I have seen up to 8 gallon needed with the gears spinning. Worth a try??

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