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No hydraulics after fluid change


gwoswald
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Hello all,

Just changed the hydraulic fluid and filter on my 766. All was working fine when I did the change. MCV pump seems fine at this point as I have clutch, steering etc. However no three point or remotes. I put 20 gallons in, and the stick is showing over full. 

Any tricks to getting the pump to pick up prime I should try? I followed the instructions for air in the lines per the manual, but didn't have any luck with that...

Thanks,

Greg

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5/8 wrench on the plug that points toward the rear on the *bottom *right side of the MCV.  Remove it. Start tractor.  Oil will Shoot out and all over the place, so Shut it of Fast, as soon as you see the oil fly. It only takes about .75 seconds.  Then put plug back in.  I would try that first, although, if it wasn’t primed I don’t believe you would have steering either, so unfortunately you may have something elsegoing on beyond my understanding. 

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1 hour ago, stronger800 said:

5/8 wrench on the plug that points toward the rear on the *bottom *right side of the MCV.  Remove it. Start tractor.  Oil will Shoot out and all over the place, so Shut it of Fast, as soon as you see the oil fly. It only takes about .75 seconds.  Then put plug back in.  I would try that first, although, if it wasn’t primed I don’t believe you would have steering either, so unfortunately you may have something elsegoing on beyond my understanding. 

That is just to bleed out the MCV pump circuit.  He states he has MCV functions, but not hitch pump functions.  This won't help him any unfortunately. 

 

 

I agree with a new o-ring on the filter base.  However, he would likely not have MCV functions either if it was sucking air there, as both pumps pull from the same filter housing.  

Pull the 3pt top cover off and see if any oil is running down from above.  It should be, but if there is and you have no functions, then perhaps the unloader valve is stuck open....

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6 hours ago, J-Mech said:

That is just to bleed out the MCV pump circuit.  He states he has MCV functions, but not hitch pump functions.  This won't help him any unfortunately. 

 

 

I agree with a new o-ring on the filter base.  However, he would likely not have MCV functions either if it was sucking air there, as both pumps pull from the same filter housing.  

Pull the 3pt top cover off and see if any oil is running down from above.  It should be, but if there is and you have no functions, then perhaps the unloader valve is stuck open....

Thanks for the info. Added detail the three point is currently raised, and will not go down...does that indicate anything additionally? I'll double check the filter, and then will figure out where the unloaded valve is and take a look at that.

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2 hours ago, gwoswald said:

Thanks for the info. Added detail the three point is currently raised, and will not go down...does that indicate anything additionally? I'll double check the filter, and then will figure out where the unloaded valve is and take a look at that.

Yes, 3pt up and won't go down is an interesting twist.  That is usually a separate problem entirely.  Anything else you left out?  

Why did you change the oil and filter?

So, if the 3pt won't lower, how do you know it won't raise?

Will it lower when the tractor is off? 

How are you testing the hydraulic remotes for function?  Did you plug a cylinder into them or do something else? 

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9 minutes ago, acem said:

What is your draft plan lever position? It can turn off the auxiliary hydraulics if fully forward. Thx-Ace 

The quadrant lever can turn off auxiliary, not draft control. 

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The three point is all the way up. Will not descend, tractor on or off. No problem with this prior to the fluid change.

I have a subsoiler on it. I had the fluid and filter because I hadn't changed it in the couple years I've owned it. Figured it was time and I had a few evenings to do it.

I tested the remotes by plugging into my 3 pt backhoe to use as a test cylinder. 

The draft control is forward, which is where it has been forever. I haven't touched it other than yesterday when I was fussing around trying to get stuff to work. 

If I run the quadrant lever all the way forward the engine note changes (sounds like the engine is unloading)

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Fixed it. 

So as I read through the suggestions and thoughts that the draft control can stop the remotes, I got to thinking about it. Last time I used the tractor, several weeks ago, I was using the subsoilers. I hit something large and popped the shear pin, figured enough for tonight, put the hitch in full lift, replaced the pin, and parked it. Decided that I had time and changed the oil this week.

So I was reading other forums and saw mention of the draft control levers getting wedged on a 1066.

So I popped the top link plate and took a look and sure enough, the draft control linkage was popped up beyond where it should be, so it was trying to lift full time. 

Anyway, that should be that. Thanks everyone for the help. I woulda been scratching my head for quite some time without the insight. Awesome forum as always.

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16 hours ago, J-Mech said:

Yes, 3pt up and won't go down is an interesting twist.  That is usually a separate problem entirely.  Anything else you left out?  

 

2 hours ago, gwoswald said:

Last time I used the tractor, several weeks ago, I was using the subsoilers. I hit something large and popped the shear pin,

And there it is. 

Glad you got it fixed!

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