More on the 856

old

Well-known Member
So since the MCV pressure sensor is not hooked up I tried to use my test light to see if I could get a pressure reading of sorts. Well hooked up the light and the light does not come on which tells me the sensor is bad since I would think not running it should be grounding to turn on the light?? Am I think correctly?? Also when running it is not on so figure the sensor is bad so where to find a replacement
 
Plus this. This 856 does not have a TA or if it does have one it does not have the control for it. Where the TA lever should be is a whole in the side of the hood
 
(quoted from post at 15:54:24 09/02/20) Plus this. This 856 does not have a TA or if it does have one it does not have the control for it. Where the TA lever should be is a whole in the side of the hood

If no TA or a TA delete kit has been installed whatever goes on with the MCV is MEANINGLESS as to the traction clutch working and the tractor moving.
 
This is a case of lack of steering and brakes and that is the problem I am trying to figure out and fix
 
Just because the lever is there does not mean the tractor does not have a TA. Many have removed the lever out of a misguided notion that if they can't be used they will not wear out.

There are two versions of the MCV. One has a plunger on top and a plunger on the back to shift the TA and dump hydraulic pressure to allow smooth shifting, respectively.

If I am not mistaken, the TA delete MCV does not have either of those, as there is no need to shift the TA, and no need to dump the TA pressure to shift.

If the TA was deleted, some things need to be done to the MCV.
 
Old IF the lever is missing. I would guess that either the TA is not working or has been deleted. See if the owner can tell you anything about that part. If they took it out in the past or if it quit working. Reason is in the main casting there are 3 tubes going to the TA if they removed it and didn't plug those holes that is why there is no steering. All the oil is flowing the easiest path through those holes and not getting to the other circuits. To check these holes you need to remove the MCV from the tractor. There will be four bolts approximately in the middle of the MCV that look like a rectangle those hold the pump to the back of the MCV 2 narrow then to lower at the same width as the higher ones about 2 inches apart sideways and about 5-6 inches up and down. You will also be able to check the o-rings on the pump connection at that time also. Those gaskets are pretty complex with the maze of cutouts and holes so that they would be more practical to buy than make. I have not bought any in a few years so not sure what the cost is now days. When you remove it I would use a couple of long bolts to slide it on both coming apart and going together. There is a plastic deal with a spring looks like a ball point pen spring in the bottom right corner that you don't want to damage nor the spring. That plastic deal a with the spring is supposed to be a oil leak thing so it can be steered without the engine running by trapping the oil in the circuit. I'm not sold it works. It also if I remember right has a couple short dowels it sets on. It is easier to get things in place with the long bolts or long dowels. I use ones about 4-6 inches long.
 
Is there an easy way to tell if it is a tractor that did not have a TA when built or if it has been deleted the correct way?
 
I'll have to go out and look at the serial number and see if it has the S or if it is missing the S. I hope it is missing the S but then it maybe a case of the guy who brought it to me put in the wrong MCV
 
So where is the serial number tag located at?? I just went out to look for it and it is was in plain site it sure wasn't where I could find it. I looked top to bottom front to back and did not see a tag. Only tag I saw was on the injection pump and it was partly painted over
 
Can you post pictures , i like pictures . So you say the T/A handle is MISSING ?? not there ?? is there linkage running down the left side of the dash support ?? that runs up to the top of the MCV and to a spool valve that goes up or down , Does it had the linkage that goes from the clutch rod back to a little valve on the back of the MCV above the sending unit ?? . You can remove the sending unit and plumb in a manual gauge and all ya need here is a 50-100 pound gauge as a good system will only have around 22 -24 PIS and a BAD system will have less then 18 . You and rustred are way in over your heads . Someone else was in there before you and messed it up and washed there hands of the deal and now DUMPED the problem on you because someone that knows how and has the stuff to find the problem will CHARGE them the going rate to make it right . I personally hate digging thru a problem someone else caused in there attempt to fix . I went thru this on three tractors. Two were done BY DEALERS and one by a know it all on a T/A job that went south a week after he did the work and would not stand behind his work . So take pictures of the left side of this tractor and a good close up of the MCV. everybody wants to be and expert and everybody knows, When Everybody does up to three T/A jobs a week for five to six months out year for 20 plus years Then you can become and expert . Have i ever screwed up YUP sure did and i was glad it was on one of my own tryen to rush the job to get the tractor in the field and i put a gear in backward in the speed trans . We ASSUME that this RAG your working on HAS -HAD a T/A in it . And IF someone took out a T/A to save about 200 bucks and they did not change out or block off ports all bets are off .
 
NO TA linkage at all. Yes this does seem to be a tractor where some one else has been into it if not maybe 2 or 3 others have been into it. I am now hearing that there can be 2 different MCVs one for a tractor with a TA and one for a tractor with out a TA right?? And yes it does appear I am in over my head on this one and may have to call the guy and tell him I can look the brakes over but due to the MCV problem area I am not set up to tackle that. As for a gauge in place of the sensor where might I find such a thing.
THANKS
 
Yep that is 100% Correct . MCV''s that came on tractors with a T/A have a Spool valve on the top left and a T/A Dump valve on the rear side about half way up on the valve that is moved by a long 1/4 inch bolt hooked to the clutch release rod . This dumps clutch lock up pressure off the two clutch pacs so you can get them out of gear . The other one for factory NON T/A's does not have either . Now being that i have only been around TWO Mistakes ofg buiying one I H tractor WITH OUT a T/A and My buddy buying the other and BOTH OF US CHEWING on them for Months and loading and unloading them at sale tryen to get the sold To get mine sold i bought a whole speed transmission With a knowen good T/A and all linkage pulled the serial plate off mine and put it on the one i got and STAMPED and and S -Y behind it and got it sold the next sale and Vowed i would Never again Buy or Delete a T/A for the meager difference in cost . So on the NON T/A MCV's i have never opened one up or had one off. I do know that the gskt's are different as when you get a gskt set it comes with BOTH .
 
I'll have to ask the guy how many people have tried to work on it and when and why they did and how he lost steering and brakes. It will try to steer just not as easy as it should be to steer
 
Take a look at what Rustred posted on tractor talk as he has PICTURES of the MCV on a 806 that he is tryen like you to find the magic pill and cure his problems . 806 and 856 are ALMOST the same just depending on S/N where a gear cut angle was changed . HE hooked up two gauges that will tell some but not all . For his problems to be dead on he needs the one test valve that you install and add a THIRD gauge and the fact that he like you does not have a flow rater to check GP_M.
 
I did see his post and did look at it but that was about all I did. I have not been able to find the serial number on this 856. If it is where I think it should be some one painted over it. The I-T manual says it is on the right side of the clutch housing and there is a small plate there held on with 2 bolt/screws which might be it but it is covered with red paint so impossible to read and not sure if I tried to remove the paint if I would also remove the numbers
 
the serial # is on left side on bell housing as in the pictures i have posted. look at the mcv and you will also see what you have. if that one is the same as mine its TA. or post your's. throw that sensor in the garbage and use a gauge as thats what hydraulic's is about is reading pressure differences not a crazy on and off light. like being in the dark room then someone turns the lights on, i can see clearly now! its not supposed to be on running unless u step on the clutch which causes the pressure to dump so you can shift and puts the light on. same idea as the old chevy oil sending units. maybe those will work as a try out even has the same 1/8 pipe thread. think they should.
 
the serial number is stamped into the plate. removing the paint shouldn't remove the number. probably will remove some of the background paint.
 
I-T manual says right side but either way I will look again and yes I figured that might be the timing window
 
This 856 doe not appear to have a TA and it has none of the linkage for a TA so not sure if pushing the clutch down would do that dump thing
 

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