Underload when starting 970 Case (Agri-king)

[Hittleconstruction]

Hello all,

This attempt two to see if anything sound familiar to anyone, with new information.

I have a 1970 Case 970 6 cylinder Diesel tractor with the the 12 speed power shift. SN:8660951

As it sits now when you try to start the tractor, making sure its in neutral the RPM's start to go up to idle up for about 1
second and then it is put under some kind of load and dies. The tractor does not try to move as if it were in gear. It doesn't
matter if the clutch is in or out. The throttle can be open full. it makes no difference.

Prior to it being in this condition. When it was cool out, like 50 and colder. You would start the tractor, it goes to idle and
would throttle up if you wanted. But until it warmed up enough, sometimes when you pushed the clutch peddle in it would acted
just like it is doing now. It just would feel like its being put under a load and then die, you could not set the throttle high
enough for it not to die. As long as you release the clutch it would run fine. Usually after it warmed up that would go away.

Then there were different instances If it was cool or cold out, 35 degrees or lower when it was put in reverse let out clutch it
would go under load and die, no matter how high the throttle. After it warmed up it would stop.

Brakes have never really worked, peddles are always just hard, even after I bled them.

So far since this happened I have service the tractor, Both Hydraulic filter, Both fuel filters, oil change, Air filter is about
1 month old. Made sure the Hydraulic oil is not over full, using the site glass. In the last year I have, new Hydraulic oil
from CASE and proper type(cant think of the name at the moment) cleaned the pickup tube screen. rebuilt PTO clutches, Rebuilt
Hydraulic pump, rebuilt lift cylinders

Decided to clean up the Valve body that is under your feet. Not sure what its called. But pulled up the plate your feet rest on,
removed valve body, took it apart and clean each piece, ran brushes
through the valve body. put all together and no change.

Today I decided to start by passing where the hydraulic lines where going to. I pulled the small line from the pump, I believe
it is steering and brakes. put a hose on the output ran back into fill hole. Started the tractor. No change.

Then went to the large line from the pump, worked my way through these items filter, then a valve that splits off, unhooked the
line after all that. and where it runs back to the tractor (should run the gears, valve body, clutch). Hooked my hose to it and
started the tractor and it started and idled just fine, each time and to that point.

So now I am concerned. I need to study my manual more to continue this diagnoses and see if I can narrow it down to one thing.

In the mean time I would appreciate any ideas you might have.

Thanks

 

[Roger Link]

You have a sticking spool in the power shift valve body or a clutch pack that has warped disc's, you need to put a set of 4 gauges on the marked ports on the valve body to see for sure which spool is sticking.

 

[jrobison]

Double check and make sure you havent gotten the transmission jammed. I recently bought a 1370 and had difficulty with the shift linkage, if you wind up getting into two different gears it will kill the engine the moment you let the clutch out. It took me about 20 minutes to figure out the shift linkage was jammed and repair it.

 

[Hittleconstruction]

I was kind of concerned about that to. Yesterday I tore it down to check everything in the gear box, and was able to confirm that the tractor is in Neutral.

No luck.

 

[Hittleconstruction]

Will that work even though it only runs for 30 seconds at best? If it would work what kind of gauges? Would it be like the oil filled pressure gauge?

 

[mEl]

You would have to watch the gauges immediately at startup, with the pedal pushed you should only have pressure on C-4 circuit, with pedal released, in first powershift C1-C2 are pressurized, second PS C1-C2 are pressurized ans third powershift C2-C3 are pressurized. There is no instance where more than two clutches are involved at a time. This is why it is important to have four gauges hooked up at a time. In your situation you only have a few seconds to see what is going on before it stalls. Does it stall with the clutch down at startup? Have you tried shifting quickly after a startup to see if it stays running in second or third or try reverse immediately after startup? If it stays running it will help you to look at the clutch combinations and see which clutch is not disengaging.

This post was edited by mEl on 08/14/2022 at 11:46 am.

 

[Roger Link]

put the power shift lever in 2nd or 3rd with the clutch pedal in the up position and the 4 speed in neutral and see if it still stalls the motor

 

[Hittleconstruction]

Yes it dies with the clutch in. It seems no different clutch in or out.

When you say in first powershift C1-C2 are pressurized:
1. start with clutch in and the shifter in first powershift and leave clutch in till it dies?
2. Start in neutral, depress clutch, put in 1st quickly?
3. Start in neutral, depress clutch, put in 1st quickly, let out clutch?

I did switch out C1 & C3 spools, springs and caps. No change

The day I starting having the major problems, I was going along and went to stop. As I pressed in the clutch. I immediately heard/felt the sound of it going to die (It was at about 85% throttle) so as fast
as I could I finish depressing the clutch and went from powershift 2 to power shift 1. If I remember correctly the tractor seemed to be lacking in power or being drug down by something. I finished what I was
doing, this took about 30 min. No its where it is now.

No I have not tried to quickly shift into a gear, will try that right now.

 

[Hittleconstruction]

I have not done the 4th powershift position. I know that the 1st and 2nd powershift position in gear with the clutch in will kill it.

I did just find out because of MEL question. That if I have it in 1st or 2nd powershift position. I can have the throttle say 50% and drop the clutch and can take off and it will run. will try the 3rd and 4th with the clutch in to see if that will work. Just starting it in those gears, clutch in but not releasing it.

 

[mEl]

Any advice I give on power shifts assumes the 4 speed in neutral, forget the 4 speed, it has nothing to do with the power shift, the power shift is a standalone unit, all your testing will be done in neutral 4 speed wise, If the engine bogs with the clutch down let it out and immediately shift to second PS and see if the engine pops up to speed, then third, then clutch down which is C4 applied, then reverse which is C2-C4 applied. I am fearful however that if you ran it for 30 minutes finishing a job with an extra clutch applied that you may have damage that will require a split, if your pressure checks range to range check out, you may be dealing with major clutch plate warpage from being engaged but being forced to slip because it wasn't supposed to be engaged in the travel speed you were using. One thing for sure, you are probably not going to hurt it any more than it is with simple guick testing. In the future, if anything happens like this again, stop and do no more work till the system is restored to proper operation

This post was edited by mEl on 08/14/2022 at 03:58 pm.

 

[Hittleconstruction]

I will not start with the clutch depressed and in any Powershift position. I will take off in the 1st and 2nd position. I did not
try reverse yet. I will have to get some gauges. Do you have a recommendation for some inexpensive gauges?

Do you think switching around the spools will have any testing values? Since spool C1 & C3 swap didnt have any change?

 

[Hittleconstruction]

What is the max pressure it will produce. Found some 300psi gauges. Didnt know if that is enough

 

[mEl]

600 Lb Gauges is what we normally use, for accuracy try to use a gauge that will read half scale, 180-210 is normal working pressure, Lube pressure will be in the 75 Lb area dropping to 0 clutch depressed, If you shop you can find decent liquid filled gauges for less than $20.00, grease gun hoses with an adapter will work but a little nicer would be ones long enough to sit in the seat and have them in good view, I have seen some on here who built nice multigauge manifolds out of aluminum stock.

This post was edited by mEl on 08/15/2022 at 08:58 am.

 

[Hittleconstruction]

Thank you very much! I had plan on just video recording the gauges. Gives me a chance to review and compare to other readings.

Thanks again. Will post after I get the gauges and have some readings.