Case 1150 loader clutch pressure problems

[Anonymous-0]

At first blush, erratic clutch pressure. After much observation there is a pattern.
1. Constant below normal (260-290) operating pressure--it jumps immediately to 200psi indicated upon starting engine and remains at 200psi indicated from 800rpm to 3000rpm. Shifting ANY control lever causes psi to instantly drop to either zero or 100psi indicated.
I say "indicated" because the tractor continues to function normally at either zero or 100psi with the one exception that at zero it does not turn as well as it does at higher indicated psi.
2. Shifting either the HI-Lo or Forward-/Reverse levers back and forth slowly after the indicated psi has dropped to either zero or 100 will cause the psi to instantly jump back to 200.
3. These "jumps" are exactly that. The psi does not slowly rise or fall--it jumps instantly. Engine rpm has no effect on the indicated clutch pressure.
4 I have had both the pressure regulating valves apart and have found nothing wrong (Torque Converter pressure regulator valve and Clutch/Transmission pressure relief valve). All filters have been replaced AND the oil was clean and without water--no debris, metal parts, dirt, etc. in any of the filters or housings.
5. Low initial indicated psi may be the charge pump (I have a new one) Zero indicated psi is probably not correct, as the tractor should not move at zero clutch pressure, and it moves rather handily at "zero". It will even perform a counter-rotation turn at zero indicated psi.--just not quite as well as it should.
6. This is a military surplus machine with military refurbishing. It looks NEW. It has 390 hours on the rebuild by the military. The military part of all this is important because Case can't find the right parts, due most likely to different specs for the military than for civilian tractors. (EXAMPLE: This machine is supposed to have a Case 401B 6 cylinder engine, but it has a Detroit 4-53 engine and related parts which Case can't find in their service manuals and parts books.)
7. The Winch works fine. It operates off the left side forward/reverse drive clutch, but not like the book says. Instead of a 3 position (F-N-R) Winch lever and in or out by the clutch, it has an in or out Winch lever and direction is controlled by the forward/revers lever in the transmission control lever tower. But the fact is the Winch is strong, indicating there is nothing wrong with the clutch.
8. The way the indicated clutch pressure snaps back and forth between zero, 100psi, and 200psi makes it appear that some kind of shuttle, or valve is snapping open or closed when gear levers are moved. I suspect the transmission control valve or some related part I can't find since the pressure changes occur only when the control valve levers are operated. (There is, I believe, some FLOW impairment when the pressure is at zero because the tractor can lose momentum pushing a big load or climbing up a 45 degree pile. Under those conditions I can encourage better performance by more throttle--without changing the indicated pressure. Flow loss could fall back on the charge pump, of course....) Still, that does not explain the jumping around of the indicated clutch pressure. 200psi to zero and back to 200psi are big jumps to be accomplished instantly.
9. Does anybody know what is going on with this machine? I have owned and operated Caterpillar D8s and D6s and a couple of International TD14s in the past 50 years, but this is my first Case. I don't know its idiosyncrasies.

 

[george md]

Henry,

If it is a plain 1150 ,I should be of some
help. 1000 and 1150 have the same trans and
I have several 1000's. Also have friends with
1150's that I work on.

Early 1150's had A401D engines , later ones
had 401BD , military loved detroits for some
unknown reason. With a 53 series you are not
going to sneak up on someone.

Symptoms sound like a leak in the suction
line from the trans to the charge pump,probably
above the oil level in the trans or it would
leak when not running. Could be the filter can
or the rubber coupling (vibration eliminator)
with loose hose clamps.

Normal trans pressure is 175 - 225 psi,
converter can run 40 - 80. Leak in suction
line would make press erratic and the oil in
the converter foamy and not drive properly.

Send me an email with a phone # and I'll
call you.

george

 

[mEl]

We had 1150 series loaders at work , over the years I have found many of the transmission related pressure problems on several different units were caused by the modulator piston assembly not being seated properly by it's linkage.

The linkage at the clutch pedals can get tight or the rod bend that goes from there to the modulator piston. This would be the first place I would look.

If you have a service manual that you can access, one of the plugs on the valve cover contains a nylon screen that you could look at. Also the service manual contains a procedure for properly adjusting the modulator piston. It,s the first check I would make.

mEl

 

[Anonymous-0]

George

You're right about the noise--maybe the military was out to scare the opposition rather than sneak up on them.....

I took the filter apart and put it back together looking for a leak there, but it seemed fine, and I tightened it down securely.

It is supposed to stop raining here in a couple of days (it snowed last night), and when it does I will pull the seat and floorboards and check it all out again. I have both a parts manual and a service manual for the machine--the parts manual being the more useful and informative of the two.

The machine is a plain 1150 near the end of the series--SN 7302083. (I think there were only about 900 more made before Case discovered the A, B, Cs.)

Finally, all fittings and hose connections are dry, so there are no obvious leak points. (I would think that even though it is a suction system we're discussing, the fluid would stay in the line when the tractor shuts down and leak out any holes that exist.)

 

[george md]

When you shut down the engine ,if there is a
leak above oil level the oil will return to
trans as there is no check valve to hold it
up in the line.

Getting lazy on up hill push is a sign of
sucking air . I rarely disagree with mel ,
but I don't think plain 1150 has a modulator
valve , they came on the later tractors.

george

 

[mEl]

(quoted from post at 11:21:23 06/01/14)
When you shut down the engine ,if there is a
leak above oil level the oil will return to
trans as there is no check valve to hold it
up in the line.

Getting lazy on up hill push is a sign of
sucking air . I rarely disagree with mel ,
but I don't think plain 1150 has a modulator
valve , they came on the later tractors.

george

George,

Please don't be concerned about disagreeing with me.

I guess when we see problems brought up it is just natural to work in our sphere of experience.

I have worked more with the E's than anything else.

 

[george md]

Mel,

I have an 855D in the shop that has me stumped,
Has new oil control rings on the F/R shaft and the
sleeve (cap ) is on size and no wear grooves, but
when going forward it gains pressure in rev . when in rev it works properly . I have service
books on most of the older machines , but nothing
with a modulator valve , am I guessing right
that it is a problem ,and what to look for?

george

 

[mEl]

George,

I would think the spool would be return to sump on the opposite direction position in the main cotrol valve so I would lean toward a fault in the modulator as well.

That system has been so trouble free over the years that I have never had one apart.

The other issue which you are probably very familiar with is the spool snap ring failure in the main spool valve for the tranny but I cannot think that you would be getting a f/r shift at all with that problem.

Keep me posted.

 

[Anonymous-0]

George

I was trying not to appear any dumber than absolutely necessary, so I searched at length for a "modulator valve" in my parts manual and my service manual and my operator's manual before responding to mEl. I could find no trace of such a thing and must concur with your suggestion that those appeared on later models. However, my search for the "Modulator valve" led me to the Declutch Lockout Valve, which I had completely forgotten, but which once existed on this tractor.
I had read about it in my operator's manual so knew what it was when I found it, but it was taken out of the system at some past point in time and is no longer connected to anything, and the pushrod knob has been removed.(Probably to keep anyone from thinking it would work)

I still intend to go leak hunting but wonder if tampering with the system by removing this clutch lockout could have caused some unintended side effect. ? All I know about a Case is which end to point at the dirt, but I see from the schematic that the clutch lockout is connected to the brake master and slave cylinders which devices, in turn, disengage the clutches (which operate by "clutch pressure" which in my case [No pun intended]ranges from somewhat lacking to non- existent). I don't use the brakes to turn, so they have had nothing to do with the pressure drops and rises, and when I have occasionally used them both at once to stop, I haven't noticed any change in clutch pressure.

Oh, yes. I forgot to mention...converter pressure is good. It is about 60psi on cold startup and runs at about 50psi when warmed up. It does not fluctuate. All the temperatures stay well within normal operating ranges.

Henry T

 

[mEl]

Henry, If I am correct the converter pressure is set up by the overflow of the main regulator , a systen which I would refer to as a cascading system where the return oil from the main regulator is once again run through a regulator valve that of course operates at a lower presure than the first.

My suggestion would be to get an accurate test gage to get an accurate reading of main relief pressure. I am quite certain that the system could be flo tested using a tee test procedure to watch individual clutch leakoffs.

 

[Anonymous-0]

George

Thanks for the information so far. I finally got around to taking the tractor apart again. While all of the foregoing communication was taking place I was waiting for a filter kit which finally arrived. As before, I could find nothing that appeared unusual. BUT...when I installed the new filter screen and O ring, I found the vacuum leak. The old O ring was....wrong, worn out, or defective. When I took the filter unit apart before and put it back together it screwed together with no resistance. The new O ring caused considerable resistance when it encountered the housing when the canister was being screwed in with the new filter and O ring.

I haven't done an actual work test, but sitting in place the machine did not experience any pressure drop upon shifting either track, or both, from forward to reverse or reverse to forward. Shifting the hi-lo levers likewise caused no pressure drop. I am cautiously optimistic. Your advice was right on.

All this now brings me to another question(s). You mentioned that the clutch pressure should be between 175 and 225 psi. Here I will preface my question with the caveat that I have encountered numerous discrepancies between my operator's manual, service manual, parts manual and the actual tractor. (Engine not the same, tachometer not the same, filter screen not the same, winch does not operate as described, etc.) My question is: Why 175 to 225 psi charge pump pressure ? The book says 260 to 290psi. As I mentioned earlier, the machine seems to work fine at either 100psi or 200psi, so a normal operating pressure of 175 to 225psi would seem to work and 200psi would be exactly mid-orange. According to the books there are two possible charge pumps for this machine and two torque converters. My tractor (loader) apparently has torque converter model D 52081 and its appropriate pump--Model D 49432. The pump is, without a doubt, a D49432, so I have to assume the appropriate converter model. Does your 175 to 225 depend upon the converter/pump combination ?

Finally, If the tractor is actually supposed to operate at 260 to 290psi clutch pressure, and, instead, it operates at a considerably lower (200psi) pressure, does that have any adverse effect on the clutches? (The key word here is "operates". The machine seems to work fine at 200psi.)