1980 D3 Caterpillar not steering

Babbilonian

New User
I recently bought a 1980 D3 Caterpillar that had been overhauled at Western States. Engine rebuild, brakes replaced, clutches replaced, trans pump tested (300 psi), cylinders and hydraulic pump rebuilt, etc. This was about 25 service hours ago.

When I start it and begin to use it, it works perfectly, but as it warms up, the steering clutches do not seem to disengage. I have to press the pedal all the way to the brakes to get any steering and there is a groan from the brakes (or something). It is apparent that the machine is fighting the drive on both sides when attempting to steer because it takes a lot of power to get it to turn.

The transmission filter was replaced durring the PM at Western durring the overhaul.

What would make it stop working when it got warm?

Thank you all very much for any information or experience in this.... The War Department is pretty upset this purchase needs work. ha ha.
 


Welcome to the Forums.

You don't say if you purchased it from Western States after the overhaul or did you have them do the listed work after you purchased it? With only about 25 hours on it since the work was done, I would start by at least talking with them about the problem.
 
Thanks for the welcome. These things are
fun...

I bought it from a guy, who bought it from
a guy who had the work done. I do have the
receipts. The guy i got it from sold it to
me discounted because he didn't want to
deal with it.

I called Western and they actually
remembered the machine, but the old timer
that worked on it in 2020 had retired and
the tech I talked to didn't know much
about it. He looked around and said the
machine was so old that they had thrown
away the shop manuals in a move...

What I am wondering is if they had tested
the transmission oil pressure cold, and
that being good moved on and never tested
it warmed up and If the pump in the
transmission is weak.

Does anyone know if there is an adjustment
on the clutches?
 
That machine is far to new for me to know much about but it sounds more like a steering clutch problem than a transmission problem.
Could be a simple steering clutch adjustment.
 
(quoted from post at 07:03:44 03/20/23) That machine is far to new for me to know much about but it sounds more like a steering clutch problem than a transmission problem.
Could be a simple steering clutch adjustment.


That's what i was hoping, but so far, after pulling the deck plates (not alot exposed that way) i dont see anything for a clutch adjustment. Only brakes.

Couldnt imagine there not being an adjustment. I still have to put a guage on and test the preassure cold and hot...
 
(quoted from post at 10:13:12 03/20/23)
(quoted from post at 07:03:44 03/20/23) That machine is far to new for me to know much about but it sounds more like a steering clutch problem than a transmission problem.
Could be a simple steering clutch adjustment.


That's what i was hoping, but so far, after pulling the deck plates (not alot exposed that way) i dont see anything for a clutch adjustment. Only brakes.

Couldnt imagine there not being an adjustment. I still have to put a guage on and test the preassure cold and hot...

If you don't have the Operator's and Service manuals, I suggest looking into getting them. They will prove to be worthwhile investments. There is a CAT parts site online where you can look at the parts book for your machine. You do need the serial number to use it.
 
If you take a look at the thread where you started I explained about the the pressure test you need to do, found on the outside of the bevel gear case. you should do this test both cold and hot. Because you get tough steering in both directions it's likely a common denominator problem, likely pressure (fed off the trans) to release the clutches. Yes, you can adjust the steering clutches but you have to open up the back end (from on top) to do it. This adjustment is not likely the problem because it works fine on start up. Another check point is on the pedal valves but that's unlikely because both sides show the symptoms at the same time. I'm no great expert but I have had four of these machines and I've had the back end opened up on more than one occasion, so I guess I can say 'been there done that'. The groaning sound is telltale that the clutches aren't fully releasing. In addition, if your brake bands are nearly worn out, this also makes for harder steering. What I also did was, after removing the 'steel lids' on top of the bevel gear case, starting up the machine and activating the clutches to see what's going on. If you decide on the external pressure check, like I said, go back to your first post and read my details there.
Please let us know your progress.
 
Check the small bearings on the end of the steering clutch control valve spools. These little bearings are known to fail and when they do they allow pressure loss to the steering clutches due to inaccurate spool control.
There isn't much of an adjustment to the steering clutches. The only adjustment available is the yoke stop bolt mounted to the yoke arm.
Internal leakage of the steering clutch control valves will also cause loss of control pressure. If new seals don't fix it the spool valves are worn out and will need replacing.
 
(reply to post at 22:08:47 03/20/23)

Thank you all for your assistance...

When you say internal leak in the control valve, are you talking about the valve at the front end near the steering pedal? Where does it leak to? The set up on mine does not appear to have any bearings. It is just a round plunger that contacts the pedal control arm about 1/4 of an inch into its movement. I'll have to look for surre how it is attached but it moves along with the pedal until the brakes apply by movement of that draglink to the brakes. There are supply hoses that come out of a t fitting from the transmission to each side and then back to the clutches, but nothing is leaking along the way. The supply hoses flex with the pedal movement...

I spoke with a mechanic who doesnt think there are clutch adjustments, that it is all hydraulic and that it is probably a leak in the pump inside the transmission that gets worse as viscosity drops.

Test guage is on the way to see what's going on...

Thanks again guys.
 
The only thing I've had go wrong with a pedal valve is an internal spring having broken, cost $2 to replace and full pressure was back. Any external leak is visible around there. Again, I don't think you have a problem at that point because both sides seem to malfunction at the same time.You can get leaks from the hyd. cylinders, internally, that release the clutches. If they leak, the oil comes out the bottom of the bevel gear case, providing you have dry clutches which I believe to be the case. Again, this would not be the case with both at the same time as the cause of malfunction.

Thank you all for your assistance...

When you say internal leak in the control valve, are you talking about the valve at the front end near the steering pedal? Where does it leak to? The set up on mine does not appear to have any bearings. It is just a round plunger that contacts the pedal control arm about 1/4 of an inch into its movement. I'll have to look for surre how it is attached but it moves along with the pedal until the brakes apply by movement of that draglink to the brakes. There are supply hoses that come out of a t fitting from the transmission to each side and then back to the clutches, but nothing is leaking along the way. The supply hoses flex with the pedal movement...

I spoke with a mechanic who doesnt think there are clutch adjustments, that it is all hydraulic and that it is probably a leak in the pump inside the transmission that gets worse as viscosity drops.

Test guage is on the way to see what's going on...

Thanks again guys.[/quote]
 
Early D3's just had a straight spool (no bearing) Later versions D3B uses the bearings.
Would help if you posted s/n.
The steering clutch control valves are a balance type valve, depending on correct position to control pressure. Internal leakage would bleed off internally through the return to sump port.
Not uncommon to see these early valves worn out.
 
Well, Old Magnet was right. It seems that the valve wore out and the oil leaks past when it gets hot and looses preasure. Caterpillar wants $6500 for a new one, but they are on backorder. Does anyone know of a good supplier of used or after-market parts for this? I'm guessing that the part is not rebuildable, but has anyone heard of a rebuilder or know where to get a rebuilt one?

The part number is: 3P34370
The SN of the Cat is: 82U0298

Thanks,

n.
 

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