2004 Cat 257b Drive problem

[Gregory A White]

I've been a member for a long time. My first post as I usually find my answer in other posts.
2004 Cat 257b (SLK00398) with 3200 hrs has an intermittent pause in the left track when trying to turn L & R, forward & reverse. This happens when the oil is warm to hot but works great when it is cold to cool. R track operates like it should regardless of oil temp. Also, the L track will not spin when pushing a heavy load while the R track does. I put it on blocks and both tracks work as they should with no load. It has ISO 46 hydraulic oil, new filter (no metal shavings in retired filter), no metal shavings in reservoir which I drained, and no external leaks. It is located in NW Georgia. Any help/suggestions would be greatly appreciated along with appreciation for help from you that you never knew about until now.

 

[Nige]

If the problem appears with increasing hydraulic system temperature then it would appear it could be internal leakage somewhere in the hystat system for the LH track. However you seem to have covered most of the bases alreay.

The only other thing I can think of is possibly the outboard bearing #4 on the track drive group.

 

[Gregory A White]

Thank you Nige. I failed to mention that this problem has been ongoing for about 250 hours now (2 years). Any chance it could be relief valve or cheap hydraulic oil oriented? It acts like a pressure relief valve is opening about every 2 seconds. My next move was going to be replacing the left drive motor. That isn't cheap so I am chasing down the "lesser" expensive fixes first. It is only used on my acreage.

 

[Nige]

I wouldn't suggest replacing anything unless data-driven diagnostics points you in that direction.
Firing the parts cannon can get real expensive real quick and in the worst case scenario not even provide a solution.

 

[dmitry_bulldozerman]

Thank you Nige. I failed to mention that this problem has been ongoing for about 250 hours now (2 years). Any chance it could be relief valve or cheap hydraulic oil oriented? It acts like a pressure relief valve is opening about every 2 seconds. My next move was going to be replacing the left drive motor. That isn't cheap so I am chasing down the "lesser" expensive fixes first. It is only used on my acreage.

Before changing the hydraulic motor, you should check the hydraulic system valves. You should try swapping the right and left Crossover Reliev and Makeup Valves, this is on the hydraulic pump.


And for your information, the hydraulic motors are equipped with brake packs with a brake piston, if the piston seals #7 on the left hydraulic motor are faulty, then it will not release the brakes well when hot.

 

[Nige]

An infra-red heat gun might help you spot something getting hotter than it should, or for comparing any given component on the left side with the corresponding component on the right.

You should try swapping the right and left Crossover Reliev and Makeup Valves, this is on the hydraulic pump.

I would one step further and suggest the you only swap the FWD ones to start with, and if that reveals no difference swap the back and then swap the REV valves. If that again shows no difference then swap those ones back again. Any process such as this you only want to swap one thing at a time.

 

[Gregory A White]

Thank you Nige and Dmitry. Looks like a tough job but, I'm going to try. I'm not a young man anymore.
I have 1 more question.
5 pressure lines going to the left (drive) joystick and 1 non pressure that is laying unattached on the bottom pan. What is the non pressure for and should it be attached somewhere?

 

[Nige]

5 pressure lines going to the left (drive) joystick and 1 non pressure that is laying unattached on the bottom pan. What is the non pressure for and should it be attached somewhere?

There should be 6 ports in the bottom of the pilot valve. This illustration isn't the greatest but it gives you an idea. If you can get a look at the lower side of the bottom plate where all the ports are can you see any letters or numbers marked on that plate.? Also which port of the six is plugged.?
Post a photo if you can.

Last question. Is your machine single speed or 2-speed.?

 

[Gregory A White]

Not a 2 speed and not hi-flow. I will look at the pilot when I'm back home.

 

[Gregory A White]

The line with the screwdriver touching is marked "D" on the bottom of the pilot valve and is also the one unattached laying on the pan. None are plugged.
SN# - SLK00398

 

[ThreeCW]

If you have a parts manual for your 257B, you should be able to look at the hydraulic hose routing diagrams to figure out what goes where. I’m kind of surprised that there is an open hydraulic hose coming off of the pilot valve. Is so, it must be very different than my 2006 242B pilot valve.

Disconnecting hydraulic hoses from the pilot valve can be a very challenging and messy affair. Have a look at my thread for a pilot valve leak repair. You should be able to pick up a few tips for working on those hoses.

See: https://www.heavyequipmentforums.com/threads/2006-cat-242b-pilot-valve-leak-repair.80611/

 

[ThreeCW]

Find attached a few schematics from parts.cat.com of the pilot valves, return manifold and hydraulic tank.

Each pilot valve has 6 hydraulic lines connecting to them. I believe the one larger line from each pilot valve is connected to the return manifold (picture #3) which then returns fluid to the hydraulic tank (picture 4).

I am also thinking that the hydraulic tank drain line would be the "unattached line laying on the pan". That open line is most likely Item #1 shown in picture 3.

According to the schematics, that should be should be the way your pilot lines are connected.

 

[Gregory A White]

If you have a parts manual for your 257B, you should be able to look at the hydraulic hose routing diagrams to figure out what goes where. I’m kind of surprised that there is an open hydraulic hose coming off of the pilot valve. Is so, it must be very different than my 2006 242B pilot valve.

Disconnecting hydraulic hoses from the pilot valve can be a very challenging and messy affair. Have a look at my thread for a pilot valve leak repair. You should be able to pick up a few tips for working on those hoses.

See: https://www.heavyequipmentforums.com/threads/2006-cat-242b-pilot-valve-leak-repair.80611/

It is laying "open butt" on the pan with no obvious leakage. It is a larger diameter than the other 5 lines. I will trace it again to be sure and use your pics to try to determine where it should be attached and "why" it is where it is. It looks to be the same as your 242B valve.

 

[Nige]

It looks to be the same as your 242B valve.

It will be. Your 257B has the same part number of hystat pilot valves as a 242B.

If that line is in fact the return to tank I have to wonder how the LH pilot control valve is even working. That line should be carrying oil back to the tank any time the joystick is in the neutral position. If the line is simply lying open on the floor surely there must be a plug in the 6th port in the bottom of the pilot valve.?

Attached the parts illustration of the LH pilot lines clearly showing 6 hoses that are attached to the bottom side of the pilot valve. You can see the end of the Hose #6 that I'm surmising will attach to a return manifold somewhere in the right side of the machine. In fact it is illustrated on the RH pilot lines drawing.

I wonder if someone has been in that pilot valve previously and could have possibly reassembled it incorrectly.? Or even whether the pilot valve that is in there right now is not even the one it's supposed to be - i.e. non-original.

I wouldn't suggest to go any further with the "drive problem" until you get this issue resolved.

 

[Mobiltech]

I know you have probably already checked but do you possibly have some track internal drive lugs missing. When you say it pauses every 2 seconds makes me think of either the sprocket slipping in one spot of the track travel or one bad piston/ roller in the track drive motor.
These drive motors have no planetary and turns at the speed of the sprocket so every 2 seconds would be about one revolution.

 

[crowe2007]

On a cat 299d3 got a code 41-4 and a 458-3

 

[crowe2007]

Can you help me

 

[Nige]

Can you help me

Please can you create a new thread in the Compact Track/Multi-Terrain Loader section and mention the machine Serial Number. It makes it easier to look up information. For information on how to create a thread, click this LINK

 

[Gregory A White]

I know you have probably already checked but do you possibly have some track internal drive lugs missing. When you say it pauses every 2 seconds makes me think of either the sprocket slipping in one spot of the track travel or one bad piston/ roller in the track drive motor.
These drive motors have no planetary and turns at the speed of the sprocket so every 2 seconds would be about one revolution.

I got the return line issue figured out. Someone put a “tee” in the return hose and the open hose on the pan was installed on the tee. It was hidden in all the sludge. The open hose had a piece of round stock in it so it didn’t leak. I guess the return must be low pressure. I did check the track and rollers and gave it a good bath. Also checked all electrical connections. I’ve gone about as far as a parts changer can go. Should something else come to mind that I need to check, feel free to hit me with it.

 

[Nige]

I guess the return must be low pressure.

Correct. It's probably so low that no gauge would measure it.