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.
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.
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.
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.
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.
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. 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.
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?
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.?
Not a 2 speed and not hi-flow. I will look at the pilot when I'm back home.
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
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: HeavyEquipmentForums
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.
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.
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.
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.
On a cat 299d3 got a code 41-4 and a 458-3
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
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.
Correct. It's probably so low that no gauge would measure it.
The sn is cat0299DPBX903102
Start a new thread for your issue. Trying to diagnose 2 very different machines with 2 different issues in the same thread leads to nothing but confusion for everyone.
After you guys suggestions and what I have done, I am leaning toward an internal leak. That isn't going to be an easy one for me. Is there a "most likely" suspect? I am going to start with the LH joystick valve. There is a tiny bit of oil around the plungers just under the handle. Could this be classified an internal leak? I'm having a blast dealing with this thing (I love tinkering) and learning so much from all of you.
This issue has been going on for a couple of years (approx 250 hrs) and not getting any worse. I'm having a difficult time believing that drive motor is the problem.
Resealing the joystick should not be a difficult task provided you are reasonably handy with tools. Just remember that it is a hydraulic compone built to tight tolerances. Don't go bashing the internal, or external for that matter, parts with hammers.....!! @ThreeCW did a really good write up of how to strip and rebuild a pilot control valve. He put a link to it in Post #11 on Page 1. You could do far worse than copy exactly what he did. Attached is what the service manual covers, but that does not include the actual disassembly of the guts of the pilot valve. However I did find rebuild instructions for a track dozer pilot valve that uses the same repair kit as the skid steer. Before you do that though, I think you should investigate thoroughly the suggestion from @Mobiltech in Post #15 on Page 1 regarding the possibility of a missing track drive lug or lugs.
Gregory, My pilot valve leak repair was eventually addressed by changing one "O" Ring in the middle of the pilot valve assembly. If you are going to address a leak in the top part of the pilot valve assembly, a MUST READ from a top contributor and an Administrator of the HEF, Willie59, is located here: HeavyEquipmentForums In this thread, Willie59 points out: "Remember, when you disassemble the unit, be sure and note which spring/spool set came from which hole, don't switch the location of those parts or mix them up." I did not have to go into the top end of my pilot valve but did read this post a number of times before attempting my repair. Very good advice indeed Willie !!
Thank you Nige. I will follow your suggestions. I respect your knowledge. Thank you 3CW. I will definitely read the post from Willie. A few days back, I put extra effort in cleaning the radiator fins to assure good air flow and cooling of the hydraulic oil. I ran the Cat a couple of hours yesterday. It worked well at first but, after 1/2 hour, left track began to stutter again. The leak around the joystick plungers is tiny but, I'm wondering if that could be enough leak to cause the problem? As you can tell, I'm not familiar enough with hydraulics to diagnose this but, I am having a ball trying and you guys help is extremely appreciated.
Hello. This problem cannot be caused by a tiny leak in the joystick. But this problem can be caused by a tiny break in the seal on the brake piston of the hydraulic motor. I wrote to you about this above and attached a diagram of the hydraulic motor.
I’m beginning to accept that it is probably the motor. Is rebuilding the motor something a pretty good DIYer could do?
I printed the diagram.
Have you at least ran some test to determine the motor is NFG? Tossing parts at something gets costly quickly. A failing drive pump will give you similar symptoms. I'd at least run a case drain flow check on the motor before condeming it. Get the hydraulic oil warmed up, then remove and plug the case drain hose at the motor you are testing. ONLY plug the machine side - leave the motor side open. Connect a hose to the case drain fitting on the motor and put it into a bucket. Stall out the motor and give it full travel pressure. I don't believe CAT has a spec on case drain volume per minute but one of their tech guys once told me that a good motor will trickle out a pencil lead sized stream at operating temperature. If the motor is shot then oil will be pouring out of the case drain.
I've torn apart a couple CAT skid steer travel motors to confirm failures. I don't know your level of mechanical ability but I would say it'd test the abilities of the average DIYer.
So, I put the skid steer up on blocks with tracks off the ground. Tracks operated as they should. I put a 10,000 lb strap on the problem track to simulate the force of moving the machine on the ground. It did not pulsate at all. Added engine rpm’s and thought it was going to tear thru the track. Still no pulsating. When back on the ground, put it against a tree and pushed. The right track spun on the dirt but the left would not. Could I have a bad relief valve for the left track? If so, which would it be on the main valve? It did the same in reverse
Did you measure the case drain volume when you did this? If not you wasted your time and didn't learn anything new.
The case drain test produced a steady stream the size of a pencil or more. If I did it correctly, it drained approx 9 gallons in about an hour. I went ahead and pulled the motor out. I have the motor part # as 280-7862. Is that correct for 2004 Cat 257B SLK00398?
I'd be checking the pump next before throwing a motor at it. Case drain leakage from the motor doesn't seem to be too terrible.
Thanx for the advice. This is exhausting. Am I looking for pressure or volume when checking the pump? Or both? Point me in the right direction.
@Nige would be the fellow to ask for specifics. I unfortunately lost access to SIS when I got laid off from the dealer a few years ago. Everything I've mentioned so far was going off my memory the best I could.
Attached are the Test & Adjust and Troubleshooting procedures for the hydrostatic drive system.
Dmitry, can you give me the part # for the brake piston seal (#7) you mentioned earlier. If you have a parts diagram for the entire motor, i would appreciate that. I am rebuilding the drive motor and that seal #7 looks pretty worn.
Nige, I have a guy coming this week to check and test the pump. I don't have the tools.
Greg, there are two different styles of motor depending on when the machine was built. The illustration that Dmitry posted and I repeat below was for a "Type 2" motor. Your Serial Number is a very early machine and, by Serial Number should have "Type 1" motors. The Type 1 motor parts breakdown does not show anything for the piston brake seals. The Type 2 motor was installed from the factory only on SLK-prefix machines with S/N above 6250. See attached. The only thing I can suggest is to look for a data plate on your motor with the Cat Part Number on it. 222-5662 is what it should have by machine Serial Number. The later Part Number is 280-7862. The only other thing I can think of off-hand is that these motors were built for Cat by Rexroth. It may be that if Rexroth model details can be found that parts can be obtained outside the Cat parts system
I think the correct hydraulic motor number is 222-5662, since the machine was manufactured on 08/01/2004. And the 218-6631 group is relevant for 2004. Separately, the brake piston seal numbers are not indicated in SIS, but there is a number for a set of seals for repairing the hydraulic motor, 268-1933 KIT-SEAL (INCLUDES SEALS & GASKET).
I’m still wondering how you did a case drain test for an hour to get 9 gallons. This motor needs to be stalled a full drive pressure to do the test. You also need to stall it in multiple positions of travel to do it correctly. This motor makes one revolution for each revolution of the sprocket.
You make a good point. I just assumed an amount was measured for a minute and then multiplied by 60 to get that number.
For clarity, is the motor number that you refer to in Post #35 noted above from the actual motor plate?
If it is then the news might be a little more promising......... The attached is the parts breakdown. Unfortunately I can't see a detailed breakdown anywhere of the 289-6343 Seal Kit.
I cannot locate a part number anywhere on my motor. The diagram Nige sent me is very similar to my motor and the seal in my motor is not an “O” ring. I found a number stamped in the edge of the mounting plate C779956. 10 03 stamped about 2” away. I can’t find that number anywhere on the internet. PS- Thank all of you for sticking with me in this very long thread.
Forgot. REXROTH is stamped on it.
Well Mobiltech, I blew that test. It drained the reservoir tank.. The brake piston was kind of in a tiny bit of bind when I took it out. I put a light air pressure in and it came loose then I used a magnet to pull it out. The seal isn’t broken but definitely needs to be replaced.
So where exactly did the 280-7862 Part Number come from.? You were the one who originally mentioned it.
280-7862 replaced the 222-5662. My motor is no longer available according to Catparts.com
Hard to tell from those pics what the pistons look like . The pistons are what the rollers are mounted on. Can you see any scoring on the pistons?
I haven’t gotten to that yet. One of the rollers was stuck. I pulled the rest out with a magnet. Finally got the stuck one out. I believe the stuck roller along with the bad seal on the brake piston may well be my problem cause the pulsating of the track. What is your opinion?
While everything in that statement is technically correct that does not mean that the motor on your machine is a 280-7862. In fact based on the information that I mentioned earlier it is more likely to be 222-5662, a motor for which only a limited number of repair parts are available. Unfortunately that does not include the brake piston seal. I would hazard a guess that the only way you might get parts is via a Rexroth dealer.
Yes one piston sticking could be the problem. If it shows any sign of scoring that would be bad.
You are correct Nige. I tried to order the motor #222-5662 from Cat. It has been replaced by part # 280-7862 thru Caterpillar. Mobiltech, That stuck piston seal/square "o"ring was in pieces. No scarring on any of the 8 pistons or piston wall. I am now trying to locate the piston "O" rings but, even Bosch Rexroth is having problems locating. They can't even give me the part number or size of the piston "o" rings. I am going to Grainger Supply to see if I can find them there. I phoned Caterpillar to no avail. I may have to buy a motor because of this.
Photos of the piston rings/seals
There is no need to buy an engine because of two piston seals. I think these seals can be found by selection. And theoretically, the 268-1933 KIT-SEAL (INCLUDES SEALS & GASKET) should contain all the sealing rings and gaskets, including the piston.
As complete assemblies the old & new motor Part Numbers are interchangeable, despite the internal parts being different for each one. The contents of the 268-1933 Seal Kit are as follows: - 1 x 3E-6708 Seal, O-Ring 1 x 207-9718 Gasket 1 x 3J-7354 Seal, O-Ring 1 x 3K0360 Seal, O-Ring No brake piston seal. Sorry about that. Can you give some basic measurements of the piston seal; as a minimum inside diameter and cross-section (in millimatres please) as near as you can measure. Is the cross-section square or rectangular.? If it is rectangular then you will need both height and width. There may just be a Cat piston seal P/N hiding somewhere in the Parts system that might fit as an alternative.
It is square.
Thanks for the measurements. I will go digging but it may take a while and even then I might turn up nothing. Question. In the photos accompanying Post #59 on the previous page the seal looked a lot bigger than 1.5" Inside Diameter. Can you conform that measurement please.
Those measurements are very close. It measures 1 7/16” on the piston groove and that is a tight measurement. The seal itself has the gap in it so it measures 1 1/2”. That gap is for expanding the “rigid” o ring to install it on the piston. And those pictures were zoomed in to get a better close-up view.
I think you will have to go to a hydraulic shop that services rexroth for those seals. Cat is famous for not giving a complete breakdown of parts for items they don't make themselves. Here is some interesting info on the rexroth radial piston motor.
Sorry but no it isn't. That seal should be a perfect circle with no break in it. A new one will be much softer than your one that by now has worked for hundreds of hours in hot oil and hardened as a result. The normal way of installing a seal like that is to drop it in some boiuling water to soften it then "persuade" it over the piston until it drops into the groove. TBH I like Mobiltech's idea of taking the piston and seal to a Rexroth agent and have them try to identify it.
Wow Nige, I was fooled again by this thing. Each and every ring has the same gap except the one I took out in pieces. THAT bit of info will make this easier on me IF those rings need to be continuous.
With that said, what are the chances the rings for the 268-7862 motor would work? Or is it built the same as this one?
Unfortunately no. The brake piston seal on the 280-7862 is a different size to yours. If you look at the illustration of the two motors they are very different despite being interchangeable as complete units.
Posts #48 and #49 mentioned the only ID on this motor is Rexroth C779956. I had a pretty deep look online and could find not reference to this motor. What about the drive motor on the other side ... does it have any identification plates on it?
I found a really good tear down video on a Rexroth MCR-T Radial Piston Motor. In the video at about 27:30 min:sec, the mechanic starts to remove the piston assembly. At 28:00 min:sec, he removes a piston and roller and comments that "you can't buy the seal, you have to buy the piston and roller section as a pair". I have not watched the rebuild video yet, but perhaps you can get some more information when he reassembles the piston assembly. Based on this video by a mechanic who has done many of these repairs, I'm thinking that the square seal rings you are looking for may not be readily available.
This comment #72 will hopefully be the last. I ordered some rings from CRC Industrial. They are supposed to be here 2nd week of November. If it works, great. If not, I’m going to buy a new motor. You gentlemen have been awesome and patient with me. Your knowledge has impressed me tremendously and words can’t express my sincere appreciation. I figure I have made your eyes roll a few times but you stayed the course. That is my opinion of a MAN! I’ve found myself calling you gentlemen “a friend of mine” more than once.