jd350c reverser problem
jd350c reverser problem
adjusting psi on newly rebuilt unit-sn calls for 150psi-using new springs-had 90psi starting-added shims in stages-got to 130-added .024 and shoot up to 290psi- have tried several combos- keeps shooting up after 130- never had this problem before making psi adj- any thoughts- thanks
Make sure you are using the right test port for you pressures on the engagement pressure. Should be an 1/8" pipe plug top center of the valve body.
How many shims have you added? Which valve did you add the shims to? I will have to get my manual out to remember which plug on the valve body is the engagement valve but I think it should be the front one. I have never had to add more than two shims to the original set that was already in the valve. Usually a couple of the thick shims and then a couple of the thinner ones is all that should be required to get the desired pressure.
I'm wondering if you are shimming the wrong valve. 130 psi is not all that bad although the "C" series did call for more pressure because they use the reserve pressure from the reverser to engage the steering clutches.
How many shims have you added? Which valve did you add the shims to? I will have to get my manual out to remember which plug on the valve body is the engagement valve but I think it should be the front one. I have never had to add more than two shims to the original set that was already in the valve. Usually a couple of the thick shims and then a couple of the thinner ones is all that should be required to get the desired pressure.
I'm wondering if you are shimming the wrong valve. 130 psi is not all that bad although the "C" series did call for more pressure because they use the reserve pressure from the reverser to engage the steering clutches.
40 plus years working on JD 350s, 400Gs, 450s and other equipment both Ag and Construction.
Okay, You will have to forgive me sense I have slept several nights sense I last worked on one of these Valve bodies.
I went to my Manual for the 350C and you are in the right port for the engagement pressure and the right valve for adjustment.
My book shows a serial number break and there are differences in the pressures for each.
Maybe your manual has this information and if so again I apologize. If your machine is serial number 278391 or before then it should read 120 psi, plus or minus 10 psi.
If your machine is 278392 or after, then your pressure should be 150 psi, plus or minus 10 psi.
Have you established where your machine fits in this serial number break? If it is the earlier model then your pressure is right on. I'm not sure why your pressure is taking such a jump when you add shims, especially as high as you say it gets to. I have never had one go that high. But that doesn't mean that they can't.
I'm also curious if this machine is all original? Has the reverser or valve body been changed somewhere along the line? I'm curious what all you know about your crawler. That is, the history of all that may have been done to it over the years. This might help explain some things. Let us know what you know and we will go from there.
I went to my Manual for the 350C and you are in the right port for the engagement pressure and the right valve for adjustment.
My book shows a serial number break and there are differences in the pressures for each.
Maybe your manual has this information and if so again I apologize. If your machine is serial number 278391 or before then it should read 120 psi, plus or minus 10 psi.
If your machine is 278392 or after, then your pressure should be 150 psi, plus or minus 10 psi.
Have you established where your machine fits in this serial number break? If it is the earlier model then your pressure is right on. I'm not sure why your pressure is taking such a jump when you add shims, especially as high as you say it gets to. I have never had one go that high. But that doesn't mean that they can't.
I'm also curious if this machine is all original? Has the reverser or valve body been changed somewhere along the line? I'm curious what all you know about your crawler. That is, the history of all that may have been done to it over the years. This might help explain some things. Let us know what you know and we will go from there.
40 plus years working on JD 350s, 400Gs, 450s and other equipment both Ag and Construction.
Serial # is in the 150 psi range. Fairly late model machine of '85 vintage. Machine was a federal gov't unit so there were no modifications.
I dialed the pressure in to a perfect 150 psi. Let the machine warm up and started pushing and the pressures dropped way off. I ran the gauge the whole time. Machine reaches 50 psi and stops. When the divertor valve pedal is engaged and then disengaged pressures shoot back up to 90. However, once this happens the machine requires frequent pedal usage. Pressures remain in the 90-100 range. Obviously too low to allow proper engagement.
Any thoughts?
I dialed the pressure in to a perfect 150 psi. Let the machine warm up and started pushing and the pressures dropped way off. I ran the gauge the whole time. Machine reaches 50 psi and stops. When the divertor valve pedal is engaged and then disengaged pressures shoot back up to 90. However, once this happens the machine requires frequent pedal usage. Pressures remain in the 90-100 range. Obviously too low to allow proper engagement.
Any thoughts?
I have worked on several Federal machines here in MO and the biggest mistake I made was to assume they hadn't changed out something along the way. I'm not saying that yours is not pure, I'm just saying that the Feds are famous for "Contracting" out their repairs. Our State shop happened to be handy for them and we would help them out when we could.
I worked on one of there 350Ds once and assumed they hadn't had anything changed only to find that it had a 350C engine, a 3164 and it should have been a 3179 and the reverser had been swapped out of a 350B. All done by good repair shops but they didn't bother to mark the machine as having been changed. Only that repairs had been made. As far as the Feds were concerned, it was still a 350D.
I'm saying this for information purposes only! I'm not implying anything about the machine you have, I'm sure it is pure. So with that said lets move on...
One thing I would suspect is the accumulator piston may have a broken ring on it or it may have a scored bore. Usually when this happens your pressures tend to stay down all the time whether it is cold or hot. But it is still a possibility. Another issue is the adjustment bolt on the accumulator piston may be loose or completely out of the piston and allowing the pressures to fluctuate.
Another issue I've seen is the accumulator lever will be loose on the shaft. There is a pin that holds it in place on the shaft that will break or work its way out and cause the lever to move on the shaft. Thus throwing the accumulator out of the proper setting and your pressures will be up and down. If this is what is going on, you should be able to see it from the outside.
The clutch valve lever may also be worn or loose on its shaft. The valve itself could also be bad.
If you want to see if the clutch valve and lever, the accumulator piston and assembly is okay, you can remove the end cap off of the valve body. But be aware that it will be under spring tension that is quite strong and it will jump out at you when released. Remove all but two of the bolts holding it on and remove them slowly until it has released the tension. It may still jump a little when finally released.
Another possibility is the rate of shift screw and its orifice. I've seen this orifice get a piece of dirt in behind the the adjustment screw and cause your issue. This screw is located on the bottom of the valve body, front half, and is behind a 1/4" pipe plug. Take a small flat screw driver and remove the screw. You may have to work a small piece of wire or a torch cleaner up into the orifice to remove any dirt that may be in there. Usually there is enough oil flowing out of the orifice to remove any debris that may be there.
Your only other possibilities would be inside the reverser in one or more of the clutch pack piston seals or something inside the valve body. Either way you will have to remove the reverser to get at the internal parts.
The best I can say is good luck! I hope this helps and I also hope you can find the problem on the outside of the reverser.
I worked on one of there 350Ds once and assumed they hadn't had anything changed only to find that it had a 350C engine, a 3164 and it should have been a 3179 and the reverser had been swapped out of a 350B. All done by good repair shops but they didn't bother to mark the machine as having been changed. Only that repairs had been made. As far as the Feds were concerned, it was still a 350D.
I'm saying this for information purposes only! I'm not implying anything about the machine you have, I'm sure it is pure. So with that said lets move on...
One thing I would suspect is the accumulator piston may have a broken ring on it or it may have a scored bore. Usually when this happens your pressures tend to stay down all the time whether it is cold or hot. But it is still a possibility. Another issue is the adjustment bolt on the accumulator piston may be loose or completely out of the piston and allowing the pressures to fluctuate.
Another issue I've seen is the accumulator lever will be loose on the shaft. There is a pin that holds it in place on the shaft that will break or work its way out and cause the lever to move on the shaft. Thus throwing the accumulator out of the proper setting and your pressures will be up and down. If this is what is going on, you should be able to see it from the outside.
The clutch valve lever may also be worn or loose on its shaft. The valve itself could also be bad.
If you want to see if the clutch valve and lever, the accumulator piston and assembly is okay, you can remove the end cap off of the valve body. But be aware that it will be under spring tension that is quite strong and it will jump out at you when released. Remove all but two of the bolts holding it on and remove them slowly until it has released the tension. It may still jump a little when finally released.
Another possibility is the rate of shift screw and its orifice. I've seen this orifice get a piece of dirt in behind the the adjustment screw and cause your issue. This screw is located on the bottom of the valve body, front half, and is behind a 1/4" pipe plug. Take a small flat screw driver and remove the screw. You may have to work a small piece of wire or a torch cleaner up into the orifice to remove any dirt that may be in there. Usually there is enough oil flowing out of the orifice to remove any debris that may be there.
Your only other possibilities would be inside the reverser in one or more of the clutch pack piston seals or something inside the valve body. Either way you will have to remove the reverser to get at the internal parts.
The best I can say is good luck!
I hope this helps and I also hope you can find the problem on the outside of the reverser.40 plus years working on JD 350s, 400Gs, 450s and other equipment both Ag and Construction.
Sorry! I forgot to add something! 
You need to plug the pressure line leading to your steering clutches. This will eliminate the possibility of your steering clutches being the issue. You won't be able to move your machine but you will be able to see what your pressures are doing.
You can put your transmission in neutral and work the lever for your reverser, forward and reverse as well as working the clutch pedal to see what your clutch valve and accumulator are doing. If all is well with the reverser at this point, then your issue will be in one of the steering clutch packs.
You need to plug the pressure line leading to your steering clutches. This will eliminate the possibility of your steering clutches being the issue. You won't be able to move your machine but you will be able to see what your pressures are doing. You can put your transmission in neutral and work the lever for your reverser, forward and reverse as well as working the clutch pedal to see what your clutch valve and accumulator are doing. If all is well with the reverser at this point, then your issue will be in one of the steering clutch packs.
40 plus years working on JD 350s, 400Gs, 450s and other equipment both Ag and Construction.
Who is online
Users browsing this forum: No registered users and 287 guests