Good Afternoon everyone,,, Cat D5C hydro 7PS01136 . I would like to ask a couple questions about the blade joy stick control on this dozer. Whenever i get a "load" on the blade it will go in any direction it wants to go. The control is if it has no hyd pressure going to any function. A lot of times i can try to raise the blade and nothing happens then i can release the control and try again and the blade will work properly, this is true to all the blade functions. I do not know the history of this dozer but it has been this way since i have owned it. All fluids and filters have been replaced twice. I have not checked pump pressure because the blade will lift the dozer off the ground at idle speed after 10 hrs of use and will hold it that way for days . i just wanted to run this by the pros here before i start changing good working parts for new parts
I think some testing might be called for before firing the Parts Cannon. Do you mean the blade goes anywhere it wants to go or are you referring to the blade control handle in the cab.? If it is the control handle when the blade lift/lower function acts up does the blade tilt function continue to operate normally or does it behave the same as the lift function.?
That is correct the blade goes anywhere it wants. When it acts up its all functions,, and if i return the joystick to its neutral position and try to operate it again it may work normal
Time for some testing I think. You will need a well-damped pressure gauge that reads up to at least 3000, preferably 4000psi. See the illustration below of the implement hydraulic control valve. The pressure test tap is marked #3. The quick coupler that connects to it is a Cat P/N 6V-4143 (aftermarket alternatives are available). The quick coupler is threaded 1/8"-27 TPI NPT female in the other end. Connect the gauge to the test point and route it up to the cab located somewhere where the operator can easily see it. Run the machine and get it up to operating temperature, all the while keeping an eye on the gauge. When the blade function starts to act up what, if anything, happens to the gauge reading.?
ok i have the gauge, hose and fittings and will report the results ASAP
You could also check the relief pressure setting while you are at it. It is 2500 ± 50 psi with the oil at normal operating temperature and the blade cylinders in the fully raised position, engine at High Idle RPM, and the blade control lever in the RAISE position. Question: Have you changed a hydraulic filter yet.? If you haven't why not do so and cut the old one open to look for debris in the filter media.
Nige , good afternoon, sorry for the delay but here are my findings. The reading on the pressure gauge are as follows,readings are almost exactly the same hot or cold operation temp, sitting idle no operator input the gauge reads 0 psi , raise the blade all the way up and hold the control in up position gauge reads 1000 psi +/_ 100 psi then some type pressure relief opens and reading goes to 0 psi until i return joy stick to its center position , readings are similar with the other blade functions From my observation the blade is going any way it wants whenever i try to make adjustments and the relief valve opens. Part 2 cutting hyd filters open,,,, these filters only have about 100 hrs of use because i changed all the fluids when i got this machine and to my surprise they had absolutely no trash / metal / fiber ,,, they looked brand new. Now i can kinda understand the relief valve and pressure settings but why would the blade go any direction it wants ,,,, like if im trying to raise the blade the pressure goes to "0" why do the other cylinders even move at all.
I'm having a hard time figuring out how the cylinders just go any where they want if the spools are in the hold position the oil on both sides of the cylinder should be blocked. The only thing I think I would try first would be to remove panels by the hyd control spray them with lube work control around and try it again
This is way too low. The specification is 2500 ± 50 psi. I dunno what @pittsburgh cat man thinks but I would be tempted to remove the main relief valve and take a peek inside it as a first step. If you do this make careful note of the height of the adjustment screw #7 above the body of the vlave itself so that you can refit it with pretty much exactly the same adjustment as it was when you disassembled it.
My point is once the oil is on the cylinder side of valve and valves are in hold the main relief is out of the picture. However if it has line reliefs they are in the picture hard to grasp the line reliefs are all very low. I just had a thought If you tilt the blade can you raise the machine with lift cylinders and the tilt holds? Can you angle the blade push on the on the corner with the tractor will the blade stay angled ?
I did take the machine and raise the blade off the ground and put the corner of the blade against a tree,,,,i give it a good push and none of the cyl moved. I wondering if its me moving the control when things start to acting up. Im probly going to correct the relief pressure and then start from scratch and take better notes
That's why I suggested lubing the linkage. It might be hanging up and moving when it's not suppose to
Personally I would suggest you get everything apart under the joystick and lubricate the linkage first. Don't go adjusting any pressures until you know that the control linkage is all moving freely.
Ok , removed joystick cleaned all moving parts applied lube and all seems to be working except for the pressure setting. In post #6 the pic shows the pressure valve , the rod under the cap/nut looks to have a slot for a screw driver for making adjustments??? When i removed the cap/nut all i can see is a threaded rod with another nut that the rod is screwed into. Am i not seeing something how do i adjust this valve
Remove the cap put a screwdriver in the slot and hold loosen the nut on the screw about a 1/8 to a 1/4 turn turn screw in a small amount say a 1/4 of a turn tighten locknut check pressure if you need more repeat
Can you post a photo of the valve with the cap removed please.
yes sir , i will this may be a couple of days,,, i did not see a slot for a screwdriver but age has a way of making me look like a fool , i will report my findings ASAP
Some reliefs take a allen wrench
Hello everyone, i had some free time to check the pressure valve on my dozer , and im more confused now than i when i started ,,, i carefully removed the cap nut and turned the adjuster rod clockwise about 1/8 turn started the engine checked pressure ,,,no change ,, it pops off at 1000 psi,,,,,,repeated this several more times until the adjuster stopped moving freely. At this point i backed the rod to as close to my starting point checked again still the same 1000 psi . Looking at the valve assembly im almost postive that im adjusting the correct pressure valve. What are your thoughts ?
Did you check the pressure when cylinders are at end of stroke? did you check it with tilt and angle cylinders at end of stroke? when the cylinders are at end of stroke does it load the engine?
The first time when i was testing i did every function 1000 psi ,,,, this last time i only tried the blade up & down and there is a very slight load change on the engine this is at idle speed
How does it lift the tractor with the blade will it lift the front with no problem at idle?
Post a photo of the control valve assembly with an arrow pointing to the relief valve you are adjusting.
When you get the cylinder to the end of the stroke you should raise the engine RPM to High Idle.
This is what i have been adjusting
That is the main relief valve so you are correct. However the question remains why it doesn't have the scrdriver slot in the top end of the adjuster rod. Maybe it's time to remove that valve assembly completely and carefully disassemble it to see how it compares with the parts listing that I uploaded back in Post #9 on Page 1. It should be exactly identical. Also does raising the engine RPM to High Idle (max RPM in other words) when you stall the implement hydraulic system affect the measured pressures at all.?
Look at tag on relief should have part number and pressure
My bad ,,,, i forgot to add that bit of info it does have the slot for a screwdriver. And there was a metal band on the valve but i will have to remove it before i can read the tag
I missed a post , yes it will lift the dozer off the ground at idle or wot,, cold or hot. it will hold that position all day.
Some of the reliefs have a seal kit don't know about the one you have though If you tear the valve apart do not take the jam nut loose take the nut closest to valve body so you don't loose your adjustment
i think that im going to bring the machine back to my shop for better working environment for testing and repair. At this time i want to thank you Nige and Pittsburgh Cat Man , both of you have been very helpful and i appreciate everything. i want to get the machine closer so the next time you ask me to check something i can do so within 5 min instead of the two or three day delay.
9T-8959 is the listed seal kit for the 9T-7638 Relief Valve As. My vote goes to disassembling the valve and checking it against the parts list to ensure that it is assembled correctly and that all the internal parts that should be there are actually there and in the correct places. Unfortunately I cannot find a Part Number or a Specification for the spring that is inside it.
just wanted to let everyone know ,,,,i took the pressure relief valve apart and it was a total train wreck,,,, new service kit from Cat will be in hand within 24 hrs ,,,,,i will report my results ASAP
update,,,, Service Kit 9T-8959 installed and everything works perfect ,,set pressure at 2250psi ,,hyd are strong and fast acting ,,,,,,what a difference
Glad you finally solved the problem, and hopefully the seal kit didn't break the bank. It did seem somewhat strange that attempting to adjust the main relief pressure setting had absolutely no effect. Now you know why.