Good day everyone, hoping someone here might have an idea whats going on with my Cat. ONce the machine warms up the trans pressure will drop to around 150 psi as soon as the rpms pass 1350-1360 and will not return to normal pressure until engine rpm drops to 1299. I thought maybe I had a leaking brake, but i have kinda ruled that out. It does this in all gears including neutral, i have check the filter and didnt see anything of concern and i am going to check the screen this afternoon. Could this be a speed sensor telling the ecm to drop trans pressure or a faulty selenoid? Trans pump has good pressure 400psi plus until it starts to act up I called the local Finning field Mechanic, so am waiting for a return call to setup a time for him to diagnose but in the meantime if anyone has an idea i would like to hear it thankyou.
I believe your problem is electrical, I experienced a similar problem on an early ECM controlled trans in a 980. It was an alternator that had a bad regulator and was charging too high of voltage. Replacing the alt corrected this problem. A speed sensor could also be a problem, not the sensor it's self but the gear teeth it's counting. Damaged teeth, as little as 0.050" shaved off the top of a starter ring's gear teeth can send glitches to the computer. May need a scope meter to find this. Later Bob
996r the D6R machines have a priority valve solenoid that is controlled by the ECM on the machine, one of the things that does control the priority valve is rpms. when rpms are under around 1250 or so the machine is in priority mode and the pump pressure is increased by combining two sections of the trans. pump together. reason is to provide more oil flow when at lower rpms. and when making a trans. shift to prevent the pressure from dropping low enough that the spring applied brakes will try to set momentaily and make the macine shudder. things that affect the on/off of the priority valve are rpms, oil temp, and trans. shifting. where are you checking the pump pressure at ?
I took the pump pressure at the transmission filter housing, and also at the brake valves under the seat. is the priority valve solenoid on the left side of machine sorta down by stump pan? So maybe the ecm is getting a screwy signal and then opening the valve causing low pressure and brakes to come on. Thankyou kbeen and Bob
I will look for a schematic and see if the oil flow that's switched in is torque inlet oil, if so and your machine is working good there may be nothing wrong. If you have an oil leakage problem in a transmission it's accompanied by overheating, if you have no overheating while working all day long things will be good. Later Bob
it was working fine the day before, next morning i went about 10 ft and new something was up. No overheating issues, so i'm thinking its some kind of little hiccup.
ok if i understand correctly, low oil temp, low rpms and trans shifting will put the valve in priority mode which diverts oil flow from the torque and lube systems to the trans/brake system. Once temperature and rpms come up the valve will close, and transmission will be solely on the transmission charging circut of the powertrain pump. So if this is the case then my low oil pressure at higher rpms once oil is warm will be due to a leak in the transmission/brakes, blockage or faulty pump. hmmmm now what?
Quite likely but I must look at a schematic to confirm that. Later Bob
There is an H shaped manifold at the outlet of the trans pump sections. It contains a check valve that allows the oil from the priority valve to enter and join the flow from the trans pump. If this check valve doesn't close the trans oil can escape into the flow of oil to the torque and lube, thus your 150 psi(torque inlet pressure) at the filter when the priority solenoid is not on at higher engine speeds. Later Bob
Hi Bob, Had this pic on file from another post.....sounds like you are referring to the valve in cross section C-C. Item 51 is the valve.
Thanks OM, that's the manifold and valve I was referring to. Later Bob
Haven't gotta chance to check it out yet, but I'm thinking that valve is the culprit. Really appreciate help Bob, will update in a couple of days when I dig into it
well had a good look at the check valve seems to be in good shape, was holding oil on the correct side....maybe i just have a weak pump, gonna keep looking for leaks
Was it moving free in body? Later Bob
yep moved good, and the spring was not broken, o ring look good.
Well I thought that was the one in the schematic, looked like it to me. Try it again once you get it back together. I don't think the extra flow the priority valve adds could bring up the pressure if there was a problem with the main relief but you never know. Later Bob
think i identified the problem, leaking modulation valve as there is a lot of oil flowing of the trans hydraulic control valve assembly.
Something breaking open would give you that instant problem you have. Was it a very cold morning you first noticed the problem? Later Bob
nope not modulation valve, anyone no if its normal for oil to be pouring of of the the manifold that the modulation valves are bolted to?
short answer to my question ....yes
Got her fixed, ended up being a stuck transmission relief valve. Thanks for all the help guys
Thanks for letting us know. Was that the modulating relief valve? Later Bob
Yeah, the relief valve is in the manifold that the modulation valves are bolted on.
Good day I'm a new member Got a problem on D6R transmission electric but we put a 3306 in it start up good all gear shitf good went and test it 45minutes in 1st gear forward gone and came back strong and good then forward gone only reverse 2de and 3 Stop switch off start 1st forward and reverse good 2de forward good reverse gone forward 3de good reverse gone Now we have forward all shift good no reverse pressure look good but no movement in reverse Can you help no ET laptop
Serial Number would be a good start. There must be 50+ different models of D6R. Take a look at the RH top corner of the digital window that shows the hourmeter. After you turn the key on and the panel completes the self-test do the words "SERV CODE" stay lit.?
By the sound of things the valve found to be faulty in the original post was the modulation control valve that is bolted just near the drive coupling on the outside of the transmission, standard voltage is sent to a mag coil at a set engine speed/temp, the coils that work the speed and direction on the R use pulse width modulation the same as the first section of the brakes. tctractors
I'll get it later today not on site now but will have a look and let you know the dach is off can not see code
That being the case the Serial Number on its own is worthless. By the sounds of your description of the problem, which I must admit I don't totally understand, it sounds to me like it is likely to be related to the electrical/electronic system. Therefore the first logical place to start is Diagnostic Codes. You are either going to have to fix the Monitor Panel so you can see the Codes or get a laptop with ET. I don't see any other options.
Hi, i think i have the same problem, can you tell me were is this relief valve? I check the pressures on the gear, sims to be ok, i think i have not the brake release pressure. Ty
Make sure there is no leak in the transmission. My personal vehicle is currently having a similar issue and it ended up being an oil leak from the oil cooler
Try starting a new thread. Quote your machine model and Serial Number. Give a complete description of what symptoms you have now and what the machine was doing leading up to the problem appearing. We can always refer back to this thread if necessary.
Did you ever figure it out ?