Hey everyone i have an 87d3b SN 23Y02385 Does the transmission fluid operate the steering or is it from the bevel gear? My bevel gear fluid was high and i was having intermittent steering issues i changed the fluid and it seemed to help the fluid is now high on the dipstick and steering acting up again seems like on start up it steers fine but once i cat around for a while it slowly starts to act up. As i have been reading onto this issue i have read the fluid to operate the steering comes from the transmission. I had to extract the slave cylinder plug because they were broken off i plan to pressure test the system soon. Any info will help! Thanks!!
Transmission fluid is used for the steering clutches and steering valves under the seat. You could have a leak letting fluid in the bevel gear if you have wet brakes but it wouldn't be trans. fluid. First thing to check with steering issues is the steering clutch valves under the seat. The rollers can get flat spots not allowing full travel and the valves or hoses could spring a leak. I had one start leaking. I took it to a shop and they sent the spool out to get rechromed and they honed the bore to fit. The slave cylinders/fittings could also develop a leak. That said, from you describe it as being intermittent, I'd look at the rollers on the steering valves. Flat spots could cause the steering to work better some times. The rollers need to be pressed out and new ones pressed on. Generally done at a Cat dealer or independent shop. When everything is working properly it should only require light pressure on the pedals to steer. There is a simpler way to adjust the brakes than what it says in the Cat manual. I've posted it in the past but could again if you'd like.
I rebuilt the steering control valve for the left side that didn’t seem to make much difference. The all the parts were definitely on their last leg including the roller, i still need to rebuild the other side. The strange thing about what i have going on is upon startup the steering is flawless sharp turns. If im spreading a pile of material out it works great for 20 minutes than starts to get weak. If im catting around alot the issue seems to develop faster. If i shut the machine off and let it sit for a while the cycle starts over.
What oil is in the trans.? Checking pressure is the next step and if it's within spec. and nothings leaking your steering clutches could need to be rebuilt.
Im sure of what oil is currently in the transmission. I just recently bought it in the spring. I plan to swap it out with TDTO 30W. Thinking it might not hurt to try to bleed the fluid out of the slave cylinder ports to make sure fresh fluid gets through every part of the System then pressure test. Not sure if the bleeding is a a waste of time or not? Hopefully its not the steering clutch’s if it is looks like a decent winter project!
I've had the engine and trans. out 3 times and never needed to bleed the steering clutches. I also didn't need to when I had the valve under the seat rebuilt or even when the steering clutches were pulled out and rebuilt. Slave cylinders weren't leaking so I didn't need to do anything with them but did remove them when I pulled the steering clutches. Never had to bleed anything.
Mine had some issues, replacing the steering valve fixed it. One valve was replaced when I bought the dozer, then later after pulling clutches and finding nothing wrong I replaced the other valve
I think I will definitely look to replacing other valve before i get into the clutch's. I don’t feel like there is any slipping going on when pushing dirt. Hoping to not have to replace the clutch's.
The steering clutches don't really affect pushing straight ahead.
Hmm, that’s good to know. I figured that you would get some slipping while pushing under load. I have alot to learn about these old machines still.
Try this, start pushing underload and step in on each pedal about 1/3 travel. That side should stop turning but brake will not be applied.
When I first start it up and start running it, It turns with the slightest amount of pressure on either pedal, even under load. After pushing and moving and turning for a while it gets weaker and stops working unless i slam on the pedal witch is when i stop running it because i know its not right.
First 1/3 of travel should disengage clutch, full pedal applies brake. Sure sounds it's the pedal valve. I have a thread where I replaced it, will look for it
Pedal travel could be up half way down. It depends on how the pedals are adjusted. Driving with no load pushing both pedals part way down should stop the machine. That tells you the steering clutches are disengaging.