Hello all, I'm having an issue with a D4H LGP III s/n 9GJ. When the machine is first started and the trans is not up to operating temp, the brakes seem to drag at first. Usually a few pumps on the pedal can get them to free up but it can't be good for the machine. Also the trans warning light has been coming on. I have changed the filter and it made no difference. This issue I have found good info on here so I plan to check the 9X7781 trans pressure switch and also check the trans pickup strainer. Not sure if these problems are related but thought I should include all the symptoms it has. Thanks in advance for any help.
I'm not familiar with the internals of your specific machine but I know the general principles and I'd suggest that you need to take a step back, then proceed very carefully. The brakes on a dozer have very limited interconnection, generally a problem on one side doesn't automatically mean a problem on the other side. Combine this with a transmission (there's only one of these!) warning light and a potentially nasty picture emerges. I'd be figuring out what's going on before I moved this machine. It might be harmless, but if it isn't...? Sorry I can't help more, I'm only replying because after two days no-one else has. Like I say, I don't know the machine but I sure as heck know the precursors of expensive repairs! Stop, think!
im not a dozer mechanic(so my comments might not be productive).....but i also have a D4H III so its good to hear others issues and fixes(on a similar machine).....mine has never had any form of brake dragging issue but it does need to warm up a bit (fluids) before engaging the transmission, if i jump on it start it and go with the fluids cold it will respond slowly till the fluids warm up. So i would try starting it letting it run a bit to warm up and still see if you have the issue, also a transmission warning light would indicate low pressure or low fluids or both, so i would check the pick up strainer etc as you indicate, how many HRs is on your machine?
brakes are spring applied pressure release, adjust the trans lock-out rod it may be warn enough to not allow lever to release the valve all of the way. then check trans pressures i can't remember which one P 1,2 or is brake pressure but it is not difficult...i could get you more info once you get a gauge and hose to connect to the test port inside where the battery disconnect is or on the back of the trans depending....as far as the trans bypass oil light comming on not a big issue if it is not a new problem,,there are at least 3 different trans filters for this machine you may have gotten the wrong one, some tractors with an ambient of 50 degrees ferenheit or less will make the oil bypass light come on under normal operating conditions until operating temp is reached. you are suspecting low trans pressure without gauge, pull floor pan under your feet, pull into first forward high idle ,does driveline stop spinning? oh yeah foot on brake pedal so it does'nt move...if it drives through foot pedal brake try second gear...