MF400 dozer

Anton van der Merwe · Sep 27, 2014

Hi there. I own a mf400 dozer. I rebuilt it after I bought it a year ago and only started using it about a month ago for short periods because it was still winter here. spring has come and we average 32-37'C at day time.

The transmission temperature rises to 110'C after 2hours of working. It is a concern to me and that's why I am asking for help. While repairing it I found that the transmission strainer was badly blocked. I cleaned it properly and added new atf transmission fluid and a filter. If the transmission gets that hot the turning of the machine is also difficult.

I do understand that the pumps may have wear on them but will thicker oil do the trick? The oil that came out of it was thicker and brown of color. As the transmission temperature rises it also picks up my engine temperature rapidly because of the oil cooler from the transmission running through the bottom of the radiator tank. I'm sure these machines are made to run longer than 2hours a day?

If anyone can help me with any suggestions please help me.
thanks

AJ. · Sep 28, 2014

I'm well rusty on MF machinery as it was never that popular,I think the 400 power train was a torque converter,hydraulic shuttle with two speeds,is your radiator clean inside and out,can you check the pressures,it sounds by what you say that there is not enough pressure when it heats up,originally nearly all hydraulic shuttles used ATF,that recommended fluid is now changed to HyTrans oil and it is a bit thicker but the main reason is the additives in it that reduce clutch disc wear,low pump pressure will not engage the shuttle clutch properly and should it slip that would causes heat it also accounts for the poor steering,a pressure check should establish if it the pump or a leaking regulator valve.
AJ

Anton van der Merwe · Sep 29, 2014

Yes the powertrain consists of a torque converter, forward and reverse transmission. Then a small 2speed gearbox joint on the diff(high and low). The 2 boxes are joint with a small propshaft. The radiator was opened and cleaned when I overhauled the engine. If I start it up for the first time on a day then steering and pulling is very good with low rpm's, when hot steering is poor and the machine is able to spin both tracks on full rpm's when approaching a tree wrong. The machine has a torque converter pump and another pump for the steering clutches and brake system but it all works from the transmission oil and runs on the torque converter outer housing. No work was done on the transmission. I only cleaned the strainer and drained the oil and added fresh oil and filter. oil color still red.

AJ. · Sep 29, 2014

With the machine pushing good it rules out the torque,shuttle and pump,or any heat coming from the shuttle,seeing you have a steering problem the steering pump may be the cause of your trouble,it is typical of a gear type pump to make pressure when the oil is cold and lose it when it heats up,the gears wear the figure eight in the end plates,I have had them machined flat with some success,I think you should have it off and have a look at it.
Good luck
AJ

Anton van der Merwe · Sep 30, 2014

Great analysis. Never thought of the brake pump. I'll have a look this weekend and report back. thanks a lot AJ.

Anton van der Merwe · Oct 9, 2014

I opened up the 2x pumps and they both show signs of scorch marks on the outside casing where the teeth mesh in each other to create the pressure. Looks like they ran without oil for a while with the previous owner. Will bolt them back together and install them to do pressure checks on the torque converter pump and on the steering clutches and brakes.

MF400 dozer

Anton van der Merwe

New User

AJ.

Well-known Member

Anton van der Merwe

New User

AJ.

Well-known Member

Anton van der Merwe

New User

Anton van der Merwe

New User

Similar threads