I have a 55 f600 farm truck and am having trouble with the rear end staying in gear. It just pops out of gear usually happens during coasting.It sounds like maybe the selenium maybe cycling. It seems to work fine for a few miles and then acts up. Any thoughts?

 

I'm guessing you mean it is popping out of high. There can be a few different causes, I would look at the vacuum system first, particularly because it is an issue when coasting.

 

Thanks or the response, I think mine is electric but I will double check.

 

Okay, I said vacuum because my F6 is vacuum actuated. Check that the electrical actuated system is up to par. If it is all in primo shape, the next step is to look inside the dif cover.

 

By 1955 they are all electric. Willing to bet it is not fully engaged in high
usually caused by a dirty or rusty worm screw in the unit. You should first
pop the aluminum cover and examine it (dont shift it while the cover is off).
This cover also serves as a pivot support. Or take the whole unit off
for a bench test. two bolts remove wires and its off. dont worry theres no
wild monsters in there.

 

Big job - you have me curious now because I was just getting ready to tear into the rear axle on my truck. Why don't you want to shift it when the aluminum cover is off? Takes.

 

Hi, because the alum cover is also a bearing support-when off you will
see what I mean. as I said over time moisture will form rust on the
worm and bottom ball bearing causing it to be sluggish or just not being
free. With a good cleaning & oil should be good to go. Also in there is
a reversing switch that switches motor direction (high/low) Napa has
that. Good time to replace. Napa also has electric motor and the red
shift button. (or they will get it from warehouse)

sam

 

Sam, your in depth, real world knowledge of this old stuff, how it works, what is probably wrong with it, and how to fix it is amazing. What a valuable source of information you are.
Thanks for your many contributions