Transmission Slip Question??

[mijon]

Problem:

The tranny on my M-1008 seems to be slipping going into the 3rd gear. Shifts into second gear fine. But has a hard time shifting into 3rd most of the time. The problem seems to be the worst when I have the front locked out, in 4 wheel drive. In two wheel drive the truck shifts more smoothly, but there still seems to be some issues. In 4 wheel drive the truck shifts into third fine sometimes and other times only after about a quarter mile idling around 33 before it will shift.

Question:

Any suggestions as to what the problem is? Tranny Fluid is not burning and filled all the way up on the dipstick. I have never changed the tranny filter though. Any advice would be great (opinions, TM's, etc.) Need a place to start looking around a little myself, before I take it anywhere and start spending $$ that I don't have right now.
Thanks,

 

[dependable]

A great place to start would be changing the tranny filter. It is probably original, and if you are lucky, it might help your problem. Otherwise, check out the vacuum system, lots of threads on that.

 

[MarcusOReallyus]

A second vote for chanign the filter, and check out your vacuum lines. If the lines are leaking, your shifting will not be happy. The good news is, it's a dirt cheap and easy fix. I mean under $20 dirt cheap. There's also the vacuum pump and modulator. Make sure these are okay before you shell out bucks for a rebuild.

If all of that is good, here's another option before you spend the big bucks.