tranny slipping
 

got a 96 4x4 2dr 4.3 v6 came out of a 97 zr2 blazer everything fit bolted and went in perfect drove it for about 6 months checked fluids daily i was driving down the road one day and when i am down below 30mph in overdrive the tranny slips so basically i have to take off in 2nd till i get to 35ish then i shift to od and it doesn't slip but won't shift into drive or whatever gears are after 2nd i changed fluid and filter (the old had no shavings looked clean and good and no burnt smell) so i have no clue what it is 4x4 don't work either i'm thinking it is a sensor or a vaccuum came off ( i had a vaccuum melted to the exhaust ) so i am thinking that is it but if not it's the sensor or both i hate to take to a tranny shop and have the whole thing rebuilt if it's something an average joe with some mechanical skill could conquer but figured i would ask here first thanks in advance

There really isn't much in common between the transmission and the transfer case. There are no vacuum controlled components in the transmission.

So what gears are slipping? Just 4th (OD)? Does it act like it is in neutral and just rev or can you feel it pull a bit?

ok i can take off in od or d or even 2nd and 1st. but if i take off in od as soon as i hit about 30-35 it slips now if i lightly give it gas sometimes it doesn't slip same with D but 2nd and 1st never slip as far as the vaccuum i was talking about i think that is for my 4x4 and that is what is causing it not to work.

So what gear are you in when it slips? It should start out in first, shift to second, then shift to third, etc. The speed/rpm which these shifts occur depends on throttle position so listing a speed without a reference to a gear is not helpful in determining which gear is slipping. Is it slipping on the 2-3 shift? Seems to make sense because it would never get to 3rd if you had the shifter in 2nd or 1st.

it slips while going into 3rd, 1st and second pulls and drives good it's when it goes or about to into 3rd (but only does it when in drive and overdrive before 35 mph) after that it's reving high so i think it's still in second and never goes past that

From the tech article thread:
4L60E Information & Common Problems - Compilation

A "No 2-3 Shift or 2-3 Shift Slips, Rough, or Hunting" condition could be caused by any one of the items noted in the attachment. Some of the items can be checked by either pulling the valve body or the 2-4 servo assembly.

so basically i am gonna have to pull the tranny and dig in? if so i will just take to a shop so this time it's done right.... already pull engine and tranny once cause of the blowed engine then second time the tranny that came with the engine completely went out like it's always in park/neuteral and yeah don't feel like it again.... but i wanna thank you very much your really knowledged on blazers

Some things can be checked without pulling the transmission completely out. But if the 3-4 clutch pack is gone, then yeah, a rebuild is in order.

Mine is getting gone through Monday... The check ball capsule to the 2-4 Servo(Corvette servo is in mine)was leaking back in the clutches. First sign was the fact that when it was started it would lunge forward a bit. Burned up the 3-4 clutches.

Recipe is as follows:

Corvette servo, High Energy-Carbon/Kevlar Clutches and Band, All new seals and gaskets, Beast sun shell, Orange Box kit from transgo, Pinless accumulators with teflon seals, and a few other tricks. The guy is a former NHRA track champion and only does truck trannies.

my jimmy is doing the exact same thing.. wont go into 3rd or 4th. worst thing is that ive been trying to sell it all week and now this happens. i was asking 2200 for my jimmy should i just list it at 1400$ and say f**k it?