Transmission not shifting into higher gears

I have a 1992 GMC Jimmy, four door, 4.3L V6 CPI with 140,000 KMs.

Just yesterday night when in drive or Overdrive as soon as the transmission reaches its shift point to 3rd gear at about 36Km/h there becomes no power to the drive train, just engine revs with no load.

The trans fluid had be flushed two years ago with synthetic, and now the fluid is darker red with a burnt smell. I had a mechanic take it for a test drive and he determined that the 3/4 gear clutch pack had worn out.

He tells me that I need to get a transmission overhaul or a working tranny installed to fix this problem!

Are there no simple solutions to this problem such as a shift solenoid or vacuum leak !!!

thanks for the input.:(

Welcome to AF.
Is reverse working good?
Will it shift if you manual shift it low to 2 and 2-3 and 3-4?
What transmission does it have?
Has the pan been droped and filter checked?
How much stuff in bottom of pan?

Reverse works good
It will only use 1st and 2nd gears manual or automatic
Trans type: 700r4
I did not think it was worth dropping b/c if what the mechanic told me is correct then I should find clutch pack material and metal filling.

I found this:
Automatic transmission: TH-700-R4 automatic transmissions may shift late or not upshift at all. The problem is a stuck throttle valve inside the transmission.
(1990-94)

Dropping the pan will tell you a lot about transmission condition.
Yes check the valve amd cabel both.
Can you feel a double tension when you pull the TB cabel.
Also a stuck valve or striped gear on governor will mess up shifting.
MT

I'm 'think' I'm just about to drop the pan to take a look.

I was reading the paper and someone is selling a 700r4.

It's off a 1986 3/4 ton 6.2 L diesel w/ no four wheel drive. It does have OD.

Are these 700r4 Auto transmissions compatible all around or were there "changes made in 1988"?

thanks

I would drop the pan and check your transmission out before throwing another transmission at it.
Might be a simple fix.
Is your jimmy a 2 or 4 W?
2W and 4W are different rear tail out put shafts.
The 86 is a long way from a 92
Lot of internal bigger changes.
Converters are 6 bolt on the 6.5
6.2 diesel transmissions are a long way from a 4.3 v6
The lockup wiring would have to be changed over.

If you are going to get another transmission make sure it is a good on and one that will fit and work.

it's 4 wheel drive. So i managed to drop the pan, and to my surprise no chunks were found only gray metal dust about a table spoons worth or 2! More then i remember seeing from the last change.

I can feel a double tension when I pull the TV cable.

Other then the dark/burnt fluid and fine metal dust it looked good. Threw it back together with new filter + fluid and nothing has changed.

I think I notice 2nd gear starting to feel/sound a little rougher.

So I'm not sure but i think i need a reman!

it's 4 wheel drive. So i managed to drop the pan, and to my surprise no chunks were found only gray metal dust about a table spoons worth or 2! More then i remember seeing from the last change.

I can feel a double tension when I pull the TV cable.

Other then the dark/burnt fluid and fine metal dust it looked good. Threw it back together with new filter + fluid and nothing has changed.

I think I notice 2nd gear starting to feel/sound a little rougher.

So I'm not sure but i think i need a reman!

Before you give up on it have a look at the governor.
Check the governor valve plunger and plastic gear.
Good Luck
MT