Shift 76 chev

[Oldsoul79]

Hey everybody.  New to the group. I have a 1976 silverado 20 with auto transmission 4x4.  This is my ranch truck for doing chores and stuff. Not too long ago I would have to hive it lots of gas when in reverse to go. Now it will not go anywhere in reverse.  Drive,1 and 2 are great. Any ideas and how her is the fix?
I'm good with stuff but struggle with vehicle mechanics.

[VileZambonie]

Check the fluid level first....

[Oldsoul79]

I checked it and it was good. Thanks

[Captkaos]

original trans, is the fluid discolored or smell burnt?

[JohnnyPopper]

You didn't mention 3rd gear. Does it slip too?

Do you hear a whine coming from the trans when at operating temp?

If yes and fluid is brown/burnt, possible your filter is clogged.

Or your internal seals are bad. Cheap fix is trans sealer, but if you haven't serviced the trans in a while do that first. New filter and oil.

[JohnnyPopper]

You didn't mention 3rd gear. Does it slip too?

Do you hear a whine coming from the trans when at operating temp?

If yes and fluid is brown/burnt, possible your filter is clogged.

Or your internal seals are bad. Cheap fix is trans sealer, but if you haven't serviced the trans in a while do this first... New filter and oil.

[Oldsoul79]

All gears work but reverse. I changed the fluid and filter over the weekend.  There was a little crud in bottom of pan but minimal. Still no reverse

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[VileZambonie]

Did you look at the manual valve when you had the pan down?

[Oldsoul79]

Not sure what the manual valve is

[VileZambonie]

You are checking the fluid level with the engine running right?

The manual valve is what controls the gear range based on the gear selector position. When you drop the pan, you can see the shift shaft, detent spring and a rod that engages the parking pawl. Look at the S shaped link that connects the linkage to the manual valve. Make sure you have the wheels chocked while you are under there and parking brake set. Have an assistant move the shifter through each detent and look to see if anything is loose or broken, etc