96 Blazer no reverse

Hello All,

Awhile back i put a used transmission into my blazer. The guy told me that it only had about 40,000 miles on it. After putting the transmission in everything appeared to be running well. A few days later I went to back up only to find that there was no reverse. My first thought was sungear because I had the same problem once on the original transmission. I knew that a broken sungear caused a loss of R,2,4. I took it down the road and it is still shifting through all of the gears correctly without any noises or shutters. When i put the vehicle in reverse it shutter like it is trying to engage reverse. It moves a little but no measureable amount. I checked the fluid and it was pretty low. After topping of the fluid the problem still persisted. With no evidence of a broken sungear I have no clue what the problem could be. Any help with the diagnosis would be great.

Double check the fluid level good and hot in park with engine running.
Pull pan and see what is in the bottom of pan and in filter.
Make sure filter and and flter seal is good and right fillter.
Reverse is all internal mechanical.
If no backup the transmission has to come out.
Got any warranty on it?
If you ran it low on fluid you fried the clutches.
Where is it leaking?

If i take the pan off what am I looking for?
Also...would fried clutch plates be the cause for no reverse or is it the sun gear. I ruled out the sungear since I still have 2nd and 4th gear but I could be wrong.

Look for Metal or clutch shavings and ground up grit.
Check filter and filter seal and right filter to.
No reverse and ran low on fluid points to fried clutches.
MT

Thanks for the help. Me and my dad took the transmission out and brought it to a shop to have it fixed. Turns out the guy I bought it from had allowed water get in the tranny. This ruined some paper seals on some of the clutch plates. So your diagnosis was spot on. It was the low reverse clutch plates. He found several other problems while in the tranny. So I spent one day taking it out and was able to get it fixed for 290 dollars with a one year warranty on the work he did. I do have one question though. Is there a specific procedure for filling the tranny with fluid once i put it back in the truck. I wasnt happy with the way it went last time. Any suggestions would be awesome. Thanks.

You are welcome and thanks for posting back how it went and the fix.
I would flush the transmission coolers and lines.
Before hooking them up to transmission.
May be water or trash in the coolers.
To fill up.
Add 5-6 qts before start up.
Start in up for 30 seconds to a minute in park and shut off engine and add about 3 more qts.
Then start up and check fluid level on dip stick.
Fill it up to add level running.
And run it threw gears and recheck fluid level.
Hold it around add level or lower crosshatch on dip stick.
Then get it good and warm/hot and recheck fluid level with engine running in park hot.
Good Luck
MT

Have you figured out how the water got in it?
Does it have the flip top dip stick?
Good luck.

Thanks for the fill procedure. As for the water in the tranny....the guy I bought it from had left it sitting empty for awhile without telling me. I am assuming condensation had built up over that time. The guy at the shop even told me there was some rust inside the tranny. Any tips for draining the coolant for the tranny like you suggested. I hope that doesnt mean taking the whole radiator out. Is there a drain plug for the transmission portion like there is for the engine coolant? Thanks ahead of time.

If transmission has been repaired it will be ok.
What you need to clean is the rad cooler and transmission external cooler if it has one.
They make cooler flush kits.
Ask the parts place or transmission shop for one.
I use cleaning solvent with air pressure to clean them.
Or you can remove rad and take it to a rad shop and have the cooler cleaned.

A transmission sitting should not get much water in it unless left under a leaking roof and opened up but will rust up if not oiled good.
Good Luck
MT