I hope I am putting this in the right place. I don't know the type of transmission I have. It is automatic, stock for an 83 6.2 Chevy Suburban 2500.

Driving down the road today, I felt a ‘clunk.” It felt like I ran over a board in the road, but nothing was there. Then I noticed my truck was not shifting to next gear. I drove home at 10 mph.

I baby my old truck and have never had a transmission problem. The fluid looks ok.

What should I do? Is this bad?

Thanks for any advice

Look under the truck at the trans pan and describe it to me. Square or rectangular with pointed tail. Does it have a vacum modulator on passenger side ( small round canister above pan with a hose). I will help you diagnose it.
mike

My guess is a turbo 400 being a 3/4 ton..

I guessing a TH400 as well. isnt it easier to just look at the shift column as see if its says D-2-1 or O/D-3-2-1?

Thanks for the quick reply. I will look in the morning, but I know the pan is rectangular, and I know it is not Turbo anything.

I’m 99% sure my tranny is called 700R4. I looked it up in my Chiltons and 83 was the first year those were installed, and I do recall hearing that before.

I said the pan was rectangular, it may be closer to a square. Kind of hard to tell. No tail though.

My column says (123D) the words “overdrive” written on top.

Mike L, I do see a round thing above the pan, about the size of a filled in doughnut. I didn’t notice a hose.

I hate being a clueless dame, but in all my years of driving, I’ve never had to deal with a transmission problem

Edited to clarify model is a Silverado 20, in case it matters.

The early 700R4's were known to have some major downfalls to them. The only easy checks that I can think of is to make sure that the kickdown cable isn't jammed, and that the gearshift is clicking through the detents. I'm not a tranny guy or nothing but I know that up until around the late 80's the 700R had quite a few problems in the trucks.

guess we were wrong, sounds like a 700R4 in it.

Mike is the man for the info. first thing Id check is fluid level.

Now that we are sure it's a 700 this is what you do first. Find the throttle pressure cable coming from the trans; it will be secured in a steel bracket with wire exposed in the engine valley near firewall. Strum the cable like a banjo about 5 or six times ( this might unstick throttle valve if it is sticking) If that don't work check the governor. Left side of trans towards the rear you will find a steel cover pressed into tran.( Sometimes there is a clip to remove) Carefully with hammer and blunt screw driver tap it out of case gently, have a bucket there. You will find the governor in the case which can be removed by pulling it out. Look at the plastic gear on the end and see if it is good. If the gear is good you are probably in for a trans o/h. If the gear is bad, have your local trans shop install a new gear. You do not need a new governor, only the gear. Hope this helps. If you need more info my # is in sig.
mike

Looks like I have to read the Chilton manual to try and figure out what you are talking about. That may take a while.

Can you speculate what the “clunk or thump” I described in first post, might be? Could something have just busted?

Thanks for taking the time to answer me.

Clunk could be the governor gear stripping and causing a downshift. If thats not it, you are in trouble my friend. If you call me, I can save you time as far as trying to read the chilton.

I am having the exact same problem. 700R4 This tranny has been nothing but trouble. Front seal blown, then leaks, now shifting issues. I can get it to shift from 1st to 2nd By reving the enginein nutral then dropping it into drive. Then i acts like it just starts out in second then shifts fine into 3rd. I never feel it shift into overdrive, but it seems to do fine after that. I am concidering a swap to a 400, but need this to get me by for a few months while i gather the parts.

The 700R4 is junk, only good thing about it is the fact it has an overdrive gear, a much heavier duty transmission would be a TH350 or TH400. 700R4's can also be made to last if they are built up correctly by a reputable transmission shop.

The 700R4 is junk, only good thing about it is the fact it has an overdrive gear, a much heavier duty transmission would be a TH350 or TH400. 700R4's can also be made to last if they are built up correctly by a reputable transmission shop.

The 700 gets a bad rap because there are too many idiots trying to fix them and don't know what they are doing. My shop was a GM warranty station from '82 to '99. I did the first 700 in CA. I was able to diagnose it thanks to the help of Steve Younger at Transgo. He was on top of this trans before any GM tech was. The 700 trans is a 350 with an overdrive. I love these old wives tales. The 400 trans is very strong, but if you let the same guys build it that screwed up your 700, it won't last any longer. Garbage in, Garbage out.
mike

( Mike L I hope you see this post)

Update on tranny problem

Mike L you are The Man!!!

I am so grateful for your help.

I finally got the governor out and the gear looked ok. I could not find the throttle cable to strum, and after talking to several tranny guys, one felt pity for me and took a look at it today. He pushed a button behind the air cleaner to shorten the cable a bit. We took it for a ride and it shifted….Woohoo!.

He told me to get a bottle of Lugas which I will do Mon. He said it shifted just a bit late. He called it “stacked.” He said to run the Lugas a few days and let him know how it was. If it still wasn’t right, he would put a new governor in. Something about the weights and looking through the thing. He lost me there.

Anyway, he was a nice old guy that had knowledge of the 700r4. Like you, he said they are not junky transmissions and mine should be ok.

Now I can go back to trying to solve the problems I had before this stuck throttle thingy showed up.

I tried calling you several times, but could never get through. You must keep very busy.
Once again, thank you..thank you..thank you.!

"" i know it's not a turbo anything"" Allmost all GM transmissions are called "turbo". It's short for turbo hydramatic. Has nothing to do with the turbo on the eng.