I've got one hell of a problem

[Mahlon Osterhout]

I was out running the truck today and I lost my gears... I was going up a small incline today on my trail and all of a sudden my rpms shoot up and i come to a stop and drift backwards. I put it in park and try popping it down into drive again and nothing. I try reverse drive low 1 and low 2, nothing. Like anybody that owns and oldie I shut the truck off and let it have it's fit, while I think for a sec. I start it back up and gently drop it into drive and I didn't have any problems until about 3 or 4 miles of screwing around went by, and the same thing happened again, and I remedied it each time by shutting the truck off and starting it up again.

Then the time between restarting and losing gears got smaller and smaller... My dad had to pull me home with his truck and it's sitting down back.

I couldn't have lost a flawless tranny for no reason. The only thing I can think is that it was about 8 degrees out at the time. My dad told me that his 65 dodge acted like this, it would act fine when it was warm out but lose gears in freezing weather.

It's a Turbo 350 Tranny

Any and all help is appreciated.

EDIT: I should add that I checked all my fluids a few days ago, they're full and clean. No issues there.

[AJs72K5]

Hard to say... mine did the same thing, but it was warm out and was accelerating down the street when all of forward gears and reverse let go. No boom, no leaks, nuthin. Fluid was still clean. Could have been the pump, clutch pack, or the torque converter.

At that point, I ditched the TH350 and swapped in a 700R4.

[Mahlon Osterhout]

Well obviously I'm still open to hearing other ideas, but being that this is my first truck I'm a little low on knowledge with certain things. What transmission would you suggest for a mudding/trail truck? And how much would a used, but perfectly good, tranny run me? Just give me a ball park for that criteria.

[bouncytruck]

I had a transmission tank like that, but I got a huge grinding noise when i shifted from park to drive. Inside, one of the bearings exploded and shot shards everywhere. In a manner of seconds, it cracked several internal gears and cracked the case. There where no signs in the pan. I didn't find any issues until I was deep into the internal gears.

Pull the pan and see if you can see any signs. It could be simple like the pump or the torque converter.

[old man jimmy]

This may sound stupid, but it happened. Had a friend years ago, was out tooling around the hills. Went up a big rough hill, his buddy was bouncing around and his knee hit the transfer case stick into neutral. They walked out, came back the next day pulled truck home before he found the problem. Another thought, if your tranny is low on fluid, you may be sucking air at the filter. After it sets for awhile, the fluid would run back into the pan again, only to be sucked dry while driving. Just a couple thoughts. Good luck.

[66crewcab]

My 72 k-20 suburban trans finally took a crap without any notice! I pulled the trans and had it rebuilt! It was the pump! Also no notice and I just got back from a 800 mile trip!I paid about $650.00 to have the trans rebuilt with a new t-converter! That's with me pulling and reinstalling it!

[2fast55]

I just rebuilt the transmission in the truck in my avatar. It did exactly the same thing you described. It barely finished pushing cars the last race of the season, then just got so bad we had to push it up to the garage so i could drop the tranny out. Turns out it was the pump. The internal gears had eaten away the surface of the pump body so bad that there was no way for it to build good fluid pressure. The pump assembly itself isn't particularly expensive; neither are all the bushings and clutches that probably got destroyed when all the metal shavings got pumped into them. The labor to have someone else fix it will sure hurt your wallet though.

[blownz]

You might want to try and just service the trans with a new filter and fluid. It might be clogged in a way that going up and down sloshing the fliud around runs it dry.

Wayne

[HI OFCR]

Had a 79 do the same thing, The pump went bad and also burned up the converter. Sounds like a rebuild is in your future.

[Torrey72]

Originally Posted by Mahlon Osterhout

Well obviously I'm still open to hearing other ideas, but being that this is my first truck I'm a little low on knowledge with certain things. What transmission would you suggest for a mudding/trail truck? And how much would a used, but perfectly good, tranny run me? Just give me a ball park for that criteria.

If you have a TH350 it is best to stick with a TH350. The only problems which are minor with the TH350 is the weak sprag and low clutch clamping pressure due to GM engineering the tranny to shift smooth. You can fix the latter with a cheep shift kit and the stock sprag is fine unless you make serious horse power. Otherwise, for your second best bet. I would say upgrade to a TH400. But personally I like the lower first gear ratio of the 350 over the 400. And upgrading to something more exotic like a four speed automatic transmission would most likely be way out of the budget. The problem with changing to something other then a TH350 is that the adapter between the transmission and transfer case would most likely be different and would also need to be changed. This is more money then you want to start spending I bet. At first I was guessing you might have low fluid or burnt up clutches. But you say it's full and clean. And you did check the level with the engine running? When the engine is off, most of the fluid in the torque converter will drain into the pan giving you a false high level. I did have a buddy that broke a motor mount once and every time he would hog on it the engine and tranny would tilt just enough to pull on the linkage to kick it out of gear. But it sounds like that might not be your issue either? Hum..? I'm hung up on the clean fluid. I would drop the pan and look for metal fragments or clutch material on the bottom of the pan. Some silty black clutch sludge in the pan is normal for an old but good tranny. Metal is not good. but some microscopic metal glitter is ok. If you or someone installed the tranny recently they might not have seated the converter corectly on the pump and this can bust off the two dog ears on the pump gear. You would need to pull the tranny to change the pump if that happened. If you have bad seals or clutches in the tranny you would need to rebuild it. but if this was a problem your fluid should be brown and burnt smelling. The only way to buy a used tranny is to drive it before you buy it. Drop the pan and inspect it. otherwise you are more likely just buying someone else's problem. Sorry I'm not more help. If you need it rebuilt I wish you would do it yourself. TH350's are so easy with a good rebuild book. The most exotic tools you really need are two 6" C clamp to compress the cluch packs. A clutch and seal kit with a better sprag is less then $250. Having a shop do the work might be $2500 or something crazy.
Here is a link to the book I used to teach myself how to rebuild one.
Amazon.com: Turbo Hydra-Matic 350 Handbook... The book looks thick but 80% of it is History and theory and how to remove and install a th350. I guess I might of use maybe 40 pages of the book and just for the pictures mostly.

[IndyRich]

Take out the governor......I have a th400 so on mine it is behind a 4 bolt door on the passenger side of the tranny, I think it is on the driver side on a 350. Anyway it pulls right out and has a nylon gear on it that will wear down and prevent shifting.A new one was $40 on ebay, However, when mine went out I could alway drive in 1st gear, it just wouldn't shift so maybe that is not your issue, just thought I would throw it out there.