Th350 transmission shifts and works great but leaks . What would be a simple kit to get or should I do a deep overhaul

 

Where does it leak? Could be as simple as an o-ring.

 

Find out exactly where/what is leaking and then decide.

 

Thought it was from front of the pan torque converter side but its from up in side like behind the TC maybe the pump seal ? Not sure . But do all kits come with what is needed for the pump to rebuild also ? I don't want to spend 300 on a rebuilt kit and it's not " everything" you need , then have to run around and buy other parts individually. Is there a reasonable priced good kit that has everything.?

 

Sounds to me like a converter seal might do the trick. Check pump seal carefully as best you can if trans is still in car, or be sure to check if converter is out. Clean off well & try to determine if leak is just converter seal and/or pump seal. Good idea to check shift shaft seal and dipstick O ring while you’re snooping.

 

Throughly clean everything.

Go to your nearest parts store and buy a bottle of A/C oil with the fluorescent dye. Add a little to the fluid, drive the car 10-15 miles. Once the drive is over, raise the car again. Get a black light and look for the fluorescent dye, it will highlight the leak enough for Stevie wonder to see.

A paper and rubber kit will include every seal and gasket needed to completely reseal the transmission. More than likely, it’s not the seal around the converter. Those don’t leak, they hemorrhage fluid. Carefully inspect around the kickdown cable, and especially the transmission fill tube. They tend to corrode around the groove for the o-ring and crack. If the tube in fact is the issue, get a replacement that uses the later boot style seal.

Does the car have the transmission controlled spark? The oil pressure switch is another leak possibility. Further back is the o ring for the vacuum modulator, and the seals for the speedo gear housing.

A TH350 is one of the easiest transmissions for a novice to build. They are simple, straightforward, and require almost nothing as far as special tools. What special tools are required is easy to fabricate. However, if the transmission works, unless you want to rebuild it if just fix the leaks. It’s starting to get nice outside, use the downtime in the winter to rebuild it if you want.

 

I had a trans leak for along time and always thought it was the pan gasket or warped pan. It turned out to be the shift shaft seal, cheap and easy fix.

 

I will add to this, I just went to prep the 72 Cutlass and there was quite a bit of transmission fluid. I crawled under and hope it is an easy fix. I took the attached pics there was what looks like a return hose that was a little loose, I tightened it and put new cardboard. Would that be the leak or is there other issues


Hose was not completely tightened.

 

That’s the speedometer cable, not a “return hose”. There should be a seal in there.

 

Not to steal or thread.
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I am wondering if this is my problem, a few weeks ago I noticed a puddle of tranny fluid under my 70 cutlass with a th400.
The rear tire went low on air and the car was tilted was the only thing new. I tighten the tranny lines, pan, and aired up the tire and it seems better.
After checking today it seems like it's coming from the torque converter seal. The engine hasn't been started for nearly 6 months.
I would estimate that it lost close to a qt of fluid.

Does it make sense the converter seal can go bad while just sitting there without running the engine or driving it?

 

that was the only thing new to mine now that you said it my rear passenger tire went flat and my front passenger suspension is sagging . Could it be from a tilting issue.? Mine was like half a qt. Of fluid

 

Thanks Fun71, will check that out. I had tightened it and put new cardboard under. going back on Wednesday to check .

 

Adding to this for some advise. I had leak coming from the Speedometer housing, so I bought a new one and replaced it. Figured that while most of the fluid was out of the transmission, I would change the gasket. I have all the fluid out and all the bolts, but cannot get the pan out. Is there a trick to getting out? There is a bar bolted somewhat over one side (in picture) but cutouts so you can get to the bolts, but the pan just won't come out. Help...

 

The transmission mount is probably collapsed. that causes the transmission to sit lower than it normally would.

Take out the 2 bolts that hold the transmission mount yo the crossmember. Position your floor jack under the transmission extension housing. Be careful not to put the jack on the driveshaft yoke. Slowly raise the transmission, stop when the transmission hits the floorboard. The pan will probably fall out.

If the mount is squishy and oil soaked, replace it.

 

The pan may be stuck (glued) to the trans, you may need to gently pry it off.

 

And drop the front first, then the rear edge under the cross member can be wiggled out easier.