replacing th350 seals? [Archive] - Team Camaro Tech

: replacing th350 seals?

Mar 7th, 03, 07:44 AM
How hard would it be to replace the seals that would cause a 73 Th350 to leak. I havent worked on trannys before but am willing to try if I can save a good deal of $$$. I bought a book on ebuilding them that hasnt arrived yet but would like ya'lls opinion.

Oldani Motorsports
Mar 7th, 03, 07:57 AM
Scott, no big deal! Look at getting a good quality pan gasket first. Not cork, but rather the black colored ones like any aftermarket trans company sells for performance use. They do not split and leak like cork. Put it on dry, no sealant. It is easy to replace the front and rear seals too. Just pop them out with a screwdriver, and tap new ones in. Lube the neck of the converter, and the yoke at the rear so they do not go into the new seals dry. I use Transgel, but a bit of ATF works good too. The converter will leak all over when you pull it, no biggie though. Just have some extra fluid on hand to refill the trans when you get it back in and running. The converter will "drop" onto the input shaft and then into the pump gear, usually with two distinct "drops" as it falls into place. A simple method is to look for about a little over an inch from the face of the bellhousing area, to the conveter mounting pads, when it is fully engaged into the trans. Also, the shift shaft seal can seep, and the time to do it is when the pan is off, unless you have access to the tool that fits over the shifter shaft lever arm after it is removed, and then the tool grabs the seal and it can be pulled out, without removing the shifter shaft. Those areas are the most common leak spots. Look at the seal on the detent cable housing where it enters on the right side of the trans. If it is leaking, do it with the pan off. You can see the linkage inside when the pan is off to confirm it is hooked back up correctly, not too hard to do either. smile.gif

Mar 8th, 03, 07:04 AM
Here's a couple more common TH350 leak spots besides the front and rear main seals and the pan gasket.

1. Dipstick tube. They use either an Oring or a cup shaped seal to seal the dipstick tube to the transmission. If you replace the O-ring get everything good and dry (no oil) and put a little bead of RTV on the end of the tube and oring before you pop it back in.

2. The speedometer cable. There are two little seals on the speedo cable. Everyone knows about the oring on the outside, but there is a little orange lip seal that goes around the speedometer gear that leaks easy. Just take the little screw out and pull the whole module so you can get a good look at it.

3. Shift linkage lever. There is a little lip seal that seals the shaft. You have to disconnect the shaft from inside the trans and pull it out then replace the seal.

Hope this helps.