Ive been trying to chase these leaks on my dads cutlass for a minute now, and i used the baby powder trick to figure out where one was atleast (shifter shaft seal)
However ive got another on the passenger side going up to the dipstick but im not sure if theres anything else here that could show a leak too. Thank you

 

Best thing to do is clean the areas first, then start the car and see where the fluid is coming from. It blow/migrates to other areas when the car is moving. The dipstick tube grommet is Dorman part 65113 if it needs to be replaced. Areas that leak are pan, governor cover, speedo, shift linkage, kickdown cable and modulator.

 

Thank you! Im waiting on the govenor cap clip to come in soon actually; i found out it popped off (somehow) and made the cap cause a leak.
Where would the kickdown and the modulator be?

 

I find these old transmissions leak everywhere. The kick down cable is by the cooler lines in front of the dipstick tube. The modulator is on the pasenger side back and held on with a forked bolt on clip with an O ring on the modulator inside near the tail shaft housing. Good luck, you will need it to eliminate all the leaks. I like my current 4L80E for the lack of leaks as much as the strength.

 

You'll have better luck finding a virgin at a sorority house than getting a th350 or a 400 to stop leaking. The best you can hope for is it being damp and not really dripping all the time.

 

Modulator location THM350

 

Thank you!

 

If the car sits for long periods of time the fluid in the converter will drain out into the case/pan. These seals are not designed to hold back "standing" fluid and will leak. Shift shaft seal is #1 to leak. Pan gasket and dipstick tube also.

 

None of my Th400 or TH350s leak anything over the winter. Biggest thing is of course new seals but get rid of the stock torque converter. I believe that's part of the problem.

 

Try adding some ATP AT-205 leak sealer to the transmission fluid. It helps swell up seals and may stop your leaks.