WheaYat

ok so just as i thought i could move on to my next project....... this damn leak will not stop, its not the dipstick tube, its not the front seal, they been changed, along with a new pan and gasket of course. this is what i dont understand. when the car is runnin' and drivin' not a leak in sight. even after the car sits for 6-8 hours, NO LEAK. but right after about about 12 hours, here it comes. dripping away !!!! WTH ! anyone have any ideas or history with the same issue? Felpro composite gasket was put on dry. have done this twice. seems to be leakin from the left and right side rear of the pan. what can i do. i mean is it possible to stop completely? i here they always will leak?? any help thanks and God Bless

compedgemarine

my TH400 dont leak. usually if it leaks after sitting awhile it is because the fluid is draining out of the converter back into the pan. (one of the reasons you have to have it running to check the fluid). I would look at anything that is above operating level. you need to clean it good and then let it sit to see if you can spot something. could be a variety of things like a crack in the dipstick tube, porosity in the case, speedo housing, tailshaft gasket, etc.

jeffu231

Check the down shift cable on the passenger side right behind the dipstick tube. Simple O ring seal and it will leak after sitting if bad.

matt69olds

or possibly the shift shaft seal.

Blk71SX

say that 5 times real fast

OLD SKL 69

x2

I would check that first.

WheaYat

thank u guys alot. I had changed the down shift o ring along with the dip stick o ring all that is good and dry.

Lady72nRob71

Mine is leaking where the speedo cable is attached - makes the pan looks like its leaking.

Hopefully yours is dry for good now!

d2_willys

If the transmission starts leaking while driving, check the 2nd gear accumulator cover on the passenger side, just above the pan centered front to back. The O-ring goes bad and leaks only when driving, but not when idling or stopped.

cutsupreme72

Looks like I am a few years late on a response LOL! In no way am I an expert on transmissions or even cars for that matter, I'm a diesel mechanic with a love for my olds! I had the same problem but it was leaking on the passenger side up front. I have a 72 supreme and I went crazy trying to find the leak. As of yesterday I finally tackled the demon! It will not leak just sitting but leaks heavily in reverse and I assume in Drive @ higher speeds. I replaced the front and rear seals, dipstick seal, TV cable seal, pan and gasket and it still leaked! I couldn't find the leak until I decided to have my Girlfriend put the car in D and R while I was underneath (if that isn't trusting love I don't know what is.....) I finally found that the TCS (transmission controlled spark, I guess? sensor is faulty. Tranny fluid is leaking out of the sensor where the spade is. It is impossible to see it with the connector on and I could never locate it looking from front to back. It was when I looked at the switch from back to front I see it streaming from the switch. ( I assume as I have a chip in the back of the switch connector.) ordered a new one and problem was solved. I know they put these on smog cars (mine being a CA car) I hope this helps someone out as I get OCD knowing there is a huge leak somewhere that I cannot fix! You guys have been a huge help with my questions so I hope my reply helps someone down the line!