73 Eldorado trans. leak after sitting for Months.

[Mark03]

Hi, have a 73 Eldorado with 30,000 miles on it. After winter storage or if it sits for a couple months, end up with a good size puddle of transmission oil on ground. Appears to be from around the dip stick area, can't tell for sure. Anybody have a fix for this problem? Thanks Mark

[35-709]

Drive the car.  Not usually a leak but an overflow out the vent when the 12.5 quarts of fluid or so all drains down after long periods of inactivity.  When the car is driven on a more or less regular basis you won't see that.  Have seen this happen a couple of times on TH400s/TH425s that have sat for a time.

[TJ Hopland]

Mine used to do that pretty bad.  Over the winter I would have to buy one of those big trays and fill it with kitty litter so I didn't make a huge mess at the storage place.   One year it had gone down so far I could not even drive it out of the storage place without adding several quarts.    I know big problem areas were the electrical connector and shift shat as well as the dip stick off and on.   

Took 2 trips to a shop a few years ago that did a lot of other work for me and they finally got the regular leaks slowed down to just drips and that also seemed to mostly solve the over the winter massive puddle too.    Shift shaft is still the worst leak on mine.  These don't have a lip seal like a lot of the 400's had just an o ring.  Also was supposedly impossible to do in the car but my shop said they knew a trick.  My guess is the bore is worn and needs a bushing and maybe fitted for a lip seal if possible.

I do remember replacing the O ring on the dipstick several times.  IIRC its kinda a odd squared off one and took me several tries to get anything even remotely close.   I'm pretty sure that was one of the things the shop mentioned working on but I have not looked close at it to see what they did.

Mine was rebuilt about 20 years ago and has got regular fluid changes.  Torque converter was new back then and hasn't been changed since.   I think one of the times I had it and the engine out we did replace the font seal just because it was easy to do.  I have heard that the chain cover is a common place for leaks but is the one place on mine that has never leaked.   

[Roadmaster75]

Hi, have a 73 Eldorado with 30,000 miles on it. After winter storage or if it sits for a couple months, end up with a good size puddle of transmission oil on ground. Appears to be from around the dip stick area, can't tell for sure. Anybody have a fix for this problem? Thanks Mark

Gravity is pulling on all that trans fluid as the weeks and months go by without being driven......
There’s  probably 3 quarts in the torque converter looking to drain out thru a weak seal or o ring (dipstick).
The easy solution is start it more often to circulate all that fluid. 

[bcroe]

Yes, it drains down and the higher level finds any leaky seals.  You
need to find them and see about fixing them.  The worst is the poor
design of the rear chain cover.  In that case the fix is pull it and
GLUE the cover back on.  good luck, Bruce Roe