Where did I go wrong?
 

Changed the transmission fluid, filter, and pan gasket in my 85 300TD on Sat. I bought cheap Dexron III at Wal-Mart (Super Tech). Following the DIY's on this site, I drained the torque convertor fairly easy and I also drained and removed the pan without much hassle. I did not torque the drain pain, but I tightened the bolts in a criss-cross pattern, and after filling with the appropriate amount of fluid (once again following the DIY's on this site), I checked and found no leaks the day after.

Fast forward to Monday night. I had a change of heart on the Wal-Mart fluid so I went out and purchased Mobil 1 synthetic ATF. Drained the torque convertor and pan again, but I did not remove the pan or change the filter. I measured exactly 5.2 quarts of drained ATF fluid. As I was pouring fresh quart number 4 into the transmission dipstick tube, I heard ATF fluid gushing out of what seemed to be the top of the transmission pan. Yes, I did replace and tighten the drain plugs on the pan and torque convertor. The leak seemed to be coming from the gasket, but I couldn't pinpoint it as there was fluid all over.

Did Mobil 1 ATF cause this leak or is my stupidity to blame here? Why didn't the gasket leak when I first changed the fluid? Was it wrong not to change the filter?

Frustrated and ready to give up on the home mechanic impersonation.

Don't despair. Nothing better than a night of good rest to give you fresh ideas on that tranny. I personally am not an expert on transmission work, but there's several members who have had their fair amount of work on them who periodically check these threads. You'll get your answer one way or the other. Personally, to me it sounds like you forgot to tighten something in there. Or maybe it was overtightened and the thread is now either flush or broken at some point, in which case I'd replace the pan altogether. Don't quit though. Once you fix it, you'll have learned a lesson and be glad you pressed on :D

First thing is to check the bits you have removed and refitted. If you are not sure about something why not post a photograph?

No Comment
 

('On your NEGLECTING to R+R the Pan and Filter the Second time.)

[In life, as in things, MERCEDES... The shortcuts will ALWAYS come back to bite you in the Posterior]

Howeveah, The Torque Specifications in the FSM ,if not followed EXACTLY as
specified, have ****** Much Better "Shade Tree (s)" than you OR I will ever be!

99.99999% Chance that you've "OverTorqued" the Tranny Pan Bolts!
[And as a result , "Warped" the Tranny Pan Flange]

It (The Pan) Can be "Adjusted" by flipping upside down on a PERFECTLY level
surface ,so you can "Bang out" the Imperfections in the "FLANGE".
(A tiny Ball Peen Hammer need not be the Implement of Torture the Inquisition
named it...It can be a Precision Machine Tool in the right hands!)
[You've just turned yourself into a cross between Two different Guilds...
Blacksmith and Engineer.]

Converter Empty
 

You may very well have a leak but there is also a good chance it is just temporarily overfilled because the converter is empty and if you started the engine briefly to get the pump going it would fill the converter and there would be room in the pan for the rest of the fluid.

:)

To get the fluid into the convertor, is it safe to start (even for a few seconds)? There is probably 3 quarts of ATF in the pan.

Checked the tranny dipstick cold today and the fluid was about 2-3 inches past the full hashes. That seems to explain things.

Thanks for all the help guys.

George

Carefull!
 

Hi George,

For my transmission I need to check the level when it is HOT engine running and in park. If you check the dip stick when it is cold and the engine isn't running then you get an artificially high reading. My car is a 1981 w123 300D - I'll look up the transmission number and post back here. It is 'the one' that has no drain plug - you drain by undoing the filler pipe banjo...

Yeah I have never heard of checking it anyother way but
up to full temp level ground

You never did mention wether you drove it sat.-mon. after the fluid ect. change

after I change any trans fluid filter ect.
I always start it let it run a little bit
check fluid level
pull it in all gears one by one
and let it roll about 10-20 feet in each gear
starting out in the lowest than up though
including reverse

to let the fluid flow though all the passages
for each gear

check level again (on level ground while at full temp )
then drive it and check it again

this is probally more than is required or more than most people do

but "good enough" isn't
GOOD ENOUGH for me

I am too particular or anally retentive as my friends say

your trans dipstick get tweeked could it be leaking there?
if all else fails just do the job again step by step it's not that hard

The 85TD is a California emission thus it has the Cali trans - 722.416. I drove the car extensivley Sat-Mon with no leaks.

I was only going to start the car for a brief moment so the fluid can get into the torque convertor from the pan. I didn't want to check the fluid hot out of fear there was a very low amount of fluid in the pan.