Where did I go wrong? - PeachParts Mercedes-Benz Forum

gvran71 · #1 06-08-2010, 01:31 AM

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.

cirrusman · #2 06-08-2010, 02:22 AM

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

Stretch · #3 06-08-2010, 04:08 AM

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

compress ignite · #4 06-08-2010, 04:22 AM

('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.]

fdanielson · #5 06-08-2010, 05:44 AM

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.

vwbuge · #6 06-08-2010, 05:59 AM

Quote:

Originally Posted by fdanielson

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.

gvran71 · #7 06-08-2010, 07:52 AM

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.