Mercedes 126 Restore – Transmission Service


The transmission within the Mercedes 126 is a really strong design, as one would anticipate. In its day, it was top-of-the-line items accessible, which led Porsche to make use of it within the legendary 928. However as with all different techniques on these vehicles, we should always not let the fame for longevity cease us from performing frequent providers.

As a common rule of thumb, transmission fluid needs to be modified each 30,000 miles. Not like fashionable vehicles, the place the pattern is to put off service entry ports altogether, these Mercedes transmissions permit us to empty not simply the pan but in addition the torque converter. In different phrases, we are able to take away virtually the complete fluid cost with out resorting to such gimmicks as energy flushes.

Whereas engine oil needs to be modified scorching, transmission fluid is greatest modified when merely heat to guard the mechanic from a really actual threat of scalding. The steps are as follows:

  1. Drive the entrance of the automobile on to ramps or help on jack stands.
  2. Make it possible for the torque converter drain plug is accessible. Until you have got been very fortunate, you’ll normally have to blip the engine on the starter to get the plug to come into sight by means of the entry gap. It may be “walked” the remainder of the best way with a big, flat-head screwdriver. It could even be essential to take away the cross-member between the 2 entrance subframes (“dogbones”). The six retaining bolts have 17mm hex heads are are torqued to 45Nm.
  3. Loosen the transmission pan drain plug with a 5mm hex socket, then permit the pan to empty into an appropriate container. If doable, gather all of the used fluid in a single container after which measure it; this can assist us dispense the proper amount after we refill.
  4. When the pan has stopped draining, loosen the plug on the torque converter (identical measurement as on the pan) and permit the torque converter to empty out. There’s far more fluid right here than within the pan.
  5. When the 2 major flows have ceased, loosen the six bolts retaining the pan (13mm heads) and thoroughly take away the pan. Do not spill the remaining fluid throughout your self! Resist the temptation to wipe the innards with a store towel: we do not need any items of lint in right here.
  6. Take away and exchange the transmission filter, retained by Phillips-head screws.
  7. Completely clear out the pan with a lint-free fabric and exchange the rubber gasket, guaranteeing a correct match all the best way round. Reinstall the pan, torquing the bolts regularly and evenly as much as 10Nm. (The guide says 8Nm; a bit of extra is ok. However please do not go overboard: these pans might be warped they usually’re not low cost.)
  8. Change each drain plugs, utilizing new copper crush seals. Manufacturing unit spec. is 14Nm, or about 10lbs/ft. Tight with a three/eight drive works wonderful. In the event you eliminated the cross-member, exchange it, being cautious to not cross-thread the bolts.
  9. (Non-compulsory) Crack open the trans cooler traces on the radiator (17mm wrench) and drain the small quantity of fluid from this space. Change the traces if their situation is doubtful; they don’t seem to be costly. Retighten all connections.
  10. Utilizing a fine-mesh filter, add 4 quarts of recent Dexron-Mercon transmission fluid (ATF) by means of the dipstick tube. In the event you can afford it, use artificial fluid: it helps maintain temperatures down by lowering inner friction, and warmth is the primary enemy of computerized transmissions.
  11. Begin the engine and slowly add one other three quarts.
  12. Again the automobile off the ramps, run it by means of all of the gears, pausing for a few seconds between every gear, then examine the fluid degree. You don’t wish to be over the minimal mark at this stage. Transmission fluid expands tremendously when scorching; the reference marks on the dipstick are calibrated for warm fluid. So it’s o.okay. to be half-an-inch or so under that mark whereas the fluid is chilly.
  13. Drive the automobile for about 20 minutes (sure, no less than that a lot) to heat the fluid completely. Transmission fluid takes longer to heat up than the engine oil or coolant and requires the friction of precise driving to stand up to temperature. Verify the fluid once more on degree floor. Be sure to do not go away any lint on the dipstick earlier than changing it within the tube. Any degree between the marks is ok, however by no means can we wish to exceed the utmost degree. If it’s essential to add fluid, accomplish that in very small increments and examine once more.

In the event you used artificial fluid, chances are you’ll discover that the shifts have turn into noticeably firmer. Compensate, if wanted, by adjusting the modulator valve on the motive force’s facet of the transmission. Flip the little key counter-clockwise till the shift high quality is to your liking. Keep in mind that an excessive amount of slip is unhealthy for the inner clutches.