Mercedes 126 Restore – Transmission Service

The transmission within the Mercedes 126 is a really sturdy design, as one would count on. In its day, it was probably the greatest items accessible, which led Porsche to make use of it within the legendary 928. However as with all different programs on these automobiles, we should always not let the status for longevity cease us from performing frequent providers.

As a normal rule of thumb, transmission fluid ought to be modified each 30,000 miles. Not like trendy automobiles, the place the development is to eliminate 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 will take away virtually your entire fluid cost with out resorting to such gimmicks as energy flushes.

Whereas engine oil ought to be modified sizzling, transmission fluid is finest modified when merely heat to guard the mechanic from a really actual danger of scalding. The steps are as follows:

  1. Drive the entrance of the automobile on to ramps or assist on jack stands.
  2. Be sure that the torque converter drain plug is accessible. Except you may have been very fortunate, you’ll often have to blip the engine on the starter to get the plug to become visible by means of the entry gap. It may be “walked” the remainder of the best way with a big, flat-head screwdriver. It might 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 acceptable container. If doable, accumulate all of the used fluid in a single container after which measure it; it will assist us dispense the best amount once 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 may be rather more fluid right here than within the pan.
  5. When the 2 fundamental 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. Totally clear out the pan with a lint-free material and exchange the rubber gasket, making certain a correct match all the best way round. Reinstall the pan, torquing the bolts steadily and evenly as much as 10Nm. (The guide says 8Nm; a bit of extra is ok. However please do not go overboard: these pans may be warped and so they’re not low cost.)
  8. Substitute each drain plugs, utilizing new copper crush seals. Manufacturing facility spec. is 14Nm, or about 10lbs/ft. Tight with a three/eight drive works advantageous. If you happen to eliminated the cross-member, exchange it, being cautious to not cross-thread the bolts.
  9. (Elective) Crack open the trans cooler strains on the radiator (17mm wrench) and drain the small quantity of fluid from this space. Substitute the strains 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 contemporary Dexron-Mercon transmission fluid (ATF) by means of the dipstick tube. If you happen to can afford it, use artificial fluid: it helps maintain temperatures down by lowering inside 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 stage. You don’t need to be over the minimal mark at this stage. Transmission fluid expands significantly when sizzling; the reference marks on the dipstick are calibrated for decent fluid. So it’s o.okay. to be half-an-inch or so beneath that mark whereas the fluid is chilly.
  13. Drive the automobile for about 20 minutes (sure, not less than that a lot) to heat the fluid totally. Transmission fluid takes longer to heat up than the engine oil or coolant and requires the friction of precise driving to rise up to temperature. Verify the fluid once more on stage floor. Ensure you do not go away any lint on the dipstick earlier than changing it within the tube. Any stage between the marks is ok, however in no way can we need to exceed the utmost stage. If it’s essential to add fluid, accomplish that in very small increments and examine once more.

If you happen to used artificial fluid, you might discover that the shifts have develop into noticeably firmer. Compensate, if wanted, by adjusting the modulator valve on the driving 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 dangerous for the inner clutches.

Supply by Richard M Foster

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