The transmission in the Mercedes 126 is a very robust design, as one would expect. In its time, it was one of the best units available, which drove Porsche to use it in the legendary 928. But as with all the other systems on these cars, we should not let longevity reputation prevent us from performing frequent services. 19659002] As a general rule, the transmission fluid should be changed every 30,000 miles. Unlike modern cars, where the trend is to completely remove the ports of access to service, these Mercedes transmissions allow us to drain not only the pan but also the torque converter. In other words, we can remove almost any fluid load without resorting to such gadgets as hot flashes.
While the engine oil needs to be changed hot, the transmission fluid is better changed to heat the mechanic. boiling. The steps are as follows:
- Drive the front of the car on ramps or stand on candles.
- Make sure the drain plug of the torque converter is accessible. Unless you have been very lucky, you will usually need to attach the engine to the starter so that the plug is visible through the access hole. It can be "walked" the rest of the way with a large flathead screwdriver. It may also be necessary to remove the crossbar between the two front subframes ("dogbones"). The six retaining bolts have 17 mm hex heads and are tightened to 45 Nm.
- Loosen the transmission housing drain plug with a 5 mm hex socket and allow the bucket to drain into a appropriate container. If possible, collect all used fluid in a container and measure it; This will help us distribute the right amount when we fill.
- When the tank has stopped emptying, loosen the torque converter cap (the same size as the tank) and allow the torque converter to drain. There is a lot more liquid here than in the pan.
- When the two main flows have stopped, loosen the six bolts that hold the pan (13 mm heads) and carefully remove the pan. Do not spill the remaining liquid on yourself! Resist the temptation to wipe the bowels with a shop towel: we do not want lint here
- Remove and replace the transmission filter, retained by Phillips screws.
- Thoroughly clean the pan with a lint-free cloth and replace the rubber gasket, ensuring a good fit all around. Reinstall the pan, tightening the bolts gradually and evenly until 10Nm. (The manual says 8Nm, a little more, it's fine, but please, do not go over: these pans can be deformed and are not cheap.)
- Replace the two plugs emptying using new copper seals. Factory specification. is 14Nm, or about 10lbs / ft. Tight with a 3/8 drive works well. If you removed the crossbar, replace it, being careful not to cross the bolts.
- (Optional) Open the trans cooler lines on the radiator (17mm wrench) and empty the small amount of fluid from this area. . Replace lines if their condition is questionable; they are not expensive. Tighten all connections.
- Using a fine mesh filter, add four quarts of fresh Dexron-Mercon Transmission Fluid (ATF) through the gauge tube. If you can afford it, use synthetic fluid: it helps reduce temperatures by reducing internal friction, and heat is the number one enemy of automatic transmissions.
- Start the engine and slowly add three quarters more.
- on the ramps, pass it through all the reports, pausing for a few seconds between each report, then check the fluid level. You do not want to exceed the minimum score at this point. The transmission fluid expands a lot when it is hot; The reference marks on the gauge are calibrated for the hot fluid. So it's o.k. to be about a half inch or less below this mark while the liquid is cold.
- Drive the car for about 20 minutes (yes, at least as much) to heat the liquid thoroughly. The transmission fluid takes longer to warm than the engine oil or coolant and requires the friction of the pipe to reach the temperature. Check the fluid again on a flat floor. Be sure not to leave lint on the dipstick before replacing it in the tube. Any level between the marks is correct, but we do not want to exceed the maximum level. If you need to add liquid, do it in small increments and check again.
If you used synthetic fluid, you may notice that the changes have become much firmer. Compensate, if necessary, by adjusting the modulator valve on the driver's side of the transmission. Turn the small wrench counter-clockwise until the quality of the change is to your liking. Keep in mind that too much slippage is bad for internal clutches.