Mercedes 126 Repair – Forgotten Fluids, Part I

Even though most responsible Mercedes proprietors keep in mind to change their motor oil reasonably frequently, not all people remembers to glimpse just after the other lubricants on the car. This short article focuses on arguably the most seriously neglected fluid: the gear oil in the rear differential.


Most Mercedes 126 automobiles have “open up” differentials, although a several of the afterwards designs came with constrained-slip differentials. The former do not call for a great deal notice and are, in actuality, very sturdy. Scorching-rodders have uncovered that the rear differential on the 380SE can manage as a great deal as 800hp by the rear wheels. But, that does not mean we can overlook about it completely. The gear oil should really be improved at roughly 100,000-mile intervals, or each 50,000 in serious service. If still left in way too long, it will sooner or later drop its ability to lubricate and begins to resemble frothy pea soup! (It does not odor way too excellent, both!)

Fluid capability is only about 1.five quarts, so there&#39s no excuse not to use the “excellent things.” Amsoil, Redline, and Royal Purple all make significant-excellent synthetic gear oils, ordinarily with 75W-90 viscosity. Just as with an oil change, this is finest done with the fluid at running temperature. The two plugs in the differential – higher fill and reduced drain – get a 14mm hex important and are normally very hard to budge. A long breaker bar will be demanded. Make confident that you loosen the filler plug initial, due to the fact if you remove the drain plug and then uncover the filler is trapped, you&#39ve received a bit of a difficulty. Melting an ice cube in the filler plug&#39s 14mm-fitting may support loosen it by thermal contracting.

Refilling is a great deal much easier with a modest oil pump. Basically fill until eventually the gear oil is amount with the filler hole when it begins to see out of the threads you know you&#39re done. To be certain an precise fill, the car should really be amount throughout this operation, although this is not significant. If you leave the rear of the car up on jack stands, a slight overfill will ensue. Torque the plugs to 50Nm (37 lbs / ft).

Resource by Richard M Foster

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