Mercedes Coupes/Sedans/Wagons 1974-1984 Repair Guide

Rear Axle

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FLUID LEVEL CHECK



See Figures 1, 2 and 3

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Fig. Fig. 1: To check the differential housing fluid level, use an Allen wrench to loosen the filler plug ...



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Fig. Fig. 2: ... then remove the filler plug from the housing



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Fig. Fig. 3: If the lubricant is not level with the bottom of the filler hole, add fluid to the proper level

The rear axle lubricant should be checked at the interval specified in the chart, or sooner.

  1. Before checking the rear axle lubricant level, be sure that the vehicle is on level ground.
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  3. Slowly unscrew the drain plug from the oil filler hole (upper hole). You will need a 14mm hex allen wrench. If the lubricant level is satisfactory, lubricant will begin to seep past the threads of the plug. If lubricant does not seep past the threads, remove the plug entirely. The lubricant level should be up to the bottom of the filler hole. If not, lubricant can be added through the filler hole by using a pressure gun. Add only enough lubricant to bring the level to the bottom edge of the filler hole.
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Rear axles without limited slip may use any high quality SAE 90 hypoid gear oil. The limited slip differential can be filled only with special Limited Slip Special lubricant available at Mercedes-Benz dealers. Identification of this type differential is by a plate attached to the rear axle housing, reading "Achtung Spezial Sperr-differential." (Caution! Special oil limited slip differential.)

  1. Replace the oil filler plug.
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DRAIN & REFILL



See Figures 4 and 5

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Fig. Fig. 4: To drain the fluid from the differential, use an Allen wrench to loosen the drain plug ...



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Fig. Fig. 5: ... then remove the plug and drain the fluid into a suitable container

The rear axle need not be drained regularly, but if desired, the car must be on a level surface with the weight on the wheels or with the axle tubes supported by jackstands. This is necessary to prevent oil from entering the axle tubes.

  1. Remove the bottom drain plug and loosen the top drain plug.
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  3. After the fluid has drained, replace the bottom drain plug using a new washer.
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  5. Refill the unit with the specified lubricant. Be sure that the proper lubricant is used. Consult the "Oil and Fuel Recommendations" section.
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  7. Replace the top plug using a new washer. The fluid level should be at the top of the oil filler opening.
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