Mercedes-benz w126 power steering pump replacement 1981-1991 s-class pelican parts diy maintenance article bad gas 6 weeks pregnant


The Mercedes-Benz W126 has the proud distinction of having 5 different drive belts. There are two belts that drive the power steering pump, and these belts also drive the cooling or water pump. If you are servicing or replacing your pump you do not need to remove the A/C belt, air pump belt or alternator belt to perform these jobs, but I do recommend if you are replacing the power steering pump to replace the power steering belts while you are in there. Also, it is very important to have two good belts driving the pump, if one of your belts goes bad or breaks replace it right away, never run the car with only one belt.

If you are replacing the belts you must first remove the air pump belt, alternator belt and A/C belt, please see our articles on removing and replacing those belts. After those belts are removed, you need to loosen the power steering pump to loosen the belt. There are three 13mm nuts holding it on. Loosen the two 13mm nuts attaching the pump to the front plate. With these loosened but not removed, loosen the 13mm nut on the lower driver side of the pump and then use a 13mm wrench from the back of that bolt to turn the toothed bolt in its gear. It is the same system as the other pumps. Turn the rear bolt counter clockwise to loosen the pump. You can now change the belts.

If you are replacing the pump you will need to remove the two steering lines connected to the pump, one is 17mm and the other is 19mm. Before you remove the lines make sure you get as much fluid out of the reservoir as possible. You can use a turkey baster or small hand pump to suck out as much fluid as you can. With the reservoir empty remove the two lines, some fluid will still drain out so be ready for it. With the fluid and lines removed remove the three 13mm nuts and bolts holding the pump to the bracket.

Take the pump to your bench and replace gaskets as needed. You will need a rubber wrench to wrap around the pulley to stop it from spinning if you are removing it, you can also try and wrap one of the old belts around it to hold it in place.

Replacing the pump is the reversal of removal. Once you have reconnected the power steering line and filled the reservoir, reattach the battery but DO NOT start the car. With the ignition unlocked turn the steering wheel curb to curb 30 times. This will help purge the air from the system, failure to do this will cause air to be trapped in the system and result in a noisy and improperly working rack. Make sure you fill the reservoir to the correct level as the system is very level sensitive.

What if there is no toothed bolt with it’s gear on the back of the pump pointed by yellow arrow on fig 5 ? How do I change the tension in this case? There is no mechanism there at all, just the flat head on the opposite side of lower 13 mm bolt… And this flat head is not twist-able, it sits tight in it’s place.

Comments: After removing the pump from the engine, draining all the fluid, removing the filter, and cleaning the outside of the pump to avoid contamination during handling, I removed the pulley by supporting the edge of the pulley on a large piece of wood, and tapping on the mounting nut with a soft mallet, being careful to avoid bending the pulley. After removing the pulley, remove the woodruff key from the slot in the shaft.

To remove the seal, I carefully stuck a screwdriver through the old seal, using light taps from my soft mallet, then gingerly used the screwdriver blade to pull the old seal out of the pump. Be careful to avoid marring any surfaces of the pump shaft or housing. I then inserted the new seal by hand, and then pressed it into place using a 19 mm socket, beginning with hand pressure, and then light taps with a soft mallet. The face of the seal should be flush with the front face of the pump housing.