DIY Resealing Vickers Power Steering Pump W124

[brewtoo]

1990 300E. Did this job today. Had a leak of the front seal and the seal under the reservoir. New seal kit was in the $6 range.

I like to put the car on ramps; it makes it easier on the back not to have to bend over so far.

Remove the air filter and snorkel. Loosen the belt. Remove radiator shroud. Drain about a gallon of coolant into a clean container. Remove top radiator hose. Loosen belt AFTER you loosen the three pulley bolts on the PS Pump pulley. Don't forget to loosen the 19mm bolt on the tensioner first. Remove belt from pulley. Remove pulley.

Place a plastic cup under the return fitting. Loosen the return line and drain the reservoir into the cup. It's easier than sucking it out with a syringe like the manual says. Place a pan under the pump. Remove pressure line and let the remaining fluid drain into the pan. There won't be much. Hang the pressure fitting on the coil wire so it won't keep dripping. Remove the filter from the reservoir. My pump had a tie-wrap holding a couple of electrical lines on the back. Just cut it; don't try to remove the bracket.

There are FOUR bolts attaching the pump. They are all different. One bolt goes in from the back of the pump and also there's a long bolt with a nut in the back. There is just enough room to get your hand down in there. Loosening the back bolt can be tricky, though. A ratchet barely fits. Don't drop the bolt or the nut back there.

Remove the pump and clean it up. Remove the three 10mm bolts holding the reservoir and set it aside. Remove the four 13mm bolts holding the front on the pump and ease the guts out by holding the shaft. Mine was stuck together inside at this point but the back piece will break loose and pull off. Then you will see the clip that holds the impeller on the shaft and you will see all the little vanes. Remove the clip. Slide the shaft out. Now the impeller is sitting loose in the housing. Ease it out. Forget about trying to keep the vanes from falling out; ain't gonna happen. It's like herding cats. Remove the housing that fits around the impeller. Keep up with which way these housing parts are turned, just in case it matters. Now, you have the front housing with the seal in the nose. Pry the seal out. Lube the new one and tap it in with a block of wood or a socket. Don't go too deep with it. About level with the nose is correct.

Keep things clean with carb cleaner.

Lube the shaft and ease it through the new seal. Replace the housing that surrounds the impeller. Slide the impeller over the shaft and replace the clip. Now then, slip all the vanes back into the slots. The inside edges are square, the outside edge is slightly rounded. It's not hard. Replace the back of the front housing - the part that covers the impeller. Replace the two o-rings in the back half of the rear housing. Slide the new big o-ring down into the groove on the front housing and replace the little o-ring to the outside of the big o-ring. BTW, all the old o-rings are hard and flat. Pick them out by working a straight pin into them.

With the nose of the front housing pointed down (you don't want all your hard work to fall off the back), ease the rear housing onto the front housing. Replace the four bolts. Install the new reservoir o-ring and reinstall the reservoir. Replace the filter and rod. Put the lid on.

Don't put the pulley back on until the pump is secured on the engine or you won't be able to access all the bolts.

Installation is the reverse of the removal steps.

Don't forget to replace the coolant. Pour in some PS fluid, maybe half way up the plastic guide. It will bubble awhile as it fills the pump below. Recheck the level. BTW, my Factory MB manuals say ATF is fine. Suit yourself. I used PS fluid because I happened to have some. I also replaced the serpentine belt while I was there.

I started the car and backed off the ramps. The PS was working fine right off the bat and seemed to have no air in the system to bleed out.

Not too tough a job, just nasty if your pump has been leaking like mine was. The fluid was slinging off the pulley and leaving a stripe because of the front seal and that seal was as hard as a rock. During removal it just broke up.

Again, keep the inside of that pump clean. I used carb cleaner spray as I reassembled it.

Have fun!