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W201, W212, W221, & W222 Moderator
'84 Euro 500SE, '85 Euro 2.3-16, '51 Euro 170S, '97 Jeep Wrangler Sport, '15 G63 AMG
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Discussion Starter · #1 ·
In this write-up, I'll be detailing how to disassemble your Zahnradfabrik (ZF) Steering Pump. For those of you who have the Vickers, I'm sorry, this will not help you.

Now, I made the mistake of not taking any photos of the initial removal process of the pump from the motor, but it's so simple that you don't really need them.

The reason I am doing this, is because I had a slow leak coming from the front seal of my pump. Looking at the backside of the pulley, I could see ATF from the unit (Gen 1s use ATF, Gen 2s use PS fluid) pooling in it. There was also clear evidence of it having run down all over the AC compressor and various other components that happened to be underneath the pump itself.

Since I've replaced the seal, everything is bone-dry as it should be, and the replacement filter and flushing of the fluid has done the system some good.

Without further ado, let's begin!!

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Step 1 - Drain the system:

You have two choices to drain the system:

Option 1 is to drain from the steering box itself, turning the wheels to the left to force as much of it out as you can.

Option 2, which is what I did, use a MityVac with the reservoir attachment or a turkey baster to remove all of the fluid from the pump reservoir itself.

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Step 2 - Remove the old filter and siphon remaining fluid:

There is a 10mm nut that holds the plastic sleeve and spring in place. That spring is was holds the filter down.

Once those items are out of your way, simply grab onto the old filter with a pair of needle nose pliers.

For comparison, old and new:


Afterward, siphon out or ensure drainage of any residual fluid at the bottom of the reservoir.

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Step 3 - Remove all hoses:

You'll want to remove the return line hose first, since it's a little easier to reach. You can do this with a 3/4" box wrench. Be warned that there may be some leftover fluid in the lines, so have a bottle, cup, or just a shop rag handy to catch anything that might come out.

Next, you'll remove the outlet hose which feeds the steering box itself. A 17mm box wrench will do just fine here. As with the return line, you'll want to watch out for residual fluids.

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Step 4 - Remove the pump from the motor:

There is a belt tensioner that you may want to loosen (I actually didn't). It's loosened via hex-key.

Once you've done that, there will be three nuts that are to be removed with a 13mm box wrench, or if you can squeeze a socket wrench in there, you may do so.

Gently pull the pump toward you, and the belts will slip right off, no big deal.

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Step 5 - Get that pulley off!!:

Here comes a somewhat fun part, you'll want to secure the pulley in your handy vice so you can get at the nut that holds the pulley on.

*Note! If you haven't ensured that your pump is as empty of fluid as it can be, it will rotate upside down and make a mess all over your garage floor.*

The nut will require you to use a 22mm socket, and a breaker bar will do wonders. It was late, so I didn't use any impact tools:


Once you've got the nut off, it's time to break out the puller to get that pulley off. You can probably use all three arms, but I did it with just two. BE ABSOLUTELY CAREFUL WHEN PULLING IT OFF, THE WOODRUFF KEY WILL BLAST OFF TO SPACE. If you go slow and keep a good eye on things, you won't have to worry about that.

So here it is, all setup and ready to go. EzMode engaged:




Here you can see the residue from fluid leakage on the backside of the pulley:


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Step 6 - Inspect that front seal:


Pretty straight forward, look at it:


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Step 7 - Give the pump a good exterior cleaning:

Before I moved on, I decided to go ahead and clean the pump exterior so I could get that out of the way.

Here's a before picture (before I even pulled the pulley):


Here's the after shot, I didn't go too crazy, just wanted it better than before:


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Step 8 - Get that old front seal out and inspect that rear seal:

The kit I order from Mercedes Source offered a specialized punch to dig into the seal and pry it out. Unfortunately, my seal was so brittle, that the punch method didn't work.

In light of this discovery, I've actually found it would be best for everyone who attempts this, to actually remove the internals of the pump. This will give you an opportunity to inspect the rear seal (there are two, actually, but that will be discussed later).

I neglected to take photos of this part, but you'll want to use a 6" C-clamp or larger to push in rear cap. There's a c-clip retainer on the back that you'll want to make a note of exactly how it's placed.

After that cap is removed, inspect the first rubber seal, they don't usually seem to go bad but it's worth checking out:


Once you've gotten everything removed (it is imperative you remember exactly how everything went in, there will be witness marks to help), go back to removing the front seal.

This is how it looked after having attempted the punch method:


Not the desired/intended result of the kit, but there's more than one way to skin this cat.

I grabbed my adjustable pliers, and rocked it out slowly:


Comparison of the old and new seals:


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Step 9 - Inspect the rest of the pump and its internals:

You'll see that second internal seal I mentioned, it too doesn't seem to be a common wear part:


Inspect the internal components for any kind of wear or other damage:




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Step 10 - Reassemble pump:

Reverse the steps you took to get to the rear seal.

Neglected the photos here too, but you'll want to use your C-clamp to push the rear cap in so you can get the clip into place.

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Step 11 - Install new front seal:

Apply a thin layer of ATF to the inside lip of the seal. Then apply a thin layer of the gasket sealant included in the kit.

Gently slip the seal on, and push it down as far as you can by hand. From there you can take your trusty 22mm socket and gently hammer the seal into place:


Here's the finished result, all nice and flush:


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Step 12 - Reinstall pulley:

Insert the woodruff key where it's supposed to be, place the pulley back onto the pump and gently tap it into place.

Secure the pulley/pump to the vice once more, then torque down the nut to about 58 foot-pounds:


Step 13 - Mount the pump back in the car, and get that new filter in:

Reverse the steps you too to remove the pump, ensuring the belts are lined up properly.

When it's done, you should end up with this:


Insert the new filter:


Put the spring and sleeve back on, and tighten it down:


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Step 14 - Perform a flush:

If you've recently flushed your power steering fluid, you can bypass this step and proceed to step 15.

The first thing you'll want to do is reconnect the outlet line to the pump. You'll want to take the return line and put it into a container of some sort to catch all the fluid you flush out.

Remember to use only MB-Approved milk jugs:


You can set up how you want to catch the flushed fluid however you like, this was just my method.

For this next part, it'll help to have a helper, but you can do this by yourself.

Fill the reservoir up to the outlet. DO NOT GO FURTHER OR FLUID WILL POUR OUT OF THE RETURN LINE HOLE!

With your ATF (or power steering fluid for those with later generation vehicles) in hand, have your helper crank the car. Begin adding fluid immediately still using caution as to not overfill and have fluid pouring out of the return line hole.

Continue with this process until you can see that the fluid is running clear. Have your helper shut off the vehicle when you've determined the system has been sufficiently flushed. Beware that fluid may squirt out at you upon vehicle shut off.

Reconnect the return line to the pump, and proceed to step 15.

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Step 15 - Fill and bleed the system:

Fill the reservoir about 1/2" from the top. Start up the vehicle and turn the wheels left to right 2-4 times to bleed the system of air.

Shut off the vehicle and inspect the fluid levels. Add fluid as needed.

Repeat the steps of turning the wheels from side to side to ensure that all air has in fact been purged from the system. If there are no drop in fluid levels, top it off to where it needs to be.

Lastly, go for a drive and check for any leaks. Monitor those fluid levels and check behind the pulley for any pooling that would indicate the seal has failed or isn't seated properly.

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As always, this is a living, breathing thread, so if requests are made for updates or additional info is requested, I will add to it as I can.

I hope this helps those with ZF pumps who wish to tackle this on their own as opposed to paying some indy to do it for them.
 

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1991 560 SEC 1994 E500 2014 E350 Cab
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very nice contribution! Especially the line at the end of step 14 "squirt out at you upon vehicle shit off"
 
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W201, W212, W221, & W222 Moderator
'84 Euro 500SE, '85 Euro 2.3-16, '51 Euro 170S, '97 Jeep Wrangler Sport, '15 G63 AMG
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Discussion Starter · #5 ·
very nice contribution! Especially the line at the end of step 14 "squirt out at you upon vehicle shit off"
:eek: I was half asleep when I wrote this!! :yelrotflmao:

Excellent, Josh. Where's the GoPro video version? :rolleyes:
Alberto, the GoPro is mounted to the 190E at the moment! I need one of those helmet mounts to do that.

I have to admit my Lumia 1020 does a fantastic job of taking photos.

Patience is definitely something you want to have when doing this, but the end result is worth it, even at the risk of being splashed with ATF when the vehicle has had it with your fiddling around and "shits" off :eek:

Flushing the system alone demands superhuman speed and reflexes, but it is doable; best to have someone around to help though.

This is also a prime opportunity to inspect belts and pulleys and clean up around the front of the motor.
 

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84 500SEL AMG, 90 560SEC AMG, 85 500SEC AMG Widebody
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I rebuilt a PS pump as well. Couple of comments to add - when taking the pulley off after removing the large nut, I also used a wheel puller and bent the pulley trying to get the pulley off the shaft. Ruined the pulley. Luckily, Jono had a spare pump and showed me how to remove the pulley - after the nut is off, simply hold the pulley perimeter with one hand and hit the shaft end hard with a hammer and the pulley will pop off (have the pump just above the ground so it doesn't fall too far).

Also, the large rear cap that has to be depressed using a large C clamp (it is spring loaded with a large stiff spring) - when re-installing the large rear cap, the C clamp has to be exactly in the middle of the rear cap so the cap releases straight. I had to push in/release the C clamp a few times to get the cap to sit straight. This process is slightly challenging because the pump is a little heavy and bulky. Having a large vice helps.

Al
 

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W201, W212, W221, & W222 Moderator
'84 Euro 500SE, '85 Euro 2.3-16, '51 Euro 170S, '97 Jeep Wrangler Sport, '15 G63 AMG
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8,890 Posts
Discussion Starter · #8 ·
To catch the woodruff key, you could put the whole thing in a plastic bag probably... That's what I do with certain guns when I disassemble them, as many have tiny spring loaded parts that you will never see again if you aren't careful.
I learned that all too well when I first started working on guns. Luckily I was in an empty room where anything could be found! But those springs and plungers do love to fly.

I rebuilt a PS pump as well. Couple of comments to add - when taking the pulley off after removing the large nut, I also used a wheel puller and bent the pulley trying to get the pulley off the shaft. Ruined the pulley. Luckily, Jono had a spare pump and showed me how to remove the pulley - after the nut is off, simply hold the pulley perimeter with one hand and hit the shaft end hard with a hammer and the pulley will pop off (have the pump just above the ground so it doesn't fall too far).

Also, the large rear cap that has to be depressed using a large C clamp (it is spring loaded with a large stiff spring) - when re-installing the large rear cap, the C clamp has to be exactly in the middle of the rear cap so the cap releases straight. I had to push in/release the C clamp a few times to get the cap to sit straight. This process is slightly challenging because the pump is a little heavy and bulky. Having a large vice helps.

Al
Al, interesting point about remove the pulley. I thought of doing that as well, but the puller worked just fine for me, but I took my time and made sure nothing was slipping or bending anyway it shouldn't be.

I meant to snap photos of the C-Clamp process, but I was in a hurry to get that damn seal out. It helps to have a clamp larger than 6". It BARELY fits initially, and it won't work when you try to reassemble.
 

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W201, W212, W221, & W222 Moderator
'84 Euro 500SE, '85 Euro 2.3-16, '51 Euro 170S, '97 Jeep Wrangler Sport, '15 G63 AMG
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Discussion Starter · #10 ·
Excellent tutorial. Thank you.
Thanks for the praise! Hope it really helps some folks out there.

Also, the kit came with a Vickers pump seal as well, so if anyone has need of it, PM and it's yours.
 

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Josh, you never said why you had to do this. Please tell us what symptons/problem you had and what was the outcome after the R&R.

Also, can you recommend a good rap video for my collection?
 

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W201, W212, W221, & W222 Moderator
'84 Euro 500SE, '85 Euro 2.3-16, '51 Euro 170S, '97 Jeep Wrangler Sport, '15 G63 AMG
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8,890 Posts
Discussion Starter · #13 ·
Josh, you never said why you had to do this. Please tell us what symptons/problem you had and what was the outcome after the R&R.

Also, can you recommend a good rap video for my collection?
I will update the OP with this information.

If you want "good", you'll have to settle with this:


There are no good rap videos...

Download a Steve Vai video and be amazed.
No arguments here!
 

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1987 & 1991 C126
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Hi all,

In addition to this good writeup I wish to note:

I would take heed here " after the nut is off, simply hold the pulley perimeter with one hand and hit the shaft end hard with a hammer and the pulley will pop off "

This is REALLY good advice for pulley removal.. No way you can distort the pulley..

I would add here to leave the loosened nut caught by a few threads on the shaft (so as not to drop the affixed component… AND to use a copper / brass hammer on the shaft end instead of steel so as to alleviate any possible damage either the shaft or the fastener.

Thats how I was taught……… always worked for me without subsequent drama..

Cheers, MBL
 

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W201, W212, W221, & W222 Moderator
'84 Euro 500SE, '85 Euro 2.3-16, '51 Euro 170S, '97 Jeep Wrangler Sport, '15 G63 AMG
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8,890 Posts
Discussion Starter · #16 ·
Hi all,

In addition to this good writeup I wish to note:

I would take heed here " after the nut is off, simply hold the pulley perimeter with one hand and hit the shaft end hard with a hammer and the pulley will pop off "

This is REALLY good advice for pulley removal.. No way you can distort the pulley..

I would add here to leave the loosened nut caught by a few threads on the shaft (so as not to drop the affixed component… AND to use a copper / brass hammer on the shaft end instead of steel so as to alleviate any possible damage either the shaft or the fastener.

Thats how I was taught……… always worked for me without subsequent drama..

Cheers, MBL
That's actually a good technique as well; the nut catches the pump basically.

If you use the puller, just be slow and gentle. Otherwise this is another way of going about doing it.

Should I get my hands on a Vicker's pump, I'll expand this write-up to include both of them. Actually, now that I think about it, the 190E's pump may be a Vickers. I'll look the next time I pull that car apart, but it's pretty much solid so no need to mess with it at the moment.
 

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'91 560SEC, '91 300SE (sold), '98 Yota, '02 S-10 Hauler
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Excellent write up Josh :thumbsup: Where can I get one of those "MB approved milk jugs" :D

I have a Vickers pump but I don't think the front seal is what's leaking, pump side of pulley is bone dry, from diagrams I've seen I think it's the O ring/seal between the pump and the reservior.

I need to get a filter for it too, never had one and I'll have to check to see if anything is missing in there
 

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W201, W212, W221, & W222 Moderator
'84 Euro 500SE, '85 Euro 2.3-16, '51 Euro 170S, '97 Jeep Wrangler Sport, '15 G63 AMG
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8,890 Posts
Discussion Starter · #18 ·
Excellent write up Josh :thumbsup: Where can I get one of those "MB approved milk jugs" :D
SAM's Club :eek:

I have a Vickers pump but I don't think the front seal is what's leaking, pump side of pulley is bone dry, from diagrams I've seen I think it's the O ring/seal between the pump and the reservior.

I need to get a filter for it too, never had one and I'll have to check to see if anything is missing in there
That sounds like one of the internal O-rings then. If you pull it, you might as well do the front seal along with it. It's likely old and living on borrowed time. No sense in pulling the thing twice!!

Also, the steering is responding well, no leaks, and I'm a happy camper!!

Check behind those pulley's folks, and check the AC Compressor power line as well. If it's soaked, you've got a front seal leak!!
 
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78 280S, 81 300SD, 82 300D, 92 300E 2.6, 90 260SE, 94 S280, 10 E300,
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My P/S pump has just been rebuilt also, I was surprised that it took only around 30 minutes although it was done by a pro, I was watching the whole time. Mine had a Vickers pump, but the procedure is basically the same.
 

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'91 560SEC, '91 300SE (sold), '98 Yota, '02 S-10 Hauler
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I know you did a ZF pump, does anyone have a good diagram for a non tandem Vickers pump for a '91 300SE ? I got my seal kit in today :thumbsup:
 
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