Pictorial: Steering Box R&R and Engine Mounts - Mercedes-Benz Forum
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post #1 of 21 (permalink) Old 04-20-2013, 08:41 PM Thread Starter
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Pictorial: Steering Box R&R and Engine Mounts

Hopefully my adventure and this thread on replacing the steering box and engine mounts will be helpful for other owners.

My car is a '91 560SEC with 156,020 miles

There has been at least one really solid thread on replacing the steering box by member foolio2 which was an excellent reference.

I agonized for weeks and weeks on replacing both the steering box and the engine mounts but it was not too bad once you get into it and mostly mind over matter and if anything just VERY time consuming. It took me two weekends to complete everything. On a difficulty level I would rate it at 6-7/10.

The main reason for the steering box replacement was due to the loose, vague feel of the steering on my car coupled with power steering fluid leaks, which leaks are a major vice for me.

The engine mounts on my car were collapsed so they were very due for replacement.

Specialized tools required:
1) 36mm Socket (1/2" drive)
2) Impact Gun
3) Puller
4) Steering Gearbox Centering Pin (MB Part No:116 589 06 21 00)

Step 1:
Remove all the power steering fluid from the reservoir, I used a rubber tube I had lying around and sucked it into the tube which I then emptied into a gallon jug. Careful not to swallow any!

Getting started:


Suction Tools:


All the oil sucked out with the top of the power steering filter visible:


Carefully remove the 10mm bolt and the spring and plastic collar combo to get the filter out:


All removed:


Step 2:

I then centered the steering wheel by using a ratcheted harness strap from the wheel to the brake pedal and cloths to make sure the leather on the wheel was not damaged. To remove the steering box will require wiggling the splined shaft to the steering coupling, so it is essential to keep the geometry perfect. I also extended the steering wheel as far outward as possible and removed the key to lock the wheel.



I then jacked the car up, removed the passenger side wheel and placed the car on jack stands. Now time to see how bad the steering box is:


(pretty bad, worn and very wet with leaking fluid)


Step 3:

I removed one of the 10mm bolts holding the exhaust shield and bent the shield out of the way to access the steering coupling.

I then used my impact gun on the steering coupling allen head bolt as this bolt has Loctite from the factory and was worried about rounding the inside of the bolt by using hand tools. Naturally it came out easily with the impact. I then pried the coupling open with a large screw driver and sprayed some PB Blaster on the splines.


Step 4:

Time to remove the high pressure feed and return lines to the steering box. Even though I have line wrenches designed specifically for this task, open ended wrenches would work equally as well. One of the lines came free with no problem, the other one was unfortunately stubborn and corroded / welded to the fitting on the steering box and even though I tried to save it, it ended up twisting and becoming permanently damaged.



After a few choice curse words due to the damaged power steering line, I gathered my thoughts and removed the other end of this damaged line at the pump, which required a 17mm crow's foot socket (3/8" drive) and a bracket on the inner fender (which was tricky to access).

Step 5:
Time to remove the 36mm bolt on the Pitman arm, which came out without any issue using my Impact Gun. Although sourcing the 36mm socket took a couple of hours and a visits to several Tools and Auto stores.



Note the alignment of the Pitman Arm and the spline shaft on the steering box - very important!



I then used my very strong Craftsman puller to remove the Pitman Arm:


In the above picture you can see how wet everything is due to the leaking steering box.

I did heat the Pitman arm with a bit of MAPP Gas before it broke free.

The steering box is ready to come out and I loosely threaded the 36mm nut back on the Pitarm to catch the box once I removed the three 17mm bolts securing the box to the chassis of the car (accessible on the left side fender well)


Note: The steering box is heavy 30lbs so you don't want that dropping on your head as you remove it!

Old 156K box (right) next to the rebuilt CM box that I bought from AutohausAZ.






AutohausAZ gives you $450 for the old core, so I have to make sure and send that bad boy back pronto.

Note that the feed and return line fittings have to be transferred to the new / rebuilt box. I also bought new copper crush washers (MB Part Numbers 007603016401 and 007603012405).

New parts waiting to be installed including the new OEM engine mounts and Stabilus engine shocks:


The part number for the new hose (to replace the one that was damaged) 1264660381







Step 6:

Getting ready to install the self centering tool in the new steering box:


Installed:


I also cleaned the surface rust off the shanks from 17mm bolts that secure the steering box to the chassis and applied graphite anti-seize:




New steering box installed and the splines greased:


As I am stickler (maybe fanatical) when it comes to fasteners and very careful to examine each one upon removal in detail in this case I did not re-use the allen bolt for the steering coupling and purchased a new one (MB Part No:2029902101), note it comes with Loctite from the factory! Having one of these back out on you while driving would be fatal.

Everything else is the reverse of the removal for re-connection, playing special care to line up the hash marks on the Pitman Arm and the spline on the new Box and carefully tighten up the power steering hoses and fittings. The 17mm bolts holding the steering box to the chassis is torqued to 52ft.lbs.

I used genuine MB power steering fluid (about 1.5 qts required) and a MB power steering filter (Part No: 0004662104):

Last edited by slownrusty; 04-21-2013 at 08:35 AM.
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post #2 of 21 (permalink) Old 04-20-2013, 08:42 PM Thread Starter
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OK...so Chapter 2 while I was under my car replacing the steering box, I noticed the engine mounts were collapsed, so decided to change them also.

I decided to support my engine with my 2 ton engine hoist rather than place a piece of wood under the the oil pan (which it seems like several members have done) and lift it as high as it could go:


The engine mount allen bolt that you access from under the car was seized and I could not break it free with my Impact Gun no matter how long I tried. As such I decided to remove the engine mounts from the block by removing the 4x13mm bolts:


Removed with the broken mount:


The engine shocks were stubborn due to the nylon on the bolts and required that I cut the lower bolts with a cutting wheel on a Dremel.

The right side engine mount was trickier to access due to the oil filter housing in the way and also a harness that is actually mounted to the top of the engine mount with a shallow shank 17mm bolt:



Note the damage to the engine mount (red arrow)

Once I had the mounts out, I was able to finally remove the upside allen bolt which I did not re-use and replaced with a better quality and stronger Grade 12.9 bolt:


I also did not reuse the allen bolts that secure the engine mounts to the cross member, I bought a set of stronger grade M8x1.25 ARP bolts with a regular Hex head which will be easier to access in the future and no worries of crud falling into the allen opening:



Engine Mount assembled and ready to be re-installed, I bought OEM Mounts (Part No: 1232413013):



The car now drives much better and smoother. The steering is more progressive and not loose (wandering) and vague as before.

Cheers - Yasin

Last edited by slownrusty; 04-21-2013 at 08:35 AM.
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post #3 of 21 (permalink) Old 04-21-2013, 06:09 AM
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Very good Yasin! Cant wait to come to your place now since you are so experienced with this!

Did you install ElRojo's rear bar yet? I might tackle that today if I have time. Any snags with yur install of the bar?


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post #4 of 21 (permalink) Old 04-21-2013, 07:01 AM
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A splendid contribution! Haven't seen a well-supplemented writeup like this a quite a while, and unfortunately several of those are now missing the photo links (like mclare's great water pump & door handle write-ups).

Thanks for taking the extra time & effort to document your "adventure".
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post #5 of 21 (permalink) Old 04-21-2013, 07:13 AM Thread Starter
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Quote:
Originally Posted by 281lxm View Post
Very good Yasin! Cant wait to come to your place now since you are so experienced with this!

Did you install ElRojo's rear bar yet? I might tackle that today if I have time. Any snags with yur install of the bar?
Thanks! You are welcome to come down anytime. The sway bar is pretty high on the list, but have not had the time to get to it just yet, probably in the next week or two.

Quote:
Originally Posted by MrBits View Post
A splendid contribution! Haven't seen a well-supplemented writeup like this a quite a while, and unfortunately several of those are now missing the photo links (like mclare's great water pump & door handle write-ups).

Thanks for taking the extra time & effort to document your "adventure".
Thank-you! I appreciate it.
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post #6 of 21 (permalink) Old 04-21-2013, 07:36 AM
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Nice write up. I'll be doing the steering box on one of my W124s very soon and your pictures are helpful. Thank you!


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post #7 of 21 (permalink) Old 04-21-2013, 09:33 AM
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Great write up! Thanks for taking the time to do such a thorough pictorial DIY.
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post #8 of 21 (permalink) Old 04-21-2013, 10:13 AM
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Great job. Great pics. I'm super jealous though bc I feel like I might have stripped the hex hole on the passenger interior side mount yesterday. I am hoping its superficial and if I try to get the bit to seat better I can still remove it.

Did you use any creative tools to get the mounts out?
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post #9 of 21 (permalink) Old 04-21-2013, 12:05 PM Thread Starter
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Thanks guys! I appreciate it.

Quote:
Originally Posted by MB_Mike View Post
Great job. Great pics. I'm super jealous though bc I feel like I might have stripped the hex hole on the passenger interior side mount yesterday. I am hoping its superficial and if I try to get the bit to seat better I can still remove it.

Did you use any creative tools to get the mounts out?
Mike - I did not use any creative tools to remove the old mounts, just get the engine as high as possible and slide them out once you remove the 4x13mm bolts from the block.

If you think you may have stripped one of the M8x1.25 bolts, see if you can back it out and replace it with a hex head bolt and I strongly recommend using anti-seize / graphite on the threads. Where possible I always chase the threads with a tap as well.

Regards - Yasin
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post #10 of 21 (permalink) Old 04-21-2013, 12:13 PM
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It was one of the top m6, the one closest to the engine. I removed the m8 and the outside m6. Engine is up pretty high, removed shock and the 4 bolts that attach to the block but that last one is really hard to get at.
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