[Steve_B]

In early February 2015, I saw an ad for a car for sale, and could not sleep for two nights.

It may have been a moment of weakness, or mid-life crisis struck me suddenly, but I could not bear the thought that a beauty like her — a very early-built C140 with a V12 (rolled out from the assembly line in the second half of 1992, US model year 1993 — the only year the C140 would wear a badge 600SEC), with low miles (50K), and a binder full of receipts from SoCal dealers and independent shops, would be parted out.

Why? According to the seller — the car needed MAJOR transmission work — a “slow reverse” had become “no reverse” and finally, the 722.362 transmission chewed itself.

The car was 100% original (meaning that everything in the engine bay was last touched during the assembly process, including the harnesses). Had passed CA smog test every year for the last 4 years.

Well, after I presented a series of carefully thought-out arguments, my better-half felt assured that I won’t spend the kids’ college money on a car, and reluctantly gave me a carte-blanche to proceed.

The rest is history. A couple of days later, I pulled the trigger and fulfilled a dream I have had since I was a teenager - I now owned the very car, the picture of which was on a poster above my bed some 25 years ago.

Those that have seen my posts will recall that I am not a mechanic, have a full time job teaching at a local college, have two young kids, and have very little time to play with toys for big boys. I also must add that up until that point, I have not owned any other MB product.

The car came from California on a transporter (I am on the East Coast - all dealings were done remotely, via power of attorney) about 10 days later, and our journey begun. It has been mostly wrenching on my part, and sadly, no driving. The car still has CA tags (now expired of course) and I must also admit — there is still CA gas in the tank.

The 1st project was the transmission. The full ordeal is documented here. Took me almost 1 year to take it apart and put it back together. Lots of reading, bought lots of tools. Learning curve was very steep.

Unfortunately, after the transmission was removed, I discovered an external leak from the head-gasket. No overheating - corrosion and lack of proper maintenance were the culprit, as documented here.

Splitting the engine and getting everything back-together was very hard, many more hours of reading and in the garage.

Along the way, I also addressed starter, engine mounts, prop-shaft bearing support, and a couple of other issues.

8 months ago, the engine roared again. The car was moved on its own power and I had a victory lap on the streets o my neighborhood. The box was shifting smooth, the engine was running well.

Then, I took a break and traveled far East. When I came back, I did some more fiddling and came to the realization that we’re not ready for tags — the suspension in the rear needed attention, the suspected leak from the differential output shaft seal seem to be worsening.

It was time for more work.

So, after this long introduction, here we go.
The contents will be broken into several parts for easier navigation. Please follow along and enjoy reading about my recent "adventures"
Not interested in all the technical parts, then please fast forward to my final words in post #18, as I anticipated there will be some ensuing discussion.

 

[Steve_B]

Part 1. Draining the SLS system and servicing the accumulators.

I will let the pictures speak for themselves. To gain access to the left accumulator sphere on the driver side (LHD car), the rear part of the exhaust had to come out. Not too difficult if you have a helper, but for a single person on their back — it is painful. The exhaust is HEAVY.

 

[Steve_B]

Part 2. The SLS shocks.

As expected, the shock mounts and the lower bushings were past their prime. New bushings were made and fitted following this lead:

http://www.benzworld.org/forums/w140-s-class/2635090-my-solution-replacement-lower-sls-joint.html

I also provided a picture of what the infamous shock mount looked inside. The picture is somewhat misleading. The rubber was rock-hard and would easily crumble:

http://www.benzworld.org/forums/w140-s-class/2588409-accumulators-change-not-change.html

 

[Steve_B]

Part 3. Lower control arm bushings.

With the shocks removed, I could clearly see that the outer bushings were in need of replacement. To do outer only, or do both?
The inner ones were probably OK, but I decided to remove the control arm and do it all. The control arm removal called for compressing the springs, but since I was going to remove the half-axles to gain access to the differential output shaft seal (please see part 4d), there was more room to move about and I felt I’ve got to do it right.
Warning: If you don’t order parts from the dealer, some online catalogs for aftermarket parts, TWR in particular, have it wrong — TRW 2013528865 does not fit, as discussed in an earlier thread.

Pictures of the TRW bushing as compared to the OEM here:
http://www.benzworld.org/forums/w14...numbers-suspension-bushings.html#post15503273

 

[Steve_B]

Part 4. Differential.

Attached is the parts diagram.

The seal is #95. One might as well do the rubber O-ring (part #80) while there. Sound simple enough, but to gain access to those two, the half-axle has to be removed from the flange (6 bolts which require HZN bit and the ability to rotate the axle. The car has to be in neutral, while you are under it (RECALL that the axle has to be rotated, so the parking brake cannot be engaged!)

Also note that the bolts in question and torqued in the assembly process with thread locker, so using long extensions and doing the job from the fender-well is tricky. The risk of stripping the fasteners is very high, be careful.

Anyhow, this is challenge #1. If you succeed, the flange will look like what is on the attached picture.

Challenge #2 follows, and be forewarned, it is MUCH bigger.

 

[Steve_B]

Part 4a. Differential cover removal.

The output shaft has a c-clip, which needs to be pulled in order for the output shaft to come out. To remove the c-clip, one must remove the differential cover. Part #173 on the diagram. 8 bolts which also require HZN bit. But to get to them, the rear differential support (part #179) also needs removed. This job is a BEAR. There are 6 bolts in total. Two secure the brace to the subframe (via the rear differential support bushings) and four bolt onto the differential cover plate. Access to some of those is EXTREMELY difficult.

I absolutely hated the two top ones — no room for finger, let alone a socket.

 

[Steve_B]

Part 4b. Rear differential support on the right - interference w/ the spare wheel wel

The MOST difficult job was wrestling with the last bolt, the one that keeps the brace attached to the subframe via the differential support bushing on the right side. The picture needs no words. The bolt is #182 on the parts diagram

.

On one side is the spare wheel well, on the other - the accumulator sphere and the ADS module. Even with those out of the way, putting any wrench there is very hard.

 

[oefvetw124lover]

great stuff,keep up the awesome work

 

[Steve_B]

Part 4c. Finally, the c-clip is visible.

After many hours on my back in the cold garage, I finally removed the cover (drained the gear oil first, oh, the smell of 25 year old gear oil is disgusting) and gained access to the c-clip. The excitement was short-lived. Pulling the c-clip is not easy.
The methods you may see online, using a bent coat-hanger or other improvised tools do not work as advertised.

Eventually, after some more time on my back on the garage floor and lots of inappropriate language, the c-clip was out.

But then, the shaft would not move. So, I had to undo the bearing cap bolts and remove everything together.

 

[Steve_B]

Part 4d. Output shaft seal - MB 0149979747.

On the bench, replacing the seal and the O-ring was easy. Those were among the very few dealer-sourced parts I used.
Given the amount of ground-work to get to this point, I decided it is prudent to replace the seal on the other side too. It may not be in near proximity to the exhaust (I think this is the reason why the driver’s side was cooked in a first place), but I was determined not to deal with the work described in Part 4b.

 

[Steve_B]

Part 4e. Bearings.

Call it mission creep if you wish, but I had easy access to the bearings - parts #62 and #101.
Google National 387AS and SKF 6008 - these are what is needed.
New ones fitted and buttoning up can start.

Assembly in the reverse order.

 

[Steve_B]

Part 4f. Rear differential support bushing.

While trying to put the bolt through the support bushing of the differential on the driver’s side, I noticed that the rubber is cracked.
Very likely the culprit again is heat from the exhaust.
Yet another delay, pressing this bushing out and pressing the new one in is a major PITA because there is very little room from the front. VERY, VERY HARD job to do.

Edit: I am attaching the parts diagram so the scope of this job can be envisioned better.

The bushing that was replaced is #11.

 

[Steve_B]

Part 5. Other “mini” projects done while waiting on parts to arrive.

During the downtime, I figured I should inspect/clean/replace the swaybar bushings and links. Surely, the rubber was not in a presentable shape. Not something I otherwise would have done - I believe in “if it is not broken, don’t fix it” - but in this situation, spending an extra hour and $30 to renew old rubber seed justified. Note that the links were dirt-cheap MOOG (closeout deal) and the swaybar bushings were MB, but also surprisingly affordable.

I also replaced the third differential rubber mount (the vertical, two-piece). Used the MB repair kit #29 here:

 

[Steve_B]

Part 6. The parking brake was not properly adjusted.

Since the transmission was in neutral, as a rotation of the axles was needed, I notices a slight rubbing on one side. Sounded like the parking brake was not released completely, even though the release mechanism was in the resting position.

Well, it turned out the parking brake was not adjusted properly, and the brake shoes (records show they were replaced in 2011, less than 5000 miles ago) were gone. But to get access to the parking brake shoes, I had to remove the disks and it was a PITA. The disk on the one side was stuck and took some serious hits with the hammer. As a result, I did replace not only the parking brake shoes, but also installed new rotors and brake pads.

 

[Steve_B]

Part 7. Back to the SLS system. Tandem pump overhaul.

Great thread by G-AMG on the subject:
http://www.benzworld.org/forums/w140-s-class/1481425-photo-diy-steering-pump-overhaul.html

I must add to what I already wrote in post #52 that the pump has to come out.
The repair kit is cheap (ca. $20-25) and if the shaft is not badly damaged, cleaning the components and putting the seals in is relatively easy.

Putting the pump back in is another story. Not fun. I found the MOST difficult part of the whole job to be attaching the high-pressure hose to the pump. Note the banjo bolt with the 2 copper washers (arrows point at them in the picture). Very little room for your fingers and for wiggling the pump.
I ordered 5 washers, just in case. Lucky me — cannot tell you how many times I dropped them. Lost 1, damaged 1.

Note that I also changed all return (low pressure) rubber hoses. They slide over barbed fittings and are secured with hose clamps. The rubber was severely hardened and reusing it probably would have been a mistake. Keeping fingers crossed for dry connections and no weeping.

 

[Steve_B]

Part 8. Steering gear.

My steering gear box seemed fine, no leak, just a tiny little drop would form.
Note that the drop is forming on the bolt, not along the shaft, which suggests that the lip-seal fix discussed here is not going to work for me:

http://www.benzworld.org/forums/w14...ering-gear-box-seal-replacement-question.html

Well, I am happy to report, that the procedure that call for drilling small holes in the lip-seal and removing it with small screws is an overkill. All this work can be done on the bench.

What needs to happen (WITHOUT disturbing the adjustment bolt at all) is the following:

1. Remove the pitman arm. Details in the above-referenced thread.

2. Leave the lip-seal and the snap-ring alone, they will de dealt with later.
The four allen-screws securing the bearing cap will have to be undone. Use good tools. Access is not great and those screws are Loctite-d from the factory (i.e. they are self-locking, I Loctite-d upon installation)

3. Then, again, WITHOUT disturbing the adjustment bolt at all, slide the bearing cap down.
Be prepared to take a shower with old and nasty PS fluid.

4. Take the bearing cap, wash good with brake cleaner. Dry, remove the lip-seal (first is the snap-ring, but doing it on the bench is a breeze). Clean again. Lubricate the new seal and press with a suitable driver. Properly sized socket will work too.

There are two O-rings to be replaced - one large on the bearing cap body, and one tiny one. It will be stuck in groove on the mating surface of the steering gear box and I could not take a good picture of it. Likely this was the culprit and a developing problem. The exhaust down-pipes is close and the poor guy must roast there.

If you have the gearing box overhaul kit, you may also want to replace the teflon seal on the bearing side.

Putting it together is in reverse order. No difficulties. You want to pitman arm back in the EXACT same place, and if you did not mark the original location and measure the distance between the bearing cap and the pitman arm with calipers, you will likely find it impossible... :-(

 

[Steve_B]

Part 9. Moving to the front.

The project is still ongoing. I moved onto the front and after cleaning up some of the mess I made while drawing the SLS and PS reservoirs, I discovered that the front swaybar bushings were done. They are now replaced, but I will also do the swaybar links, as they seem to have some play. Still debating if I should replace the front LCA bushings, as a 4-wheel alignment will be needed anyways...

Also, I am still researching the topic of synthetic vs non-synthetic PS fluid, which was discussed here:

http://www.benzworld.org/forums/w140-s-class/2768033-mb-344-0-spec-fluid-used.html

but not affirmative YES or NO to date :-(

 

[Steve_B]

Part 10. Final notes.

It’s been almost two full years. Lots os fun, lots of sweat, even some tears.
Some of the parts/tools I had purchased before the work started to ramp up in mid-December are shown, I added quite a few more later, and what’s left is now in a box, awaiting a good time for proper disposal.

You can also see what happened to the old jeans I was using to work in the garage.

To end on a somewhat positive note — this car WILL be, one day in not so distant future, the closest to new, EARLY v12 coupe in the US. I am determined to finish it.

And my final words in this post will be an unsolicited advise to those that consider purchasing the range-topping w/c140 cars — there will be at least 5-10 grand in deferred maintenance in every "garage queen" car out there.

Actually, I could argue that the "mint" or "pristine" cars on the market, as dubbed by their sellers, perhaps don't belong to those categories — the market value for the w/c140 is skewed severely towards the lower bottom and the good cars rarely change hands — I’ve looked at the pictures of nearly every S600 car for sale in the US as of the time of this writing, and can spot problem areas in all.

Just for the fun of it, consider this — do you think there will be anyone willing to pay me, for the whole car as is right now, just enough to cover the cost of the parts I’ve replaced already. My labor is not billable... you get the idea, right?

Bottom line: You will not own the car, you’ll have a relationship with it. If this is not what you want, RUN AWAY (I stole this line from Chris Eleuteri (our own Merc-S600 moderator), I hope I won’t be reprimanded for doing so).

Best regards,
Steve

 

[MAVA]

Very nice Steve.. Thank you for sharing..

martin

 

[glepore]

Wow. Will update when my diff arrives.