Unlike when I did this job on the 560SEL back in 2021, the genuine upper control arms are now NLA.   This this job is all labour time, I was quite deliberate with the parts I chose.   I would have used the genuine upper control arms had they been available.  Since they were not, I went with TRW.

The parts I ordered from Pelican Parts were as follows:

• Upper control arm – left: 126 330 06 07 (TRW)
• Upper control arm – right: 126 330 07 07 (TRW)
• Lower control arm ball joint x2: 116 333 09 27 (Genuine)
• Control arm bushing (upper outer) x2: 116 333 40 14 (Rein)
• Control arm bushing kit (lower outer) x2: 123 330 14 75 (Febi)
• Control arm Bushing kit: 126 330 00 75 (Lemforder)
• Front Shocks: 126 330 08 30 (Bilstein B4)

However, when I got them, I found they had substituted 116 333 40 14 and 123 330 14 75 with Uro parts and not told me.   Uro is not a brand I will use unless I have no other choice, so I had to order those parts again from another supplier!  This is hugely frustrating as Pelican could have notified me of this.

The feedback I had from the job was that these parts had been on the car for a long time, certainly during its time in the UK.   From the outside they looked ok, but the various bushes were corroded internally.  As the car was imported between 2004 and 2005, they were well due to be changed.

The car also needed a wheel bearing along the way.   The front suspension feels a whole lot better, although I am still getting that vibration during steering, which must be related to something else.

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I obviously couldn’t drive the car in this condition.  Not only would it be dangerous with the odd power steering, but without a water pump I would cook the engine in short order.  I put the car back in the garage and then booked it in with my mechanic for March, as I was about to head overseas for work.

On the day the car was due in, I got up very early to call road service to get a tow.  I figured the wait would be shorter if I called before 6AM.   Turned out it would only be about 90 minutes, which wasn’t too bad.  And since the car could be driven short distances, I would be able to get it out onto the road for them.

When they were about 20 minutes out, I went to start the car and move it out onto the road.  I should have put the car on the trickle charger.  Having not used it properly since December, and then starting it in January without a working alternator had the battery flat.  Luckily, the 240D came to the rescue.   The 55 amp alternator on the 240D doesn’t sound all that big, but with everything turned off, the 240D doesn’t consume any power to run, so it soon had enough charging current through the jump leads to start up the 560SEC and get it out onto the road.

The tow up to the workshop went without incident and I followed in the 240D.   Being on a tow truck is probably the only time a ECE 560 is slower than a 240!

A couple of days later, I had a call with the diagnosis of the problem.  The M117 crank pully assembly bolts onto the end of the crankshaft.   It is made up of three pieces.   There is a hub (17) that goes over the end of the crankshaft (5) and is held in place with a woodruff key (11).  The harmonic balancer (26) and the actual pully (29) is bolted onto this hub.  Then the whole thing is torqued down to a high torque value.

For some reason, my pully was not on very tight.  I can only assume that in the past, somebody has changed the front crank seal and not torqued it up properly.  It’s never been off in the six years I’ve owned the car.

Not being tight enough had put too much pressure on the woodruff key, and it had been destroyed.  A combination of being beaten up and then melted.   The hub had cracked and there was wear to both the inside of the hub and the end of the crankshaft.

The ‘correct’ repair would be to replace the crankshaft, woodruff key and hub.  Neither my mechanic or I were very keen on this repair.

I sourced a good used hub, and my mechanic further disassembled the area to have room to work.   This involved removing the radiator, condenser, a/c compressor etc.   He then called in the guy who does his thread repairs to help.

The solution they came up with is something that is done regularly on American V8s when they want to add a supercharger.  In this application, the supercharger puts too much pressure on the crank and woodruff key, so they drill in and add a pin that holds it all in place.   This is a far stronger solution than the woodruff key.  The downside is the pin must be drilled out to replace the front crank seal.   We put a new seal in as part of the assembly.  He also had to make up a bracket to drill straight in.

After that everything had to be put back in place and the A/C gassed up.  Its great to have the car back.  It has always been a great car to drive.  The extra power of the ECE engine makes quite a difference.

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Back in 2020, I had a similar issue on my 560SEL and changing the viscous fan coupling fixed it.    Back in 2020 I used a Behr/Hella coupling and paid USD$160 plus shipping.   The Behr/Hella coupling was made in China and a fairly different design from the original Fichel & Sachs unit.   So far it is still working well on the 560SEL.   However this part has now been discontinued so it wasn’t an option.

The part number for my car is 116 200 11 22.   It looked like I had four options.   I could get HT (Hamburg-Technic) for about USD$80; URO Parts for about USD$110; Meyle for about USD$140 or Genuine MB for about USD$550.

None of these options were great.  I had never heard of HT, URO is a brand I try to avoid unless there is no other option at all, and Meyle is also a brand I avoid, but prefer it to URO.     I’ve read of pretty high failure rates for cheap viscous fan couplings.   Mostly these failures were the coupling no longer cooling well, but I found a couple where it had locked on and caused other issues.  Genuine was less likely to have these issues, but USD$550 plus shipping is going to up towards $1000.

After debating the way to go in my head for a few days, I noticed that the Genuine had gone on sale at FCP Euro for $395.   Still expensive, but much more realistic.  I bought one.

Today I went to fit it.  Its a very easy job on the W126.   I spent far longer researching clutch brands than fitting the new one.   Unlike the Behr/Hella unit from 2020, the genuine part looked identical to the original.   It was made in Germany by Horton rather than Fichtel & Sachs.   It was manufactured in 2014, which makes me wonder if this part will go NLA after current stock runs out.

The viscous fan coupling is attached to the pully with four 10mm bolts.   They are quite easy to remove with a long spanner.   To get enough clearance to remove the fan assembly, the radiator shroud should be loosened.   It does not need to be removed.   I normally remove the three bolts closest to the top and leave the bottom one unscrewed but not removed.   This makes installing the new coupling easier.

Once the fan unit is out, there are also four 10mm bolts holding the viscous coupling to the fan.   Plus my original fan coupling was stuck to the fan after so many years and needed a few taps with a rubber mallet to get it off.

There really are not any tricks to re-install the new viscous fan coupling.  It just bolts back in like the old one, plus the radiator shroud is re-attached.    I had the whole job done in 30 minutes and I am very slow when working on cars.

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Turns out the new battery I bought along the way was slightly too big.   It was fouling on the bonnet and putting pressure on the hinge.   Since there was nothing wrong with the old battery, I decided to just put that one back in.    In the photo, the one on the right is the new one.    It’s a shame, because the new battery is brand new and a better spec.

The other thing I wanted to fix was the battery tray had some surface rust, and the battery hold downs were missing.   The battery hold downs may seem unimportant, but they prevent the battery shorting out on the bonnet or moving around over bumps or heavy cornering.   They were also missing on my 560SEL.

I’ve previously repaired the battery trays on both my 450SLC and 560SEL.   In both cases I used a rattle can primer and then top coat.    I wasn’t especially happy with the result on either car.   On the 450SLC, the top coat was too thick and ended up being soft.    On the 560SEL I did two thin coats, and it was better, but the trays are not uniform and it was hard to get even coverage.   I thought I would try something different this time.

As before, I started with a wire wheel attachment for my drill to remove surface rust.  I also used some brake clean to get some grease and residue off the tray.    Surprisingly, the tray in the 560SEC was better than the one in the 560SEL.    After a go with the wire brush, it actually came up reasonably well.

The bottom was even better, the only real rust around where the ‘tongue’ attaches to the main body of the tray.   I still thought there was value in doing this side regardless.

Instead of the rattle can, I decided this time to apply specific rust epoxy paint with a brush.   This would result in a worse finish, but a much better application of the paint.    Since the battery tray is really not visible with the battery installed, I thought this was a decent trade off.

I did two coats on the top and one on the bottom.   My nine year old daughter enjoyed painting the 560SEC battery tray.

I probably could have even used a product like miracle paint and had a better finish, but I didn’t have any, nor the time to drive to the supplier and get some.   After two coats, the 560SEC battery tray looked quite a lot better, but it was of course obvious the paint had been applied with a brush.

I’ll see how it looks when I remove the battery next time.    There is certainly a lot better all around coverage of the paint.

While the battery tray was out, I vacuumed all the leaves out from underneath it.   It is worth removing the battery tray every few years to remove any dirt and leaves from this part of the car.    Getting the 560SEC battery tray back in the car was a bit fiddly, it was hard to get all three holes to line up.

In the end I had the tray in and it was a huge improvement to before.  It’s still obvious it was painted with a brush, but there is no longer any rust or detritus.

Final step was to re-install the battery.   While I was there, I installed a battery hold down.   I had a couple on hand, a very rusty one from the 420SEL parts car, and a reasonable one that I found in the boot of the 560SEL after I ordered new ones.

I’m not sure what I am going to do with that big Delkor battery. Off the top of my head, I don’t think it fits any car I have. I may try and sell it. It wasn’t cheap, but it did get me home.

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Changing the rears in the second generation W126 is a bit more of a fiddly job.   For starters the factory grilles are now very brittle.   Not only are they over 35 years old, but the Australian sun is not kind to plastics.   It is quite common for them to break when removed.   The best way to ensure this does not happen is to remove the seats first.    The grilles have to slide towards the front of the car, and the top of the rear seat is in the way of that.

Despite having owned three 560SEC’s in my life, I had never removed the rear seat.  I assumed it was like the C107 or W111 coupe, where getting the rear seat out is like wrestling with a gorilla.   However, that is not the case in the SEC.   The left and right sections are removed separately, making it quite easy to get them out.   As with the saloon, the bottom cushion is removed by pressing the red tabs, and then the backrest lifts off ‘hooks’.   It took me a matter of minutes to get the seats out.

While they were out, it was a good opportunity to clean them and apply leather conditioner.   While I regularly clean and condition the seats in the car, it was amazing how much better a job I could do having them out.   It was almost worth doing this job just to force me to remove the seats and clean them.

Once the seats were out, the speaker grilles could be removed.   They slide towards the front of the car.  It is vital to be very gentle with them.  There are various hooks that are easily broken off.   The hardest one to get out is actually the front one.   Normally what happens is that it also pulls out its receptacle from the parcel shelf.

Once I got the grilles out, I was shocked to find that the car still had the original factory speakers.   Still with the original MB part number on them, made in West Germany.   They sounded better than the more modern Pioneers I removed from the front.    It seems incredible that somebody would go to the trouble of rewiring the car for the speakers, fit new front speakers, fit a new head unit and leave the old rear speakers alone.   As the car had been rewired to remove the fader, the becker plus were no longer there.

The series 1 W126 had the same size speakers front and rear.  To fit larger speakers in the series 2 cars, the factory came up with these angled brackets to fit a 16.5cm speaker.   The brackets are held in with two screws towards the front of the car.  Once those are out, the unit pulls towards the front of the car and can be lifted out.

The factory speakers are glued to that bracket.  Given their age, its fairly easy to pry them off the brackets with a screwdriver.    Instead of gluing my new W126 rear speakers on, I used double sided tape.

The Crunch speakers fit perfectly in the brackets.   The speaker is actually deeper than the bracket, but that is ok, as there is a hole in the rear parcel shelf for them to protrude through.

Once mounted, the Crunch speakers are slightly taller than the old factory ones were.  They still fit into the hole in the parcel shelf and the factory cover still fits on there quite well.

In the picture above, you’ll see the square hole in the parcel sheft to the front of the speaker.  A receptacle for one of the hooks in the speaker grille goes in there.   In both cases for me, the receptacle came off with the grille.   It is much easier to fit the grille if you remove the receptacle from the grille and put it back where it goes.    I found this out when doing the second speaker.

But before I put the grilles on I tested the quality of the sound, and I was happy with it.   Its not perfect, but its a huge improvement on what I had before.   I feel like I have a system that looks like a factory setup, but sounds better.  I also have much nicer and cleaner rear seats.    I’ll have a long road trip to decide how good this system really is.

In testing the setup, It also sounds heaps better if the EQ function on the iPhone is disabled.

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A drive like this meant attending to a few things I had on my to do list for the car.   One of them was to replace the W126 drag link.   It was supposed to be replaced at the same time as the tie rods and idler bushing were done.  Unfortunately, I had bought the wrong part.   I should have realized but the left hand drive part is different to the right hand drive part.    The part number for the RHD drag link is 126 460 09 05.

The other thing I wanted to do was check the balance of my front wheels, as I had a wobble on the way down to Canberra for the ACT concours.     I figured it made sense to do the drag link first, then send the car in for an alignment and to check the wheel balance.

The drag link is quite an easy job to do with a hoist and the tool to pop off the ball joints.

As it turns out, this would be the last job I would do on the hoist for now.   Once I finished it, I started putting the 300TE and noticed a growing puddle of hydraulic fluid on the ground.   I quickly got the car down.   I’ll need to get the hoist serviced.

With the new W126 drag link in, the groaning/vibration I was getting from the steering at low speed was almost completely gone.   The old drag link looked like it had been on for a long time.   Certainly the tie rods were probably from the car’s time in the UK, as the bolts were rusty.

I took the car to the alignment shop.  They found it was quite badly out of alignment, and that the front wheels didn’t have enough weight on them.   I haven’t been onto a motorway since, but a short burst of speed made the car feel a lot better.

The other thing I di while I was working on the car was fit a BM2 Battery Monitor.   I’ve got these on a few other cars.  It allows me to monitor the health of the battery from bluetooth.

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I am also doing a similar project on my 300TE.   On that car, one of the front speakers is damaged and makes a rattling sound.    The W124 speakers are harder to find than for the W126.  The front speakers on a W124 use an odd mounting system, and the rears have minimal clearance.    There was an audio store in Germany that sold a kit for the S124, and also carried speakers that should fit into the second generation W126.  It made sense to buy them all at once, as shipping from Germany is very expensive these days.

Based on that, I ordered four sets.    I prefer to keep all four speakers from the same manufacturer (and ideally the same range) in a car.

The speakers for the W126 were 10x15cm for the front and 16.5cm at the rear.   The factory front speaker in the W126 is actually a small round speaker in an oval housing.  These can be replaced by oval speakers.    They also came with adaptors for the Becker plug system.

When I removed the grilles in the 560SEC, I found a set of old Pioneer 4×6″ speakers in there.   They looked like they were about 20 years old or so.   The Becker plugs were long gone, so it was quite easy to use the standard speaker plugs for the new crunch speakers.    On comparing them, the Crunch speakers had a far larger magnet, and it was quite a tight fit to get that magnet through the speaker opening.    The speakers don’t sit quite flush due to the large magnet size, but there is just enough room to install the speaker and cover it with the factory grille.

The new speakers sound a lot better.  It’s never going to be perfect as I’m playing music through an FM transmitter, but they do make a big difference.  On the 560SEC, I am using a Becker 1402, coupled with the factory line out module to use an external amplifier.

Next step is the rears, which are far more fiddly to install on the W126.

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The fluid in the 560SEC looked fairly dark.  I last flushed it in 2019.   It seemed to take on this colour once the system was finally working properly.   In a previous article I outlined how a previous mechanic had the SLS lines reversed.   This resulted in low ride height.   I guess this was preventing flow, and therefore once things were flowing properly, any leftover debris in the system came through the fluid.   The picture above shows the old fluid.

I’ve covered the procedure for a W126 self-levelling rear suspension flush before, and it really is very simple.    The first step is to remove all the old fluid from the reservoir, and top up with clean fluid.

From there, I attached a clear hose from the return and put the end of that hose into a container.   In this case I used an old snow foam container.    Once this is ready I started the car and let the dirty fluid collect in the container.   The flow is low, so this job can easily be done with one person.

I also checked the filter.   It was a bit dirty so I changed it, and I’ll get a new filter for the 300TE.   Having a lot of debris in the system can mean a dead sphere.  I’ve driven a car with dead sphere and its really noticeable.    It doesn’t seem like one of my spheres is dead.

Once I saw clean fluid coming out as part of the flush, I turned off the car and then topped the reservoir up again.    Doing a w126 self-levelling rear suspension flush is a good simple job that is easy to do at home. The final photo shows the job complete and the reservoir topped up. ZH-M is clear, so the colour of the fluid should reflect that.

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I didn’t really like driving it in reverse with that resistance.  I used to make sure I parked the car so I didn’t need to reverse it when cold.   This wasn’t a long term solution.   I am planning to drive the car to Melbourne later this year, so I didn’t want the transmission to fail on me on the trip.   In addition, was worried about damaging things further driving it this way.   At this point I thought it was time to have the 722.3 transmission rebuilt.

This was not a job I wanted to take on myself, so one of the mechanics I use arranged to take the car over to a specialist he uses for these transmissions.    I got the car back earlier this week and its nice to have it shifting so nicely and to have reverse again.

When having a 722.3 transmission rebuilt, its possible to just have it resealed, or actually go through the whole thing.   As my issues were deeper than just leaks, I wanted it done properly.   The labour to remove, tear down, re-assemble and re-install the transmission is the lions share of the job, and I didn’t want to have to do this any time soon.  I also asked them to replace the rear main seal while the transmission was out.

The rebuilder left the old parts for me to examine.  I’m not especially knowledgeable about the inner workings of these transmissions, so I wasn’t familiar with all the parts that were replaced, but it was interesting to see the major ones.

From what I understand, the picture above shows the friction discs.  The set at the top is for the reverse clutch pack and the bottom ones are for the front and rear clutch packs (note there are two different sizes).

As expected, the reverse friction discs are far more worn than the others.   It’s good to see that while they were worn, they were not down to metal.

The front (left) and rear (right) bands were also replaced as part of the rebuild.   Like the friction discs, there is clearly wear, but they don’t seem badly damaged.

There were also other misc parts replaced, such as the vacuum modulator and various larger seals.   I’m not sure what the springs and components in the bottom right are for.

Looking at this last photo, it is pretty clear why these transmissions are always leaking.   There are a huge number of o-rings.   Not all of them are for externally sealing the transmission, but plenty are.   There are also these large seals, which I think are for the valve body.  The torque converter was sent away to be rebuilt, so I don’t have any parts to look at for it.

I’ve only driven the car a short distance since having the 722.3 transmission rebuilt.   So far, I’m quite happy.    I’m going to drive the car to Canberra in a couple of weeks as a bit of a trial for the longer trip to Melbourne.   I did a similar thing with my 450SLC before driving it to Adelaide, and the longer drive identified a number of things I was pleased to sort out.

My 300TE had its 722.3 transmission rebuilt not long before my purchase.  Looking at the invoice, there were a lot of the same problems.   Worn reverse clutch discs, and B1 band.   These seem like the standard 722.3 issues.

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At this point a lot of workshops would suggest to rip out the system.   This is a really bad idea.   The self-leveling rear suspension is a simple system that works really well.   Most problems can be simply fixed and are generally cheaper than ripping out the system.   Factory SLS cars never ride properly once the system is removed as the rear springs are always wrong.   The SLS springs are very soft and not suitable for regular shocks.   The replacement springs most use are too hard and cause the cars to ride badly.   The factory was very careful to select the right springs for each car based on the options selected.   For example, a car with a sunroof might have different rear springs than one without.   There is a system of points you add up that determines which springs and spring pads should be used.

As I wasn’t able to fix the system with the normal adjustments, I took the car to my mechanic who is very experienced with it.   Initial tests showed poor fluid flow to the valve, and then even worse flow to the struts.    Based on that I ordered a rebuild kit for the pump from Mercedes Source and a brand new valve.   The post 1986 cars use a smaller valve that I do not believe is rebuildable.   The earlier square valve is.     It looked like the pump was not making enough pressure, and the valve worn internally.   Changing these should fix my W126 Self Leveling rear suspension low ride height.

This valve originally had a W124 part number.   Later, it was superseded to a W202 part number (A202 320 02 58).   Funnily enough, when I got the valve, it had the 202 part number on the box but the W124 part on the valve itself.   The valve wasn’t cheap, but it is still available.   In some ways I’m glad to be replacing it while it is.   I suspect this part will go NLA in the next couple of years.

Fitting these parts meant there was now good flow of fluid to the rear of the car, but not to the struts/spheres.    The new rebuilt pump also showed up a small leak in the high pressure hose that was sent away to be rebuilt.

Checking the lines carefully highlighted the final problem – and it was the work of a previous owner or mechanic.    At some point the hydraulic lines had be cut near the subframe.   They had been joined together, but the two lines reversed.   I’m not sure why these lines would have been cut.  Perhaps the subframe was removed at some point.   In any case, with the supply and return lines reversed, the system never worked very well.  Its surprising it worked as well as it did.

With the lines now properly configured, the ride height is set correctly and the car rides much better than before.   My W126 Self Leveling rear suspension low ride height problem is solved and the SLS should be good for years to come, other than the normal sphere replacement.

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