W211...almost heaven (but not quite)

By far one of the most common cars we get asked for parts for is the venerable W211 E Class. Not because they're particularly unreliable, but because there are just so many around and they are getting to the age of young adult children who just won’t seem to leave home. 

Produced between 2002 and 2009, the W211 got a facelift in 2006 which aside from some cosmetic changes (as pictured above) came with different model designations and engines. 

The most common pre-facelift models, the E320 and E500 have the M112 and M113 engines respectively, which are renowned for their reliability. Aside from the odd water pump, pulley, rocker cover gasket and other common items, these are pretty bulletproof.

The later facelift models the E350 and E550 have the M272 and M273 engines, which are a step up in performance, but were a downgrade in reliability while they went through teething problems (which is a pun you'll get later). Most of this list is dominated by that...

The following are some of the more common enquiries we get about W211s.


SBC Hydraulic Unit

The only hitch in the pre-facelift models up to 2006 isn’t the engines, but the SBC braking system. The SBC braking system uses a microcomputer to monitor the inputs of the driver and the actions of the car in order to distribute pressure to each wheel independently, based on needs. A great step forward in braking technology, except…the control unit was programmed to 300,000 applications before you get a nice warning light on the dashboard...


Better start counting each time your foot goes on that pedal, or better yet, stop braking! While there are other potential causes of failure, like contaminated brake fluid, the magic number seems to be the cause of most of the hydraulic unit issues, which usually means a new hydraulic unit needs to be fitted.

A new SBC hydraulic unit isn't cheap, but it’s the safest way around it. You can reset the count, but to do it ‘well’ takes specialisation. It can be done once safely, twice is pushing it. Further assuming it is just the count, and not a fault with the pump, is risky. Messing around wiping codes can leave you blind as to whether there is actually a fault with the braking system. If the pump is actually failing, you could be caning it down the motorway (at legal speeds) only to see this...

Not ideal if you actually need to stop! 

In the interest of safety, your best bet is to try a second hand pump from a car that’s done low Ks, or failing that, fork out for a new one!


Airmatic - Rear Airbags, Front Shocks, Pumps & Valve Blocks

Many of the more 'luxurious' models of the 2000-2010 period began to be fitted with air suspension - dubbed Airmatic by Mercedes. Not all W211s have Airmatic, but many do. Whilst this system provides an amazingly soft ride and is a real step up from your standard coil overs, they are another complex system in your car and come with potential issues. 

The 4 main components in the system are the front shocks (which come as a complete unit, strut & bag), the rear airbag (separate to shock), the compression pump and the valve block.


Put simply - the bags leak as much air as the guys at Startech on a slow afternoon. This is usually due to degradation of the rubber boot around the bag, leading to tears or holes. 

As the bag leaks, the pump starts thinking 'hey that bag needs more air' so it keeps pumping, and air keeps leaking out. After a while, the pump and the valve block burn out due to constant operation. When the car is off, of course, the pump doesn't inflate the bags and they sag. This is where you get the dash warning lights and a saggy car...










If you catch it early you might need to just replace the faulty bag, but if it goes on too long, the pump and the valve block need to be replaced, which is why rushing to replace a bag without checking the other components can lead to a game of Airmatic musical chairs trying to get to the bottom of the problem. We’ll sell a bag one week, a pump the next and the valve block the week after!


M272 Balance Shaft/Timing Issues

While there's enough to write a novel about, to cut a long story short, the M272 and M273 engines (and the M271 for that matter) have all manner of issues related to the timing, which can become a big problem. Just like confessing you've bought a new Mercedes without your spouse's knowledge, the timing is critical!

If you have a 2004 - 2008 W211 E350, there's a good chance this issue will crop up. There's a serial number cutoff where the parts were upgraded, so if your engine serial is over 2729.. 30 468993, you can skip this bit!

Basically, the teeth on the countershaft wear prematurely due to a defect in the metal hardening. As the teeth wear, the timing chain begins skipping teeth and then elongating. Because they are engineered for precision, even a small amount of ‘stretch’ will throw off the engine timing.  After a while this burns out the tensioner, the camshaft adjusters wear and the guide rails wear. Left unattended this could end in valves colliding with pistons and, just like a Mercedes driver (or anyone for that matter) getting into a BMW, that should never happen!

The parts themselves are fairly pricey, usually adding up to around $1600 to do the whole job. Another half of the cost you'll face is the hours in the workshop, as it is an engine out job to remove the balance shaft. This is a worst case scenario though, and depending on the problem, you might get away with only doing some of the elements. The half job is to just do the chain and tensioner, which fixes the issue for a while (and may be all you want to pay for) but does not resolve the underlying issue.

Rather than try to buy it all online and leave bits out, save yourself the stress and give us a call (09 2636354) or email me at (parts3@4mercs.co.nz) and we’ll put together a quote for you, and put you in touch with a good specialist workshop. 

Here are the schematics for the parts in question, the chain and all 4 rails and the tensioner (100) in the first picture. The cam adjusters in the second.











And here's the culprit...

The old style countershaft gear with worn teeth vs the upgraded part (from one I pulled off the shelf) - note the more pronounced teeth...


M273 Idler Gear/Timing Issues 

On the E550 with the M273 engine, the idler gear is the root cause, which can lead to the same chain of events as above, but is not as common. In this case, the idler gear is able to be replaced without taking the engine out, so often you just need the idler gear, chain, rails, tensioners and maybe cam adjuster plates. The new plates have higher tolerances, so will allow some movement before the timing is thrown out. There is a serial number cutoff for this too: 2739..30 088611, so after this engine number, you’re all good! 

Just like the M272, first picture is a worn, old style idler gear next to a new, upgraded, off the shelf gear. 


Intake Manifold & Actuator Lever: Plastic or Alloy 

As if the M272 and M273 weren't plagued with enough problems, in comes the manifold. Basically, the flaps that actuate the variable length manifold get clogged with oil and carbon that comes out of the PCV system, making the flaps have to work harder and harder…until the plastic linkage (which get brittle from exposure to heat cycles) on the swirl flap actuators break.









We carry either replacement plastic kits to fix this, or some stronger aftermarket metal linkages with the arms. If that's all the problem is...then problem solved! However, often this just covers the symptoms of the wider problem, which is the manifold being clogged beyond all reason, like the traffic at the Auckland border will be this Christmas. This can lead to flaps completely failing and  pieces of these flaps finding their way into the combustion chamber. Not ideal! We sell new aftermarket manifolds, which are significantly cheaper than genuine ones. 


M272 Thermostat / M273 Thermostat

Both are more or less the same and fail because of age, use and getting filled up with crap - the reason most good things start failing. This generally starts around 100,000kms but there's no rule of thumb. They should be considered a service item  - we sell these all the time. If the car overheats, doesn't get to temperature or has coolant leaks could be a sign yours is ready to go. 



Control Arm Bushes & Ball Joints

Control Arm Bushes & Ball Joints are very common items we sell for W211s. As with anything rubber (on your vehicle), they fail at the worst times! The bushes are pressed pretty firmly into the control arm (Circled in green on the diagram below), so a lot of mechanics just replace the whole arm. However, it is possible to just replace the bush (red circle). We also sell a lot of the ball joints, which go between the control arm and hub (blue circle). If you call up asking for a ball joint you’ll likely be asked, “is the ball joint facing up or down?” so we can figure out which one you’re after - facing down is the strut rod (140) and they only come as part of the whole arm, facing up goes into the lower control arm and they are available separately (20). 


In conclusion...

Of course, there are other things that can go wrong, as with any car model, but this just covers a few of the more common ones! Don’t let this list scare you away from W211s, they are awesome cars! These are just what we tend to get asked for most commonly, and doesn't mean every car will fail in the ways stated above.

If buying a 2006 - 2008 model, insist on seeing the service history before purchasing - the issues mentioned may have already been fixed, especially if the car has relatively high Ks. You could try to find one without airmatic too, some do but most of them tend not to - you'll be able to tell if it has this button or not...

If this still scares you, get a 2009 modelm which are largely free of all the above issues. How could you resist this beauty?



Keeping your R129 fine

Here at Startech we have a special relationship with R129s. We even have a room dubbed the 129 Room where we keep all the second hand parts we have for them, having wrecked too many poor specimens over the years to count… 


We even own this specimen that managed to survive being wrecked (till now at least, when customers ask for parts that we don’t have in stock, none of our cars are safe…)


Here is a list of some of the most common, or noteworthy parts we sell for 129s and the reasons why you might need them.        

Distributor Caps and Rotors

The ol' damp distributor cap is a familiar situation to be in for all pre 1995 500SL owners. This is probably one of the most common parts we sell for R129s. The most common sign of an issue is that the car is running rough, misfiring or won't even start after having been run for a while.

The problem is that condensation builds up when the car goes from being cold to running hot, and sits on the connection points between rotor and cap. As the rotor spins, the film of condensation stops electrical connections, causing uneven ignition.

It is worth checking the rotor cover too. As they degrade, they let in more moisture.

You don’t have to, but you may as well replace rotors at the same time as caps. If you have a 500sl you need two caps and two rotors!


Cam Oilers - Plastic or Metal


There are 16 of these in total in the SL500's. Pre 1992 all of the oilers were metal, but they were switched to plastic, a sign of Mercedes engine parts to come... 

The trouble is the plastic ones get brittle due to exposure to the regular heat cycles and break. The most common sign this has happened is a ticking noise from the engine, because the lifters are not getting enough oil.  

You can replace just the broken ones, but the rest are soon to follow. You could replace plastic with plastic, which is cheaper, but they will eventually break again. For peace of mind you can swap to metal ones and never have to worry about it again!

We try to carry a whole set in stock in case somebody wants to do a complete swap, but they can be slippery things to get hold of!


Fuel Injectors


If your SL is running rough on startup, for around 10 - 15 seconds, and then seemingly coming right, it could be the injectors. Worn injectors tend to drip fuel rather than spray, so the mixture runs rich. Once they’ve ‘come right’ after 15 seconds or so it might seem like the issue has gone away, but later on you’ll probably notice you’re spending more on fuel (not because of a new ‘levy’, or whatever else they choose to call it so it isn’t technically a ‘tax’.) 


Bonnet Insulator


These naturally wear over time, because with exposure to heat the foam degrades. This might make the bonnet too hot to sit on to pose for photos, what a shame...classic car enthusiasts just love when people sit on cars for photos!


Indicator Lamps - Amber, Clear, Amber/Clear


Indicator lamps for R129s come in 3 different variants, amber, clear or amber & clear. It’s up to you what you put on as they’re all compatible. It just depends which look you’re going for: the stock classic look or the more modern look. Don’t ever let your wife tell you you don’t accessorize!


Power Steering Pump Filter


M119 engines in 500SLs have a filter in the power steering pump. It’s a part we should sell more of but don’t because people forget, or don’t know, they’re there. They should be replaced with the gasket as well!


Hydraulic Roof Cylinders


I saved the best for last! - The main cause of failure is the seals inside the cylinders degrade with age and exposure to the hydraulic oil. This makes them leak oil, so they cannot not create enough pressure for the operation it is responsible for. They also dribble in your face as you cruise down those country roads in motoring ecstasy, ruining your immersion.  

While it can be enough to play whack a mole with each cylinder that fails, it is worth doing them all at once, that way it is done and out of the way.     

At Startech we can do either rebuilt individual cylinders or a full rebuilt cylinder set on exchange. Basically we sell you a replacement set and once your Mercedes specialist repairier has finhished the job (and it is a job) you send back your old ones on exchange, just to make sure these valuable little units don't disappear out of our circulation. 

We also sell the oil in 1 litre bottles. If hidden power steering filters weren't enough for you, the tank is inside and underneath the spare wheel!

These are just a few of the most common parts to consider that we sell for R129s. We of course stock all wearable parts for them too: brakes, filters, bushes. Anything you need just give us a call at 0800423697, or send me an email at parts3@4mercs.co.nz