Mercedes C class W204

The Mercedes W204 is considered the harbinger of a new era in the brand's history. But what is the case with reliability? Let's get into the details.

The platform in the basis of C-class of this generation is quite classical, with basic rear drive and longitudinal arrangement of a power unit. There are three bodies to choose from - sedan W204, station wagon S204 and coupe C204.

The range of motors is very wide, from inline fours 1.6 to V8 6.2. Transmissions are mainly hydromechanical 7-speed 722.6 and 9-speed 722.9, but you can also find cars with a manual. 

Suspensions in comparison with the predecessor W203 have been reduced: in front instead of "noble" double wishbone design - McPherson, but in the rear there is a multilink suspension on five arms classic for Mercedes-Benz design.

Exterior panels

The body of the model is mostly steel. Only the hood and front fenders are made of aluminum. Everything else is made of galvanized rolled steel with a relatively good quality of paintwork. Former owners of cars of this brand will say "is it quality" and they will be right: by the standards of 90th the paint layer is impermissibly thin, but for the end of 00th and in comparison with some Toyota Camry XV50 W204 is painted perfectly. Especially if the color is metallic, not basic white. 

The paint is elastic, does not peel instantly from sandblasting, chips are usually small, under the handles the paintwork is scratched minimally and does not peel on the edges of the elements. Many potentially problematic areas are carefully covered with plastic. 

Rare copies have additional acti-corrosive treatment, though on 100-thousandth TO it is supposed to inspect the body and its processing if necessary. The problem is that not many cars remain in dealer service to this mileage.

What to look for on cars when inspecting them? Chips are likely to be on the windshield frame, at the upper glass molding, on the edge of the plastic sill cover in its rear. 

The lower door seams, rear body arches and the joints of the rear fenders with the bumpers have quite possibly already started to rust. Corrosion can also be found under the corners of the taillights on sedans and under the plastic trunk liner, in the corners of the doors near the mirrors, under their window moldings and on the rails on station wagons.

If you have an endoscope, it is worth checking the seams of the overmotor niche - if the drains are clogged, not only it suffers, but also the SAM unit, which will be discussed in more detail in the "Electrics" section. It also makes sense to run a camera in the side recesses of the trunk and the inside of the rear arches. 

Damage to the underbody is usually concentrated in the rear. Even in almost perfect specimens you can find corrosion of the rear subframe, rear suspension shock absorber supports, body seams in the recess around the gas tank, tank mounting straps, jack stands, lower edges of external body elements and brackets on the underbody. In neglected cases, you can also find layered body corrosion and even broken off rear subframe ears. 

In the case of V6 and V8 engines, you can also find such problems as damage to the paintwork at the bottom of the engine compartment due to oiling. Of course, this is only in the case of "dead" motors that pour oil from every crevice, but among powerful models there are surprisingly many of them. 

Body equipment

Low front bumper on cars with AMG-package (which could be ordered even with "vegetable" versions of C180) not only breaks along the skirt, but also serves as a reason of "spreading" of front wings: their geometry is broken and front fastening lugs are damaged.

However, even if the fenders were not damaged in the impact, and the bumper is ordinary, you should take into account that it consists of many small and very expensive parts - overlays, fasteners, grilles, etc. It is expensive to change it all together, the original fasteners and holes are broken, so when restoring "for sale" the front part is assembled on "glue, screws and snot".

Modules of daytime running lights in the bumper do not suffer from excessive tightness, gain moisture and burn out, and their surface turns yellow. If DHOs are not used and drive with dipped beam all the time, the lenses burn out in five years and the corrector of their position wears out. The corrector is not changed separately, it is located inside the headlight housing - you have to change the whole part. And for this it is better to address to the masters who have experience of work with W204 - after restyling the fixing bolt of the headlight became hollow, and it is easy to break it with unaccustomedness. Another candidate for breakage is the spare tire mounting bolt.

The turn indicators in the mirrors suffer from sandblasting, the glass gets scratched and turns yellow before your eyes if it is not covered with a film. The mirrors themselves fade (not photochromic film, but usual reflective layer), their heating also fails.

The wiper blades already after five years of operation rust, by the way, the restyling has a different type of wiper mounting, although the blades themselves are compatible. At long downtime corrodes the trapeze bushing, because the steel axle in the bronze bearing and aluminum frame can not help but corrode when exposed to moisture. 

In general, there are enough small and not so small problems. The main risk factors are the northern climate and low qualification of craftsmen. From good news: as the price on the secondary market is kept high enough, it is still cost-effective to maintain and preventively repair W204.

Interior

The most obvious trouble is the quality of materials, especially on cars before restyling. However, the combination seats are bad both "before" and "after" - the fabric on the center insert requires regular cleaning, and the leatherette side bolsters need replacing. The seats were often repaired under warranty, with the passenger seat having a more expensive cushion cover because it is sold with the passenger occupancy sensor.

Rare fabric interiors hold up better, but again, it is better to clean regularly - fabric absorbs dirt. Natural leather interiors are also not bad, except that light-colored variants expectably require frequent maintenance. 

Armrests and center tunnel lining also quickly lose their look, and here the difference between restyling and prerestyling is noticeable. In older W204s, the coating of the center trim quickly fades and scratches, and the armrests squirm.

The steering wheel coating is not bad - even in the prerestyles. With mileage up to 200 thousand and little or no care the steering wheel keeps its appearance: it loses leather texture little by little, but it does not fade and does not crack. Only rubbing buttons spoil the look. 

The material of the front panel in the prerestyling is obviously unsuccessfully chosen - it is very cheap and "plastic", both to look and to touch. Silver inserts quickly fade, "royal lacquer" is covered with ugly scratches - 10-year-old C-class can look very sad. In 2011 with restyling the quality of materials was improved, but glove box lighting still often does not work because of broken wires, and the axle of the multimedia system control joystick easily breaks from careless impact.

The door seals also quickly fall into disrepair, and the barchotka - the lower gland of the glass - wears out and collects debris after several years of operation. 

All this, of course, "does not affect the speed", although one could expect better durability from Mercedes by habit. But there is something more serious than scratched plastic and shabby leatherette.

Electrics

The steering column lock has drunk a lot of blood. Usually a kopeck motor breaks in it, as in children's toys, but the car gets up intentionally. With a locked steering wheel you can't go far, and often you can't even start - even a tow truck is not always possible. Fortunately, the system starts to malfunction periodically before it fails completely. 

If this happens, it is better to immediately remove the blocker, change the motor, microswitches and gears, and at the same time remove the slaughter on the working surfaces and lubricate everything. At the same time, you can grind off the locking shaft projection, it will reduce the load on the lock and reduce the probability of breakage. There is an alternative option - just throw out the blocker and put an emulator from China, but it will have to be prescribed in the "brains".

It is much worse if the steering shaft is locked irrevocably, and attempts to turn on/off the ignition and warming up the cabin do not help. In this case, you will not be able to remove the blocker in 15 minutes, you will have to remove the column, drill the body of the blocker and crank the gear by hand, and the total price of repair will exceed 200 dollars, not counting the tow truck. Separately, the blocker is not sold, only as part of the steering column, which at best costs from 1000 dollars. 

It is also possible to note rare breakdowns of climate control shutters and limited resource of air conditioner compressor with about 200 thousand kilometers of mileage. It is here of variable volumetric capacity, without a clutch, and the minimum working stroke is kept even in the switched off condition in winter, that kills it especially quickly. Check the work of taillights - on the cars before restyling the wires are burned off at the boards.

In general, W204 has a lot of electrical equipment, and it is complicated. Even the simplest systems are controlled by own controllers. Hub system with front and rear SAM current-distributing blocks is quite debugged, but it is afraid of water in the front block (I spoke about this risk in the section about the body), overloads, power surges and bad electricians. It also happens that the units suffer from corrosion and broken firmware, and the rear unit has a resistor fall off. New SAM blocks cost, of course, prohibitive money, but there are serviceable second-hand for 150 dollars.

To reduce the risk of block failure, try to do without boosters and light as little as possible. Do not charge batteries without disconnecting them from the mains, and remember to disconnect the backup battery in the trunk on post-restyling cars when idling together with the main battery. Keep an eye on the serviceability of radiator fans and the condition of the engine compartment power distributor, and in case of corrosion of the distributor, connectors or difficult start of the fan immediately contact the service. If you follow these simple rules, the probability of expensive breakdowns will be reduced to insensible.

But the owners, of course, more often behave irresponsibly: they take the car for service to illiterate electricians, persistently try to open frozen windows, for the sake of beauty every six months fill the under-hood compartment with water. In theory W204 allows to put dashboards and multimedia systems and trunk lid drive from W212, seats - from coupe C207, and also to change headlights, cruise systems and similar elements for more desirable ones. At the service of "kolkhozniki" is a set of software Vediano, which can be used to re-flash the blocks and correctly prescribe all the changes. Unless, of course, the one who does it, did not just google "put the dashboard from W212 on W204" and try to do something according to the instructions from the forum.

Running gear

Braking system

Brakes of W204 are made qualitatively, but are very loaded - even weak C200 has very good dynamics. At the same time, cars with age under 10 years can have perfectly working brakes. Resource of original disks and pads is typical, on cars with automatic transmission disks serve from 50 to 100 thousand (depending on driving style), pads are about two times less. There is only one weak point: the rear ABS setting rings rot. Fortunately, they are changed separately from the hub. 

Suspension 

The transition to MacPherson in front affected the resource not in the best way: shock absorbers can start to leak after 60 thousand kilometers, springs break. Support bearings do not like operation in mud, they can be happy with crunching after several hours of driving on a dirt road. Levers are more reliable, with relatively careful handling often live up to a hundred thousand. The front longitudinal does not like holes and bumps, the rear transverse - lateral overloads and thin rubber. 

Of the elements replaceable separately - hydrofilled ball bearing of the longitudinal arm. All others should be replaced as a complete assembly, but economists manage to re-press the silent blocks with predictably lower than the original resource.

Rear suspension of traditional Mercedes design with 5 levers per side, but for W204 and 212 it was a little easier, and as a result the resource of the main "links" decreased to 100-150 thousand mileage. 

Steering control 

It differs constructively from modification to modification. The main mass of W204 (all cars before restyling and versions with V6 after restyling) are equipped with usual GUR. The original Bosch pump is expensive, serves up to 150-200 thousand mileage - the filter of unsuccessful design fails. If you change it to a similar one from Chevrolet Niva, you can even be comforted by the fact that it is not quite a "kolkhoz", because Bosch also supplies the part to Niva.

The racks themselves are not a sample of reliability, especially often they flow on cars of the first releases: as a rule, it is a consequence of long exploitation with a dying pump, which supplies oil with chips. If there are no leaks, but there are knocks, then usually the reason is in worn side bushings - the issue is solved by replacement with fluoroplastic parts. 

The design with EPS, which appeared on cars after restyling, is similar to Volkswagen's. There is the same double rack with a power part on the opposite end from a steering column. The system is well tuned, though surprisingly steering rods are stronger than the rack itself - more or less strong side impact leaves the rods without damage, but the rack is knocked out, damaging the steering shaft.

Transmissions 

General problems

The mechanical part of the transmission is quite strong - only the intermediate support of the rear PTO shaft requires regular control, and on all-wheel drive versions also bearings of the shaft passing through the engine crankcase. The resource of front ball joints is less than that of rear ones, but in general you can not worry about them.

Manual transmissions

Rarely occurring manual gearboxes of 711.6 and 716.6 series have nothing to scold for - only the gear selection mechanism wears out up to 300 thousand, and then there are chances of bearing wear. 

Also on W204 there is such option as Sequentronic - it is a robotized transmission on the basis of 716th box, but it is rare. There is only one clutch, and the algorithms of work are corresponding.

Automatic transmissions

Hydromechanical automatic transmissions are represented by three series. The majority of cars before restyling are equipped with the old five-speed automatic transmission 5G-Tronic series 722.6, mainly 722.640 W5A580, a rather strong version of this transmission. The weakest versions had the lightweight 722.618 W5A330.  

Cars with V6 engines before restyling are equipped with 7G-Tronic - 7-speed automatic transmission of 722.9 series, more precisely 722.903/722.902 W7C700, and the bulk of cars produced since 2011 - its modernized version 722.9Plus, it is also 722.997 W7C700 with a new mechatronic board and improvements on the mechanical part.

5G-Tronic

The old five-speed gearbox is the most well-established design by the end of the release. Reliability at oil change at least once in 60 thousand is very high, its 200-250 thousand at least before the appearance of problems with the torque converter lockup pads and lockup solenoid it passes for sure. And if you do not race, repair the torque converter in time and change oil more often, it can go more than 500 thousand without repairs. 

Breakdowns of 722.6 are usually related to shocks due to a worn out and working with shocks on cold GDT lockup, or accidental - for example, due to a clogged filter or overload. Small troubles like leaky wiring gland or selector problems are also possible, but they occur at high mileage and are treated inexpensively.

Despite the presence of only five stages and a rather old design, the dynamics and fuel consumption of cars with in-line "four" and this automatic transmission is slightly worse than with a seven-speed. Certainly, it is difficult to reach indicators of less than 5 liters per hundred on the highway with a gasoline engine, but it will not cost extra money for repair, and b/a boxes are very inexpensive and are found in abundance.

7G-tronic

The first version of 722.9 is an extremely progressive design. In the mechanical part it is still felt that it is created on the basis of the old box, there are even matching parts. But the kinematic scheme is completely new, with one rigid locking, compact and with a large dynamic range.

The most obvious change is that the control unit has been moved inside the automatic transmission, resulting in a mechatronic. It is a pity that the Siemens board is not designed for the temperature mode over 130 degrees, which is typical for this automatic transmission due to problems with the design of the cooling system. The heat exchanger used turned out to be inefficient due to miscalculation of the cooling system circuit capacity, and the target temperature was chosen unsuccessfully - it was the first MB experience of increasing the operating temperature of the ACP up to 115-120 degrees. 

Mechatronic electronics board is one-piece, and first of all the speed sensors on it fail. Now they have learned to solder them, and repair and re-bind the boards, and even 5 years ago it was a big problem. 

The wiring harness of the automatic transmission has also become cheaper and over time has become heat-resistant, as well as the box oil seals. High temperature also contributes to wear of linings of the mechanism of locking of GDT that leads to necessity of its repair at mileage up to 200 thousand. 

At the same time, the mechanical part is strong enough, with a good reserve - it is possible to ruin the oil pump or bushings only at long operation on dirty oil. Leaks of the oil pan are related to its unsuccessful design, but there are no special problems with it at regular oil change and observance of the temperature regime.

It is difficult to keep an eye on the oil level as there is no oil dipstick, although it can be ordered and supplied separately. Because of the very high temperature, the box requires the use of oils with a new tolerance and does not treat universal oils well. 

Even early editions of the box have a problem with a cracking ACP bellhousing, a purely mechanical trouble due to a strength miscalculation.  

The whole set of problems provided the box with a bad reputation - on the first W204 at mileage of 60-90 thousand the automatic transmission was often sent for repair. Dealers changed mechatronics and rebuilt the automatic transmission several times. The main points have been eliminated by 2010, and a little later a new version, 7G-Tronic Plus, with a new electronic board, and at the same time and improved cooling system was released. 

The good news when buying cars with 722.9 is that this unit is almost perfectly diagnosed by the scanner, because the electronics constantly monitors the optimum shift pressure in each of the packages and the base pressure in the box. According to the data on adaptations, you can judge the condition of a particular instance, at the same time it is worth looking at the software version - it has been significantly updated, improving the algorithms of work.

7G-Tronic Plus

The new version of the 722.9 gearbox served well until the appearance of the 9-speed 725 series automatic transmission, because the main problems of the design were solved. The operating temperature was reduced, which improved the working conditions of electronics, wiring, GDT, friction and oil pump. Finally, the service regulations have been corrected - now the box officially requires regular oil change once in 60 thousand. 

The oil itself has been changed to even more heat-resistant, initially it was with the tolerance 236.14, and after with the tolerance 236.15, they even differ in color, the new oil is dark blue instead of pinkish-yellow. The assumption is that you can't mix them, and the new hydros don't allow the old oils to be used. 

This opinion is widely supported by oil professionals, but in practice it's not so terrible, it's just that adaptations on the wrong oil won't be perfect. Moreover, on ordinary mineral oil of Dexron III standard the box also works, though not for a long time. Mineral oil loses its lubricating properties in ten-twenty thousand mileage, contaminating the box. And synthetics is selectively aggressive to a number of materials 722.9, and there is always a chance to pour something unsuitable. In short, you really should use original oil, but if you put "old" oil into the 722.9 Plus instead of "new" oil, no one will die.

The reliability of this design is slightly inferior to 5G-Tronic (722.6), but it is still much more expensive to repair. In case of careful operation, GDT linings serve more than 200 thousand, and the mechanical part of the unit can pass 500 on condition of intermediate repair at mileage of about 250-300 thousand. 

Four-wheel drive

Almost all all-wheel drive W204s are with V6 engines. In the 4Matic version the drive is constant full, in the transfer case here is a full differential. The transfer case itself is very reliable: large gears and reliable case, large roller tapered bearings allow it to pass even with powerful motors far beyond 200 thousand without problems. Rare problems are connected with bearing cages failures, even less often the differential is damaged, which is made here according to the scheme of planetary gear-divider.

Engines

Engine range of W204 is unusually wide - only in-line "fours" can be conditionally divided into three generations. The main engine of the cars before restyling is M271 in the version with distributed injection and compressor. Since 2009, the transition to the M271 Evo version with direct injection and turbocharging began. And in 2012, a new motor of the M274 range was introduced, in turbocharged and direct injection version, with completely new timing and sprayed iron coating of cylinder liners, instead of cast iron liners. V6s come in two generations - the older M272 and the radically different M276.

The range is not exhausted here - there were also powerful 8-cylinder versions and rarely seen in our country diesel.

In-line engines of the first generation

The basic variant is a motor with a volume of 1.8 liters, M271KE18ML with an output of 156 and 184 hp for versions C180 and C200, but since the summer of 2008, the junior variant of 1.8 replaced the engine with a volume of 1.6 liters, M271KE16ML, with the same 156 hp.

M271 motors are quite strong, but, unfortunately, they have a serious miscalculation with the design of stars of phase adjusters, which greatly reduces the life of the timing chain and can cause even its flight from the stars, as well as wear of the stars themselves. In the phase adjuster, the unsuccessful design of the cocking spring and alignment mechanism over time leads to oil pressure leaks, vibrations and misalignment of the outer sprocket and camshaft. 

All would be well if these parts were inexpensive, but a set of stars costs at least $800, now there are non-original and remanufactured parts, but their quality floats, and the design of almost all copied from the failed original. As a result - more than five variants of phase controllers from the manufacturer for ten years of motor production and numerous dissatisfied owners.

The compressor and distributed injection versions of the motor were well established by 2008 and are otherwise very reliable. The compressor quietly serves up to 200 thousand, the wear of bearings at basic boost pressure is unlikely, the wear of the drive belt and rollers is increased, but these are inexpensive parts.  

From serious disadvantages of M271 it is possible to note unsuccessful system of KVKG, ventilation of crankcase gases, decrease of efficiency of which work is aukacaet by liquefaction of oil by gasoline and the reduced resource of oil, besides in winter it is inclined to freezing. Every four or five years it is better to change the ventilation pipes, they are heavily clogged from the inside, the capacity of the system is reduced, check valves are often wedged. The main sign of problems - oily throttle valve It is also necessary to watch for oil leaks through the gaskets of the heat exchanger in the oil tank, they ooze over time. 

Second generation inline engines

The M271 Evo engines, which appeared in 2009 on the C180, C200 and C250 versions, although they have the same index, but are very different from their predecessors. Supercharging is realized by a turbocharger, and injection is direct, besides, the engine management system is completely different. As a result - a new round of troubles.

The volume of gasoline getting into the oil has become larger, and as a consequence, the importance of proper operation of the crankcase ventilation system has increased. And the problem remains: the tubes still require regular replacement, or you need to use very high quality oils.  

The power system is quite reliable, because Mercedes has already had an unsuccessful experience of introducing direct injection on the 271st series of engines on W203, and as a result the work on mistakes has been done. There are no problems with EGR, fuel pump and injectors, everything is well diagnosed and works without surprises.

Improved power performance of the motors, increased range of control of the phase adjusters, increased load at low engine speeds due to the new transmission caused a new round of problems with the timing. In M271 Evo the guaranteed life of chains fell from 80-100 to 60 thousand kilometers.

The turbine caused problems when oil pressure dropped and the mileage exceeded 100 thousand, but the manufacturer solved this problem by putting a restrictor in the banjo-bolt of the turbine drain line. The part is pennies, about 10 dollars, and it is worth to change it.  

The attempt to increase the operating temperature of the engines led to a decrease in the life of all rubber parts, and in particular - the gaskets of the oil tank and thermostat gasket, which were not exemplary before. As a result, the motors often do not warm up, and the fuel in the oil becomes even more. 

Third-generation inline engines

Motors of the M274 family on the W204 are represented by a single variant M274DE16AL with a displacement of 1.6 liters and an output of 156 hp for the C180. The main difference between the M274 series and its predecessors is the use of a thin-walled liner made of sprayed iron composite rather than a cast iron liner and a completely new timing mechanism.  

The first solution definitely increases the "disposability" of the motors, but it is quite reliable in operation, it is not Alusil. The coating can even be honed again, and its wear resistance is higher than that of a cast iron liner. But only in case of problems with rings or abrasive penetration into the intake it breaks through or scratches to a depth that does not allow restoration.

The piston group obviously lasts longer than on the 271 Evo, where significant wear of the liner in the TMT area was observed after 250 thousand. The timing resource has also grown considerably, though, it is far away from the problem-free M111 family with their "eternal" chain, but 150-200 thousand chains can pass. 

But here is a surprise - the forgotten problems with the clutch of the phasoregulator appeared again.  The clutch with the code A 270 050 08 47 at first slightly knocks, and then it suddenly turns - and at once with damage to the cylinder head, valves and even pistons, they are not designed for blows. This clutch was put in until spring 2014, so almost all W204s with M274 are at risk. You have to put a new clutch number A 270 050 11 47, it is stronger. It can also turn, but such cases are extremely rare and occur only with frankly negligent attitude to the knocking motor. The clutch was replaced under the recall campaign, so it is not a fact that you will have to replace it personally.

One more specific trouble of M274 concerns the adjustable pump - it breaks the lever of adjustment drive. There was a recall campaign on the pump too, and this part was probably replaced, but it's worth double-checking. Pulse disks on M274, on which camshaft position sensors are located, still rotate the same way, you have to monitor their position, and if they are displaced, they need to be welded to the shafts. 

First generation V-engines

It is possible to write more than one page about motors of M272 series, which in variants M272KE25, M272KE30, M272KE35 with displacement of 2.5, 3.0 and 3.5 liters were put on C230, C280-C300 and C350 models until 2009-2011. Those who wish to get acquainted can recommend reviews of Mercedes W211 and W221, as well as the material devoted to comparison of M272 with the previous 6-cylinder family M112.

If to summarize briefly, the combination of tender alusil block, high operating temperature, leaky intake manifold, spitting remnants of plastic flaps into cylinders, unsuccessful timing and aggressive adjustment of control system, allowing easy detonation, leads to scuffing and oil build-up in these motors already at mileage of 150-200 thousand. 

In theory alusil allows to create almost eternal motor with resource of piston group more than 500 thousand, in fact at such runs they can have no wear of cylinders and rings, but in practice scoring threatens at any mistake, and repair is carried out either by replacement of short-block, or gilzovka, that in case with the motor 3,5 is rather difficult and expensive event.  

Also the motor has expensive phasoregulators, 400-500 dollars each (and there are 4 of them), a current oil filter cup and a bunch of smaller problems. It's possible to do an overhaul with replacement of everything on M272, but even at relatively high cost of W204 on the secondary market it will be hardly financially justified.

V-twin engines of the second generation

The M276 engines on this generation of Cesca come in just one variant, the 3.5-liter, 306-horsepower M276DE35 on the C350 version from 2011. The M276 engine lineup is very different from the M272, they even have a 60-degree block camber angle to avoid the use of a balancer shaft. Here, as well as on the M274, is used sprayed coating of the liner of iron composition, very strong and wear-resistant. 

The timing mechanism has become much more reliable - there are separate chains for each cylinder head and one short chain for the intermediate shaft, a simple design of tensioners and a stronger design of phase adjusters. The first two years of production the chains were white in color, they are prone to pulling out and should be replaced - this can be done under the extended warranty.

Finally there was a normal intake manifold, without broken flaps and suction, and after 2014 the engine was lowered to 92 degrees. Since the 105-degree thermostat on earlier cars creates a lot of problems with excessive crankcase ventilation system zakoksovka and wear of rubber and plastic components of the engine, it is recommended to replace it with a late 92-degree, and the control unit to flash for early inclusion of fans.  

But you'd be wrong if you thought it was a trouble-free motor. Chain knocks on motors with engine numbers up to 1579 XX 60 022333, 2768 XX 30 001280, 2769 XX 30 406602, and 2789 XX 30 103674 are caused by the hydraulic tensioners and phase adjusters taking a long time to fill with oil at startup. A solution in the form of a check valve is being implemented by the recall company. Cold chain knocking requires rework, and if the car is serviced by a dealer, it will be free of charge.

The second serious problem is related to the phase control clutches and control mechanism. The impulse disks still fall off the shafts, and the clutch itself, as on the M274, can twist. Since the motor is not supercharged, the clutch turns much less often, but the essence of the problem is the same. The new version of the clutch A2760503700 is reinforced, and if there are check valves at the chain tensioners and the clutch channel, the knock is still there, then they should be changed. The price of the clutch is currently around $300, but they are usually changed in pairs. All repairs so far are very financially serious due to expensive parts and lack of non-original, so if the car was not serviced at the dealer, it is a good reason to ask for a discount of 200 thousand for minor repairs.  

In general, this line of motors has become much more reliable than M272 - there are no complaints on the piston group and power supply system in case of timely elimination of timing problems. The main thing is not to forget to update the software of the motor, it has been significantly improved, reducing the tendency to detonation even on Ai-95 and even on variants with thermostat at 105 degrees.

Diesel engines

Diesel engines on the C-Class are few, less than 5% of the offer, and they are represented by variants 2.2 liter OM646 Evo, 2.1 liter OM651 and 3.0 liter OM642, well known from the M-Class W164 and W211.

The OM646 on C 200 CDI, C 200 CDI BlueEFFICIENCY and C 220 CDI up to 2009 has problems with intake contamination, fuel equipment flooding, sticking injectors, glow plugs and pressure sensor in the rail. The motor is very reliable, it can go 300, 400, and more thousand kilometers before overhaul.

Its successor OM651, which replaced the honored motor in 2009, is prone to oil pressure sagging due to untimely triggering of the solenoid valve of oil injectors and wear of the oil pump, which appears mainly in the case of its use with an automatic transmission. Automatic transmission avoids the motor operation on dangerous modes with high load and low revolutions. 

Large diesel V6 OM642 for versions C300CDI, C320CDI and C350CDI is much more complicated and expensive in service, but it can also be quite recommended to buy. A rather specific list of motor problems can be found in the article about X164.

Conclusion

If you do not suffer from perfectionism, squeaky plastic interior is not annoying, and the budget is limited, you can consider buying a prerestyling with M271 engine and 5-speed gearbox, and even better - find a variant with diesel OM646. Variants with V6 M272 are obviously more risky. After updating the interior became noticeably better, V6 motors became more reliable, but with in-line "four" not everything is so unambiguous - M271 Evo can hardly be recommended to purchase, but M274 - quite. If there are no strong restrictions on money, it is better to consider the latest W204 with dealer service and fulfillment of all routine procedures and warranty repairs.