Mercedes-Benz C-Class (W202: 1993-2001)

Corrosion (water-based paint)

In my opinion, rust is by far the number one problem with this car and other Mercedes-Benz vehicles produced between 1993 and 2004. In 1993, Mercedes-Benz implemented a more environmentally friendly, water-based paint.

Unfortunately, the new paint offered less protection from rust. With no galvanizing process, and coupled with steel that wasn’t very corrosion resistant, the W202 C-Class can corrode pretty much everywhere. When buying a Mercedes-Benz from that era, inspecting it for rust should be one of your top priorities.

Mercedes-Benz eventually started galvanizing their cars but it wasn’t until around 2004. The production of the W202 C-Class stopped in 2001.

Here’s why good corrosion protection is important:

Spring perch failure

The spring perch failures are directly related to poor corrosion protection on these cars. The front suspension spring perches are welded to the inner wing. This area, being so close to the wheels, gets splashed with water (and salt in winter). The weld is coated at the factory to provide some protection, but over time moisture penetrates the coating and starts corroding the metal.

Corrosion in that area may eventually lead to one of the spring perches breaking off. If it happens, the suspension collapses and the tyre suddenly has the option to meet with the fender. As you can imagine, this can be dangerous if it happens at the wrong time. You may never see this problem in dry climates with salt-free roads, but otherwise, this is something to consider.

I believe it’s more common to see failed spring perches in the Mercedes-Benz W210 E-Class, probably because of the higher weight, but both models have equally bad corrosion protection, in my opinion.

If you are planning to buy the W202 C-Class, and you live in a wet or cold climate, I recommend getting the spring perches checked and even reinforced after your purchase. You won’t be able to check them before buying the car as you would need to peel off the coating to see the welds. Even then, it’s not obvious if the welds are still good.

Replacement spring perches are available and can be riveted/welded back to the car if the original ones fail.

Biodegradable wiring harness

In the early-nineties, Mercedes-Benz decided to use a biodegradable wiring harness in their vehicles. Unfortunately, it turned out that the biodegradable wiring insulation made from soybeans degrades far too quickly.

It becomes brittle and falls apart over time. The wires become exposed, short-circuit and cause the electrical systems to malfunction. The cracking insulation also makes the wires susceptible to corrosion.

It’s the heat of the engine that accelerates the process of degradation. Therefore, the cables close to the engine are ones mostly affected.

The wiring harness problem affects Mercedes-Benz cars from 1992 until 1996. Both petrol and diesel-powered W202 cars are affected too.

The components that could potentially malfunction because of a damaged wiring harness are fuel injection, starter, alternator, throttle actuator and the ECU. A faulty wiring harness can disable the car, and it is a potential fire risk.

The typical symptoms of a failing harness are electrical errors, problems with starting the engine, poor running and rough idle.

Before buying a 1993-1996 Mercedes-Benz W202, check if the harness has already been replaced. Otherwise, you will have to replace it yourself.

The wiring harness is complex, and that makes it expensive if you buy a new one from the dealership. However, you may be able to find used ones in good condition on eBay. Just make sure that you get one with the updated insulation that doesn’t disintegrate when you touch it.

M104 & M111 engines – head gasket failure

In my opinion, the head gasket is the weak point of these engines. Considering head gasket replacement is inevitable at some point, often around 150k miles.

Before the gasket fails completely, these engines often develop an external oil leak from the head gasket at the back of the engine. Make sure to inspect that area when buying one of these cars.

Once the head gasket fails and is replaced, the new one should be good for another 100k – 150k miles. This issue mainly affects the inline-6 engines, like the M104, because of their long cylinder heads. However, the 4-cylinder M111 engines are also affected, but to a smaller degree.

M111 – “Kompressor” lifespan

These engines are fitted with superchargers. The superchargers are reliable but have a finite lifespan. I estimate that they will need to be rebuilt after around 150k miles.

The engine and other components under the bonnet will last a lot longer, so it’s very likely that the car will need to have the supercharger rebuilt or replaced at some point during its lifetime.

OM604 engine – diesel distributor pump

While the 5-cylinder OM605 and 6-cylinder OM606 diesel engines, in traditional Mercedes-Benz fashion at the time, were equipped with a very reliable Bosch inline injection pump, the OM604 uses an electronically controlled, rotary injection pump made by Lucas.

In my opinion, this rotary pump is less desirable because of its seals that become brittle and may develop leaks. In my view, the OM604 is the weakest engine out of all indirect injection diesel units available in the W202.

“Black Death” (affects CDI engines)

The first two generations of CDI diesel engines may develop leaks from the fuel injector seals (copper washers). When a leak occurs, the gases and the diesel fuel from the combustion chamber can escape and cover the area around the leaking injector with burnt, hard, tar-like substance.

“Black death” is a dramatic name for something relatively inexpensive to fix, provided that you catch it early. Any leaks should be visible once the plastic engine cover is removed. 

If there was a leak, you will see a black mess on top of the engine. You may also smell diesel fuel inside the car when the engine is running. If the leak is large enough, the engine may sound like a steam locomotive due to gases escaping from the combustion chamber.

If left untreated, it can become very expensive to fix – injectors seized in the cylinder head, damaged injectors seats and massive carbon build-up to clean.

Summary of problems & additional information

• Except for the rust, which can be a serious problem, the W202 is pretty reliable. Just like the older Mercedes-Benz cars, it is well engineered and relatively easy to work on.

• Unless you can find a rust free example, I would stay away from this model though. If you do decide to buy it, be prepared to spend some time and money on dealing with the rust in the long run. That is if you live in a wet or cold climate. If you live in a place like Spain, buying a W202 is not a bad idea at all.

• Before buying a Mercedes-Benz W202 from 1993-1996, check if the biodegradable wiring harness has already been replaced. Replacing some wires may sound like a trivial job, but a new wiring harness isn’t cheap.

• The V6 M112 and V8 M113 engines – Mercedes-Benz got both of them right. They are closely related to each other and both are reliable.

• Watch out for potential head gasket problems in the M104 and M111 engines.

• The OM611 CDI diesel engine in the W202 was part of the first generation of Mercedes-Benz Common Rail engines. Read this article about modern diesel engines, which might help you decide if a common rail diesel engine, like the CDI, is the right choice for you.

• The OM604 diesel engine has a distributor pump, which is less robust than the inline injection pumps used in other Mercedes-Benz engines. The seals in the OM604 injection pump may develop leaks.

• All W202 engines are fitted with timing chains, which normally don’t have a specified replacement interval. The timing chains in the W202 are generally reliable, but they will not last forever. Click here to learn more about timing chains and belts.

Petrol engines – specs & performance figures

Diesel engines – specs & performance figures

Petrol engines – technical details

Diesel engines – technical details