Mercedes-Benz W124 (1984-1997)

Two used Mercedes-Benz E-Class cars, W124 models, 4-door saloons

 

Reliability & common problems

This section covers the potential reliability issues that you might have with the Mercedes-Benz W124. Click on the buttons below to read more about the typical problems that fall outside the scope of routine maintenance.

Corrosion (water-based paint)

In my opinion, rust is by far the number one problem with Mercedes-Benz vehicles produced between 1993 and 2004. This is because in 1993, Mercedes-Benz implemented a more environmentally friendly, water-based paint. The post-facelift W124, called the E-Class, is affected by this change. Unfortunately, the new paint offered far less protection from rust.

The pre-facelift W124 models had reasonable corrosion resistance, but because of their age, you should still pay a lot of attention to any rust spots and the condition of the floorpan. Corrosion is your number one problem with any older vehicle. Suspension and engine parts can be replaced, but a rusted body can be the death of a car.

Biodegradable wiring harness

In the early-nineties, Mercedes-Benz decided to use biodegradable wiring harnesses 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 W124 cars are affected. For most models, the problem started in 1993, however, it was earlier in the case of the M119 engine. Also, cars with the KE-Jetronic are unaffected.

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 1992-1996 Mercedes-Benz W124, 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.

M102 engine – single-row timing chain

The early M102 engines were originally fitted with single row timing chains, and there have been cases of premature failures.

In my opinion, any M102 engine with a single row timing chain should have the chain and tensioner replaced every 100,000 miles or earlier if the chain becomes noisy. Neglecting to replace these parts can result in serious engine damage (valves hitting the pistons).

Mercedes-Benz updated the M102 engine to receive a double row timing chain in 1988. These chains are a lot tougher, and under normal conditions, should last the “lifetime” of the engine. “Lifetime” can be very roughly defined as 200,000 miles.

M102, M103, M104 and M111 – head gasket failures

The head gasket is a weak point in these engines. Considering head gasket replacement is inevitable at some point, often in the 100k – 150k miles range. 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 miles. This issue mainly affects the 6-cylinder engines because of their long cylinder heads. The 4-cylinder engines are also affected but to a smaller degree.

If you’re curious why the head gaskets fail more often in the inline-6 engines – it’s because of the difference in thermal expansion between the cast iron engine block (11 m/m.K x 10-6) and aluminium alloy cylinder head (22 m/m.K x 10-6).

As you can see, the expansion coefficient is two times higher for aluminium. This means that when the parts get hot, the aluminium cylinder head expands twice as much as the iron block. The longer the engine, the more pronounced this effect is. The head gasket, which sits between the engine block and the cylinder head, has to deal with these expanding parts.

This was a relatively new engineering problem to solve at the time as former Mercedes-Benz engines had cast iron cylinder heads. Aluminium alloy started being commonly used in the 1980s to make lightweight cylinder heads. These days, the engine blocks are also made out of aluminium alloys.

M102 & M103 engines – KE-Jetronic fuel injection

The M103 and later M102 engines were equipped with a mechanical, Continuous Injection System (CIS) called KE-Jetronic, which was designed by Bosch. The system itself is well-engineered and reliable.

The problem is that most repair shops these days are clueless as to how this system works. Unless you can find a specialist or you understand it yourself, trying to get a KE-Jetronic problem solved might not be easy.

If you find a car that runs well, it will most likely keep going as the injection system doesn’t require any special maintenance. If it does break down though, it will be trickier to fix than a more modern electronic fuel injection system.

If you already have a car with KE-Jetronic and you are experiencing problems, often they can be fixed by replacing the vacuum pipes as the system is sensitive to vacuum leaks.

 

Make sure you check the following points before purchasing a car with KE-Jetronic:

  • Idle quality – The idle should be even when cold and warm. The engine should not die or hesitate when coming to a stop (out of gear in a manual transmission car).

  • Power delivery – it should be smooth throughout the rev range. There should be no hesitation when pressing on the accelerator pedal.

  • Cold starts – see how well the car starts when the engine is cold.

  • Hot starts – when warmed up – shut the engine down for 10 minutes and see how well it starts then. This step is important, repeat it twice.

It everything works well, you should be OK.

Engines with KE-Jetronic should not be run on LPG. It is possible to convert it to LPG, using a second generation system, but it is not a good idea. In fact, I recommend that you never buy a car with KE-Jetronic that has ever had an LPG installation fitted for two reasons:

  1. The fuel injection system has a mechanical fuel distributor, which is lubricated by petrol. When you switch to LPG, the distributor will be running dry and start wearing out.

  2. With a simple second generation conversion, there is a risk of gas explosion in the intake manifold, which has a large volume. If this happens, you would be left stranded on the roadside with half the vacuum pipes blown off the engine. Even when you fix the car, it will likely never run the same due to the damage that was done (bent air flow sensor plate, damaged vacuum pipes and likely air leaks).

M119 engine – plastic chain guides & oil tubes

The M119 engines are reliable apart from a couple issues related to the plastic parts inside the engine.

The first problem is that over time, the plastic upper chain guides in these engines may develop cracks and pieces of the guides can break off. If they do, the timing chain loses tension and is at risk of skipping, which makes the camshafts go out of sync. It is rare, but it can cause some serious engine damage if it happens (valves hitting the pistons).

In my opinion, the guides should be replaced as part of preventative maintenance at around 100,000 miles.

Another issue, which could potentially damage the engine if left untreated, is the plastic oil tubes – 16 of them in total. These little pipes become brittle and may crack from the heat of the engine and the exposure to oil. When they break or lose their end caps, the hydraulic lifters do not get enough oil, and the engine develops a ticking sound.

The oil tubes used to be metal, and they were changed to plastic in 1993. The cars with the metal tubes are problem free. Fortunately, replacing the plastic oil tubes is a relatively small job.

OM603 engine – trap oxidizer and cylinder head issues

In 1986 and 1987, the OM603 engines for the US market were fitted with a diesel particulate filter, also called the trap oxidizer. These traps would get very hot and there were cases of trap oxidizers causing issues with the aluminium cylinder heads. There were also occurrences of turbochargers getting damaged by the debris from the trap oxidizers.

This was a big issue for Mercedes-Benz, so a campaign was launched to have these filters removed free of charge. If you are in the US, check if the car you are planning to buy still has the trap oxidizer (unlikely). Trap oxidizers were never installed in European cars.

Additionally, the weakness of the early OM603 engines were the head gaskets and the aluminium alloy cylinder heads. There were cases of cracking cylinder heads and head gasket failures in these long inline-six engines. The engines that were fitted with trap oxidizers were especially vulnerable.

Mercedes-Benz redesigned the casting moulds a couple times to combat this issue. I believe that the trap oxidizers were a big contributor to the problem of cracking cylinder heads because the occurrence of these failures seems to be much higher in the US than in Europe. The length of the straight-6 engine may also be a contributing factor.

The original #14 mould cylinder heads are considered to be the weakest, while the best ones are #18 and #22. You can check the mould number by looking at the cylinder head from the injection pump side. The number should be above the second injector. It will look like this: 603 016 14 01.

Anyway, head gasket failures in European OM603 engines are not as common, in my opinion. If you are planning to buy a car with one of these engines, regardless of where you are, remember to inspect it for any head gasket issues.

Another option is to consider the smaller brothers of the OM603 engine – the 5-cylinder OM602 or the 4-cylinder OM601, both are less likely to develop head gasket problems. The OM601 in the large W124 is painfully slow though.

Summary of problems & additional information

  • Corrosion is your number one problem with any older vehicle, including this Benz. Suspension, interior and engine parts can be replaced, but a rusted body can be the death of a car. The pre-facelift W124 has better corrosion protection than the following generation of Mercedes-Benz cars, which developed a reputation of rusting easily due to the introduction of water-based paint. The W124 models made after the 1993 facelift are more susceptible to corrosion.

  • The W124 chassis shares many parts with the smaller Mercedes-Benz 190 (W201). Both models were designed with longevity in mind. A diesel W124 could potentially be a million-mile car when looked after. Petrol engines are long-lived too.

  • The indirect injection system in the diesel cars is very reliable and relatively insensitive to fuel quality. This is because the inline injection pump is lubricated by engine oil, unlike in modern cars where diesel fuel itself is the lubricant. Many people choose these vehicles for vegetable oil conversions (in countries where it is legal).

  • Apart from the occasional head gasket replacement (petrol engines and potentially the OM603 diesel engine), all engines are reliable. With proper maintenance, they can last a very long time. In case of the V8 M119 engine, also watch out for cracking chain guides and oil tubes.

  • The KE-Jetronic is an interesting piece of engineering and a part of automotive history, but it may be difficult to service. If you plan to use the car as a daily driver, it’s better to look for the M111 or M104 engines with electronic fuel injection, which all car mechanics are familiar with. These engines are also happy to run on LPG if that’s your thing.

  • All W124 engines are fitted with timing chains, which normally don’t have a specified replacement interval. The timing chains in the W124 are generally reliable, except for early M102 engines, but they will not last forever. Click here to learn more about timing chains.

  • Before buying a Mercedes-Benz W124 from 1992-1996, 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. For most models, the problem started in 1993, however, it was earlier in case of the M119 engine.

 

Mercedes-Benz W124 specifications

This section contains Mercedes-Benz W124 specifications. You will also find technical information regarding the engines used in these cars. Press the buttons below to display the specs and engine technical details.

Petrol engines – specs & performance figures

ModelEngineDisplacementPowerTorqueComments
The "E" in petrol models stands for "Einspritzung", which means fuel injection.
200 (KAT)M102 1997 cm³ / 121.9 cu in105 PS / 77 kW170 Nm / 125 lbf⋅ftCarbureted engine, catalytic converter
200M1021997 cm³ / 121.9 cu in109 PS / 80 kW165 Nm / 122 lbf⋅ftCarbureted engine
200 E (KAT)M102 1997 cm³ / 121.9 cu in118 PS / 87 kW172 Nm / 127 lbf⋅ftCatalytic converter
200 EM102 1997 cm³ / 121.9 cu in122 PS / 90 kW178 Nm / 131 lbf⋅ft
230 E (KAT)M1022299 cm³ / 140.3 cu in132 PS / 97 kW198 Nm / 146 lbf⋅ftCatalytic converter
230 EM1022299 cm³ / 140.3 cu in136 PS / 100 kW205 Nm / 151 lbf⋅ft
200 E and E 200M1111998 cm³ /121.9 cu in136 PS / 100 kW190 Nm / 140 lbf⋅ft"E 200" from 1993
220 E and E 220M1112199 cm³ / 134.2 cu in150 PS / 110 kW210 Nm / 155 lbf⋅ft"E 220" from 1993
260 E (KAT)M1032599 cm³ / 158.6 cu in160 PS / 118 kW220 Nm / 162 lbf⋅ftCatalytic converter
260 EM1032599 cm³ / 158.6 cu in166 PS / 122 kW228 Nm / 168 lbf⋅ft
280 E and E 280M1042799 cm³ / 170.8 cu in197 PS / 145 kW270 Nm / 199 lbf⋅ft"E 280" from 1993
300 E (KAT)M1032962 cm³ / 180.8 cu in180 PS / 132 kW255 Nm / 188 lbf⋅ft
300 EM1032962 cm³ / 180.8 cu in188 PS / 138 kW260 Nm / 192 lbf⋅ft
300 E-24M1042962 cm³ / 180.8 cu in220 PS / 162 kW265 Nm / 195 lbf⋅ftKE-Jetronic, 1989-1993
320 EM1043199 cm³ / 195.2 cu in220 PS / 162 kW310 Nm / 229 lbf⋅ft
300 E 3.4 AMGM1043314 cm³ / 202.2 cu in272 PS / 200 kW330 Nm / 243 lbf⋅ft
E 36 AMGM1043606 cm³ / 220.1 cu in272 PS / 200 kW385 Nm / 284 lbf⋅ft
400 E and E 420M1194196 cm³ / 256.1 cu in279 PS / 205 kW400 Nm / 295 lbf⋅ft"E 420" from 1993
E 500M1194973 cm³ / 303.5 cu in320 PS / 235 kW470 Nm / 347 lbf⋅ft
500 EM1194973 cm³ / 303.5 cu in326 PS / 240 kW480 Nm / 354 lbf⋅ft
E 60 AMGM1195956 cm³ / 363.5 cu in381 PS / 280 kW580 Nm / 428 lbf⋅ft

Diesel engines – specs & performance figures

ModelEngineDisplacementPowerTorqueComments
200 D and E 200 DieselOM6011997 cm³ / 121.9 cu in75 PS / 55 kW126 Nm / 93 lbf⋅ft"E 200 Diesel" from 1993
250 DOM6022497 cm³ / 152.4 cu in90 PS / 66 kW154 Nm / 114 lbf⋅ftUntil 1989
250 DOM6022497 cm³ / 152.4 cu in94 PS / 69 kW158 Nm / 117 lbf⋅ft1989-1993
E 250 DieselOM6052497 cm³ / 152.4 cu in113 PS / 83 kW173 Nm / 128 lbf⋅ftFrom 1993
250 D Turbo and E 250 TurbodieselOM6022497 cm³ / 152.4 cu in126 PS / 93 kW231 Nm / 170 lbf⋅ft"E 250 Turbodiesel" from 1993
300 DOM6032996 cm³ / 182.8 cu in109 PS / 80 kW185 Nm / 136 lbf⋅ftUntil 1989
300 DOM6032996 cm³ / 182.8 cu in113 PS / 83 kW191 Nm / 141 lbf⋅ft1989-1993
E 300 DieselOM6062996 cm³ / 182.8 cu in136 PS / 100 kW210 Nm / 155 lbf⋅ftFrom 1993
300 D TurboOM6032996 cm³ / 182.8 cu in143 PS / 105 kW267 Nm / 197 lbf⋅ftUntil 1989
300 D Turbo and E 300 TurbodieselOM6032996 cm³ / 182.8 cu in147 PS / 105 kW273 Nm / 201 lbf⋅ft"300 D Turbo" in 1989-1993 and "E 300 Turbodiesel" from 1993

Petrol engines – technical details

EngineEngine config.Forced inductionValve timingFuel deliveryDMFInlet flaps
Legend:SOHC - Single Overhead Camshaft
DOHC - Double Overhead Camshaft
VVT - Variable Valve Timing
CIS - Continuous Injection System (mechanical)
EFI - Electronic Fuel Injection
DMF - Dual-mass Flywheel (does not apply to auto. transmissions with torque converters)
M102Inline-4, 8 valvesNoTiming chain, SOHCCarburetor or KE-Jetronic (CIS)Some enginesNo
M111Inline-4, 16 valvesNoTiming chain, DOHC, VVTPort injection (EFI)YesNo
M103Inline-6, 8 valvesNoTiming chain, SOHCKE-Jetronic (CIS)Some enginesNo
M104Inline-6, 12 valvesNoTiming chain, DOHC, VVTPort injection (EFI) or KE-Jetronic (CIS, 300E-24)YesNo
M119V8, 32 valvesNoTiming chain, DOHC, VVTPort injection (EFI)Auto. trans. onlyNo

Diesel engines – technical details

EngineEngine config.Forced inductionValve timingInjection systemDMFDPFSwirl flaps
Legend:SOHC - Single Overhead Camshaft
DOHC - Double Overhead Camshaft
DPF - Diesel Particulate Filter
DMF - Dual-mass Flywheel (does not apply to auto. transmissions with torque converters)
OM601Inline-4, 8 valvesNoTiming chain, SOHCIndirect injection, in-line pumpNoNoNo
OM602Inline-5, 10 valvesNaturally aspirated or turbochargedTiming chain, SOHCIndirect injection, in-line pumpSome enginesNoNo
OM605Inline-5, 20 valvesNoTiming chain, DOHCIndirect injection, in-line pumpYesNoNo
OM603Inline-6, 12 valvesNaturally aspirated or turbochargedTiming chain, SOHCIndirect injection, in-line pumpSome enginesNoNo
OM606Inline-6, 24 valvesNoTiming chain, DOHCIndirect injection, in-line pumpYesNoNo

 

Mercedes-Benz W124 wheel sizes

Press the button below to see the original equipment manufactuer (OEM) rim & tyres sizes for the Mercedes-Benz W124. These are the original wheel sizes that were fitted by the manufacturer.

TyresRimsCentre BoreBolt Pattern
185/65 R156Jx15 ET4966.6mm5x112
195/65 R156.5Jx15 ET49 or ET4466.6mm5x112
205/60 R157Jx15 ET41 or ET4266.6mm5x112
215/55 R167Jx16 ET4666.6mm5x112
225/55 R168Jx16 ET3466.6mm5x112
225/45 R177.5x17 ET4266.6mm5x112

 

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