Common Problems W124 E Class

Dan9th February 2017

Problems and Faults with the W124 E Class

The 124 E Class was built from 1985 to 1996 and is a legend in the Mercedes history due to sheer over engineering and reliability. For this reason, you still see them on the roads with enthusiasts either using them as work horses or show cars. The engines in the 124 E Class varied from the M102.963 1996cc to a M119 5786cc but the majority of the W124’s on UK never saw engines bigger than a 3199cc M104 unless imported from Japan or had a custom conversion.

The 124 E Class comes different variants such as the Saloon, Coupe, Estate, Convertible and Limos. Many UK Mercedes drivers choose the W124 as their daily car because of reliability, easy DIY, cheapness and safety. The W124 is renowned for its extremely high build quality that makes it as reliable as it is today but it does have some issues that we shall discuss. However, with the W124, replacement parts are easy to come by and the great thing is that you will be able to fix the majority of things yourself. Prices are currently still reasonable, however expect these to shoot up as the W124 is a Future Classic Car, which will increase in value as time goes on.

Common Reliability Problems

Moisture in Distributor Cap. If left standing for weeks on end, moisture can build up inside, which makes the car hard to start and splutter. When replacing the distributor (and rotor arm), you should always stick to either Bosch or Mercedes parts.
Rear Window Delamination. Coupes suffer from delamination and a milky colour appear around the edges.
Wiring Loom Biodegradable. Found in facelift models (220, 280, 320) the wiring loom biodegrades and yes, it will be expensive to fix.
Head Gasket Failure. Symptoms such as oil leaks, foamy coolant and using a lot of water.
Over Protection Relay Failing (OVP). Car will intermittently start and cut out as well as many other odd failures.
Rust. Not as bad as the W210’s but the rust to watch out for is around all arches, rear sills around the jacking points, cross member below the sump and the front mounts of the rear sub frame.
Fuel Pump Failure. A weak pressure from the fuel pump can starve the engine of fuel, therefore it won’t run as it should, always use Bosch Fuel Pumps as replacements.
Estate Rear Quarter Window. Water gets trapped in the path where the window seal resides and causes severe rust to appear and is very common, so check the seals.
Window Regulators. The coupes in particular love breaking the regulators, which causes a jam when putting up the window.
Vacuum Leak. Will cause various issues including rough idling/hunting, sloppy gear changes and various other things, check the OVP, battery and fuses.
Ignition Barrels. Symptoms are that you are unable to turn key to position one and it is recommended changing the barrel before they break as they are even harder to change when it won’t move.
Sunroof Seals. Due to age, the seals perish that will allow water to build up.
Rear Wiring Harness on Estates. with the continual flexing of the wires when the boot is opened and closed, it causes the wiring to breakdown, which leads to the inevitable.
Self Leveling Suspension Spheres on Estates. Symptoms are that the ride is incredibly hard at the rear and not “bouncy”.
Front Ball Joints. Symptoms are a “clunking” noise when pulling of or turning a corner and when replacing, you should change them as pairs for peace of mind.
Bosch KE Jetronic Metering Unit. Due to old age, these may start to break down and not release as much pressure as they should, but check the fuel pumps before changing this part.

The reliability problems of the 124 E Class may seem a little scary, however apart from the wiring loom and head gasket failures, the rest are pretty much DIY with the correct tools. The list is rather long due to the fact I have owned three and different variants (estate, saloon, coupe) suffer from different problems. Before buying a W124 be sure to check all these points as they may empty your wallet later on. I personally own a W124 300CE and a 320 CE Convertible and previously owned a 230CE and in all three cases the first thing I change is the OVP relay with a genuine part from Mercedes due to the problem that occur with a faulty one.

W124 Modifications and AMG Upgrades

Most W124’s will ride quite high with tractor like suspension and many people decide to slightly lower the car with springs but forget about changing the shock absorbers. This causes a “crashy” ride as well as irregular tyre wear but the best shock absorbers for the W124 would be the Bilstein’s. Owning a classic car from the W124 series requires knowledge, therefore its important to read up well with books such as the “The Complete Story” and of crouse, you cannot go wrong with the basic Haynes manual.

If you are on Facebook, there is an excellent Facebook Group called “W124 Enthusiasts” which is a closed group run by knowledgeable 124 owners that are more than happy to answer questions and of course post great content.