Mercedes-Benz W124 (E-class 1984–1995, sedan, estate, coupe and cabriolet): common faults, maintenance guides and repair tips.
The diagnostic socket is in the engine bay next to the battery. With the engine running, connect pins 1 and 5 of the socket for about a second and cou...
Any oil that meets the Mercedes specification 235.7 is suitable; Mercedes-branded oil is not mandatory. The current viscosity is 75W-85, whereas 85W-9...
The most likely cause is a pressure accumulator (level control sphere). Its diaphragm fails, oil fills the sphere and the suspension becomes hard. A p...
The most common cause is a worn rubber flex joint (guibo) whose rubber has lost its shape and whose bolts have loosened. The propshaft centring bushin...
A noisy bearing should be replaced. The noise comes from a damaged bearing, not merely from play. A bearing can crumble from the inside without any wa...
The most common cause is too little refrigerant, either from a leak or natural loss. Typical signs are air bubbles in the sight glass and the compress...
Check the thermostat first: a poorly opening thermostat keeps the heat low. Hot enough air comes when the temperature gauge rises above 80 degrees. An...
Common places are the expansion tank cap, the top and bottom of the radiator, hose clamps, the block heater O-ring, the heater pipe O-ring and the wat...
The most likely cause is one or more broken glow plugs. The glow relay monitors the plug current and shortens the glow time according to the number of...
1. Fill the new filter with diesel and crank the engine; the air usually clears after a few attempts. 2. If the engine will not start, loosen the pres...
Blue smoke means oil is burning. The cause can be valve stem seals, worn or stuck piston rings, a leaking head gasket, late injection timing (e.g. a s...
The head bolts should be replaced, as the old ones may be corroded. In addition, the top-end gasket set is replaced and the valve guides are checked. ...
Normal ATF oil of the Dexron 2 class is used. ATF 220 is the traditional recommendation for the 722.3 and 722.4 gearboxes. Good oil is red and does no...
When hot at idle the pressure is often about 1 bar or a little below, and the manufacturer's lower limit is 0.3 bar. When revs are raised the pressure...
The old manual interval is 10,000 km, and on later W124 models the factory interval is 15,000 km. The filter is changed with the oil. In cold weather ...
Most often the alternator brushes are worn out. The brushes and voltage regulator are in the same unit at the back of the alternator, and it can be re...
Note when the light comes on. If it comes on when the parking lights or headlights are switched on, the fault is in the parking or licence plate light...
The most common causes are dried-out capacitors and cold solder joints in the control box, the brake light switch, the overvoltage protection relay, a...
The most common cause is play in the steering box (steering gear), which spoils the driving feel even if the rest of the suspension is in good shape. ...
The most common causes are worn lower control arm bushings, loose lower ball joints, the rear subframe front rubbers and the outer bushings of the rea...
A compressor is not needed for the rear springs. Lift the car, remove the wheel, place a trolley jack under the lower control arm, remove the bolts at...
The most common causes are a broken wheel speed sensor wire, dirty or rusty sensors and toothed rings, and too low an electrical voltage. The wire usu...
The most common cause is a fluid leak: the clutch fluid level is too low or the slave cylinder (on the side of the gearbox) lets the fluid past. The m...
Yes. The wires to the throttle motor and the magnetic clutch crack and become brittle along their whole length from the connector to the throttle. Aft...
The spark plug gap on the M102, M103 and M104 is 0.8 mm. Resistor (R-marked) plugs cause misfires in engines they are not intended for; for example, i...
The cause is usually fuel pressure leaking away while the car stands. The injector nipples can loosen, the cold start injector usually the most, or th...
The most common causes are vacuum leaks, for example a cracked rubber boot, the neck of the breather pipe or the O-ring of the intake air temperature ...