Problem Reports
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1997 Mercedes-Benz E420
High Usage Vehicles May Experience Ignition Lock and Tumbler Failures
Due to wear, high usage vehicles can experience ignition lock and tumbler failures. The ignition lock cylinder will generally require replacement to correct this concern.
Poor idle quality due to oil feed tubes falling into crankcase
Oil feed tubes break and fall into the crankcase (engine) and the tappet becomes noisy (ticking), resulting in degraded idle quality. Our technicians recommend replacing all of the tubes at the same time, broken or not.
Coolant Leak/Overheating Due to Radiator Leak
A coolant leak may develop form the Radiator due to degradation of its plastic components. Replacement of the failed radiator will be necessary.
Engine Oil and Coolant Leaks Resulting in Fulid Intermix
Internal and External engine oil & coolant leaks can develop from the head gasket and/or timing cover gasket; these leaks should be repaired before the engine oil and coolant intermix which can result in severe engine damage.
ABS Modulator Failure Due to Dirty Brake Fluid
As brake fluid becomes dirty over time, it can cause a failure of the anti-lock brake system (ABS) modulator assembly. Our technicians recommend a complete brake system flush every two years to help prevent this issue.
Erratic HVAC Blower Motor Operation
A malfunctioning HVAC blower motor regulator can cause the blower motor to operate below the requested speed or not at all. Updated regulators are available; the blower motor and cover need to be replaced at the same time to upgrade the system.
Check Engine Light On Due to Failed Mass Air Flow Sensor
The mass air flow sensor can fail, resulting in poor fuel economy and Check Engine Light illumination.
Check Engine Light and Engine Misfire
Failed spark plug wires and/or ignition coils can cause intermittent misfires (rough running); the Check Engine Light may also illuminate. Diagnoses of the ignition system will be necessary to determine which components are at fault.
Transmission Oil Seals May Leak on High Mileage Vehicles
High mileage vehicles may develop a leak from one or more of the transmission oil seals.
Squeaking/Worn Brake Pads May Require Rotor Replacement Also
The brakes may begin to squeak at about the 50 percent wear point. This is due to the size and material used for the brake pads and rotors. The brake rotor surfaces become uneven, causing a lip to form at the outer edge. This will generally require replacement of the rotors when the pads are worn (pad life varies depending on driving style and terrain).
Noise and/or Smoke From Drive Belt Area
The emissions air injection pump can seize, causing a loud squealing noise followed by smoke from the drive belt. If the engine is not turned off, the belt will break, turning on the alternator/battery warning light.
Throttle Valves May Experience Electrical Failure
The electronic throttle assembly may suffer an electrical failure. It is often cheaper to send the valve to a service center for repair that to purchase a new part.
One or More Instrument Cluster Display May Fail
Instrument cluster displays tend to fail, especially the clock and gear indicators; the instrument cluster needs to be replaced.
Brake Light Switch Failure May Cause ESP/BAS Warning Lights
The ESP and BAS warning lights may illuminate due to a failed brake light switch. Replacement of the failed switch should correct this concern.
Rattle From Beneath Vehicle
When the engine is running, but the vehicle is not moving, a rattle heard from beneath the vehicle could indicate that one of the exhaust catalytic converters has failed. The substrate (the internal part of the catalyst that reduces emissions) can loosen and bounce around inside the canister section of the converter—the defective unit will need to be replaced. If this problem is ignored, the substrate can break down and reduce to a size that plugs the outlet pipe, which will cause a sudden loss in power.
Spilling sticky liquids around cup holder may cause lid to stick/break
Squeak in Steering Column Due to Rubber Boot or Seal
A squeak from the steering column is often related to a rubber boot in the column or a seal in the power steering rack.
Switch For Vanity Mirror Light Above Sun Visor May Fail
The switch for the vanity mirror light above the sun visor fail; there is an updated switch for some models. On the remaining models, due to a redesign, the mirror "cassette" will need replacement.
Cracked Driveshaft Flex Discs May Cause Driveshaft Movement/Vibration
A vibration felt through the center floor of the vehicle can be caused by cracked and/or shredded driveshaft flex discs, resulting in excessive driveshaft movement. If not repaired, damage to the driveshaft center support bearing, transmission, or differential can occur.
Brake Light Not Working Due to Melted Bulb Holder Housing
Brake lamp housings can melt, resulting in a loss of contact for the brake light bulb holder. If this happens, the brake light will not work. Replacement of the damaged lamp housing should correct this problem.
Third (high) brake light housings may melt
PSE system/voice control/Tele Aid module failure may cause lack of audio/dead battery
PSE system, voice control module, or Tele Aid module failure can cause a lack of audio. These same modules can also cause dead battery conditions when they fail to "time out." Many electronic control modules are active even when the engine is off. If these modules stay active, they will drain the battery, which is why they have a timer built into the modules. The timer shuts down the modules after a preset amount of time (timing out). If a module does not time out, it will stay active and drain the battery.
Coolant Hoses May Fail Unexpectedly
The cooling system hoses may fail unexpectedly. The hoses can look good on the outside, but the rubber can degrade and erode on the inside. If not carefully checked, the hoses can burst at any time.
Premature Tire Wear Due to Cracked Lower Control Arm Bushings
Irregular and premature tire wear can be caused by the lower control arm bushings cracking, resulting excessive movement at the control arm pivot point. Ball joints can also wear out prematurely, causing similar tire wear symptoms. I some cases it may be necessary to replace the lower control arm, including bushings & ball joint to correct this concern.
Poor AC performance Due to Evaporator Temperature Sensor Failure
The evaporator temperature sensor can fail, causing the AC compressor not to cycle. If the AC compressor does not turn on, the AC system will not blow cold air. If the compressor is stuck on, the air will be very cold at first, before warming up.
The Differential May Develop Leaks From the Seals or Cover
Leaks may develop from the differential cover and/or seals on high mileage or older vehicles. Our technicians recommend a complete reseal of the differential unit if these leaks are addressed.
Shifter Lever Bushings May Break Causing Loose Feel/Noise
The bushings for the shifter lever wear out to the point where they break and fall out. This causes excessive movement (loose feel) in the shifter lever and a clanging-type noise when changing gears.