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Mercedes-Benz ML350 Problems

RepairPal has identified the most common problems with the Mercedes-Benz ML350 based on complaints from actual vehicle owners. We'll tell you what the problem is and what it'll take to fix it.

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44
Known Problems

Motor mounts commonly fail, causing engine vibrations to be transferred to the body. Failed motor mounts should be replaced in order to prevent damage to the transmission mount.

The engine in the 2006-2008 Mercedes Benz ML350 is known by Mercedes Benz to have issues due to a poorly manufactured gear on the balance shaft (also known as the counter-rotating assembly). Since the balance shaft gear is driven by the timing chain, which keeps the engine rotating synchronously, when it fails, the timing of the engine will change causing:

-Illumination of the Check Engine Light

-Rough Running Conditions

-Stalling

-Loud Rattle or Slapping Noise

-OBD Trouble Code P1200 and P1208

Correction for this issue is replacement of the balance shaft, or balance shaft gear. Replacement of the timing chain and tensioner should be done as well. The Mercedes Benz dealer may cover some or all of the repair cost on select vehicles as a result of a class action settlement.

The engine may develop a stalling and/or no start condition due to a failed crankshaft position sensor.

The mass air flow (MAF) sensor tends to fail. The engine air filter should be replaced when the mass air flow sensor is replaced; a dirty filter can allow debris to damage the new sensor.

The 2006-2012 Mercedes Benz ML350 may have engine oil seeping or leaking from the back of the cylinder heads. This is commonly misdiagnosed as leaking valve covers.

On the back of the cylinder heads there are three, in total, plastic expansion plugs that plug access ports to the camshafts. These plugs are well known for seeping oil, and leaking if left unattended. The oil will run down the back of the engine and eventually make it to the ground. 

Replacement of these three plastic plugs is extremely simple, and should be done as regular maintenance. The recommended interval for replacement is every 60,000 miles.

The rubber bond in the harmonic balancer can decay, which causes the balancer to move and work its way toward the timing cover. If the balancer comes into contact with the timing cover while the engine is running, it will fracture and damage the cover and potentially other surrounding parts. The harmonic balancer should be inspected at every service.

An engine Oil leak may develop from the PCV vent housing on the valve cover and/or the inspection plate on the front of the engine.

The electrical connector at the automatic transmission may leak fluid into the wiring harness. If not repaired, the oil will migrate through the wiring harness and damage the transmission control module. At that point, a new harness and control module may be necessary to correct this problem.

The ESP and BAS warning lights may illuminate due to a failed brake light switch. Replacement of the failed switch should correct this concern.

High mileage or older vehicles commonly develop leaks from the differential seals and/or cover. Our technicians recommend a complete reseal of the differential unit whenever these leaks are repaired.

The camshaft adjuster solenoid (which is related to the variable valve timing system) may fail or timing chain/balance shaft components may wear, resulting in illumination of the Check Engine Light and various drivability issues. Mercedes-Benz has released a service bulletin outlining specific repair instructions depending on fault codes stored.

Vehicles equipped with a 7-speed automatic transmission may develop a rough shifting condition, most commonly going up from first to second gear and going down from third to second or second to first gear. Our technicians tell us this is due to an internal component failure. Mercedes has released updated parts; the transmission will need to be removed and disassembled to complete the necessary repairs.

The brake light warning message for a burned out bulb may be displayed. Our technicians tell us the tail lamp housing may melt and distort causing a poor connection at the bulb. The lamp housing should be replaced to correct this condition.

Release cables for the rear seat (second row of seats) tend to stretch or break requiring replacement.