Recalls: Mercedes A209 CLK 55 and CLK 63 AMG
Overview
Manufacturers, or importers, issue recalls for defects or faults which have the potential to cause injury. Generally, manufacturers will inform the original buyers if their vehicle is subject to a recall and of the steps required to remedy the defect or fault. Please note that the recalls below (if any) are for Australian-delivered vehicles only. Furthermore, the number of recalls should not be taken as an indication of a model’s reliability or its safety more generally.
Recalls: Mercedes A209 CLK 55 and CLK 63 AMG
- In March 2004, a recall was issued for Mercedes A209 CLK Cabriolet vehicles manufactured between August 2003 and October 2003 due to the possibility that the tongue of the seat belt may not belt may not fully engage in the seatbelt buckle (PRA 2004/6890).
- In September 2004, a recall was issued for Mercedes A209 CLK Cabriolet vehicles due to potential component failure of wiring in the side airbags, requiring rectification of the pin allocation (PRA 2004/7221).
Problems and faults: Mercedes A209 CLK 55 and CLK 63 AMG
Overview
This section identifies potential problems, causes and fixes based on the experiences of owners and repairers, online sources and technical service bulletins. This information is provided solely for reference purposes and AustralianCar.Reviews recommends that only properly qualified persons carry out repairs or modifications. Furthermore, the number of items below should not be taken as an indicator of a model’s reliability or the frequency with which they may occur.
To report a problem or fault to the AustralianCar.Reviews team, please use the Contact Us form. Note that AustralianCar.Reviews does not offer advice on automotive problems or disputes; such enquiries will not receive a reply. For vehicles purchased from dealers after 1 January 2011, please see our Australian Consumer Law fact sheet.
M156 engine (CLK 63 AMG): cylinder head bolt failure
For 6.2-litre M156 engines with engines numbers up to 1569xx 60 060658 (corresponding to engines produced from 2006 to the first half of 2010), the cylinder head bolts can stretch and snap.
The M156 engine has ‘torque to yield’ bolts which are designed to achieve a specific clamping pressure by being tightened to a specific torque and then turned a specific number of degrees. To achieve the intended clamping pressure, the upper section of the bolts is designed to stretch slightly. While the exact cause is unclear, it has been suggested that the design of the bolts, their metallurgy or corrosion causes them to stretch and snap.
The failure of one head bolt puts additional stress on the other bolts, causing further failures. The loss of clamping pressure allows coolant and oil to enter the combustion chamber; coolant can also be forced up through the failed head bolt locations into the top of the heads, causing white smoke and a rough idle. In severe cases, the cylinders can experience hydro lock, causing the piston to seize and destroying the entire engine.
Symptoms of head bolt failure are:
- Repeated low coolant levels;
- High oil level (from coolant getting into the oil);
- Illumination of the check engine light (CEL); and,
- White exhaust smoke (burning oil).
To test for head bolt failure, the coolant system could be pressurised and allowed to sit over night to see if the coolant level had dropped and if coolant was present in the oil.
In April 2011, Mercedes-Benz issued service bulletin LI01.30-P-051567 regarding broken cylinder head bolts for the M156 engine which caused coolant to enter the engine oil and/or the combustion chamber. The service bulletin identified the following symptoms:
- CEL (Check Engine Light) illumination;
- Misfire;
- Rough running; and,
- Low coolant indicator illumination.
To fix, the cylinder heads had to be removed so that the piston deck height could be measured. If the measurement from the top surface of the crankcase to the top surface of the piston was outside of specification (the maximum deck height was 0.23 mm), then the affected connecting rod with piston and bearings had to be replaced. As part of the repair, all cylinder head bolts and hydraulic tappets were to be replaced.
M156 V8 engine (CLK 63 AMG): camshaft lobe and valve lifter wear
In a US class action – CEDRIC CHAN v. DAIMLER AG, MERCEDES-BENZ, MERCEDES-BENZ USA, LLC and MERCEDES-AMG GMBH – it was alleged that the combination of nodular cast iron camshafts and valve lifters made of 9310-grade steel resulted in premature wear of the M156 engine as a result of:
- the soft camshaft metal, and/or
- improper heat treating, and/or
- improper camshaft offset.
Specifically, the camshafts were designed so that the lobes would contact the valve lifters. When the camshaft lobes experienced wear, the surface would become rough or scored and no longer make contact with the lifters with the same precision – this would cause the lifters to wear prematurely, demonstrated by a gouged ring in the top of the valve lifter. The gouged ring wear on the buckets also indicated that the buckets were not spinning as intended. The result of this premature wear would be serious engine failure.
Symptoms of camshaft lobe and valve lifter wear include rattling or clattering noises on start-up. In service bulletin S-B 05.20/20b (produced in 2009), Mercedes-Benz acknowledged the problem of camshaft and valve tappet wear. Ultimately, the class action did not proceed due to the plaintiffs’ lack of standing.
Problems and faults: Mercedes A209 CLK 55 and CLK 63 AMG
- The convertible roof may jam when lowering due to a faulty hydraulic cylinder that requires replacement with a redesigned unit.
- The boot may not open due to a faulty switch for the convertible roof mechanism.
- Rumbling or squealing noises from the air conditioning compressor may be due to a faulty pulley or bearings; improved components were subsequently released.
- The alternator may not adequate recharge the battery due to a defective internal voltage regulator.
- The air conditioning (blower) motor may stop working or only work intermittently due to an internal circuit breaker in the air conditioning (blower) motor regulator that requires replacement.
- A whistling or squealing noise from the brakes as they are released may be due to a fault with the brake booster.
- The cruise control function may not operate if all four tyres are not the same size or due to a lack of rotation.
- The horn may independently sound due to inadequate clearance between the horn contacts and the airbag assembly in the steering wheel.
- The power adjustable front seats may stop working due to the seat control module failing.
- The rear head restraints may not lock due to a faulty actuator.
- The tail-light bulbs may burn-out prematurely; this may be fixed by installing a jumper harness with greater resistance that reduces the voltage by one volt.
- Transmission fluid may leak from the electrical connector and travel through the wires to the transmission control unit; if so, the connector and O-rings will need to be replaced.
