Spot the grot
… where bills lurk on the CL
around £1000 per side, though once replaced they rarely need doing again. Pre-facelift CL600S had cylinder deactivation that shuts down six cylinders when cruising, to boost economy. The system can fail causing a misfire so most had this feature removed by recoding the ECU.
Superchargers and turbos are reliable if the oil is renewed every year or 12,000 miles. Engine bay heat can also kill starter motors but a reconditioned Bosch unit costs £190 and a Lucas is £135. If the engine spins over but won’t fire its likely to bea duff crankshaft sensor. Budget around £250 to fix.
All CLS came with an automatic ’box. The V8s was usually a five-speed; the CL600 initially got a four-speed but an extra ratio was added with the facelift in 2002. From September 2003 the CL500 featured a seven-speed auto that sadly isn’t quite as reliable as its bullet-proof predecessor. All transmissions are tough, but the five-speed unit can suffer oil leaks. A wiring harness runs from the ECU to the gearbox and the 13-pin connector for this contains an O-ring which leaks oil and then contaminates the ECU. A new O-ring every five to ten years will stop problems; once oil gets into the ECU things get very expensive.
On the 7-Gtronic seven-speed transmission, the conductor plate gives problems. This is the electrical unit on top of the valve block inside the gearbox. The electrics can short-circuit which leads to gearshift problems and the only fix is a new conductor plate at about £1000.
Rear axles are unbreakable but the steering can give problems. It’s assisted by a dual pump that also powers the computer-controlled hydraulic
suspension, which has a reputation for expensive failure. The C215 was the first Mercedes with this system, called Active Body Control (ABC). While components can fail, it is lack of maintenance or use that cause most problems. The front ABC struts have the lower balljoints built in so a simple wear and tear item can become expensive – refurbished items cost around £500 apiece. If the car hasn’t had a new dual pump it’ll probably need one at £1000 supplied and fitted; they rarely last more than 60,000 miles. When the pump fails, a bearing can disintegrate and contaminate the system with fine metallic particles; the only effective fix is to clean everything or replace parts, or the particles will get lodged in the valves and suspension hydraulic units. The system ensures
a supple ride with minimal wallow in the bends. New Mercedes parts are extremely costly, but reconditioned bits are much more affordable.
The ABC pipes that connect the suspension can corrode as they are hidden by undertrays that should be in place to aid high-speed aerodynamics. Check that the undertrays are there and inspect the high-pressure pipes for corrosion.
Much less serious are worn bottom arm and balljoint bushes as they’re cheap and easy to repair. Most mechanical parts are shared with other Mercedes models, but the CL’S weight means some parts will need to be replaced more often.
The brakes tend to be reliable. AMG editions got more complicated (multi-piston) calipers so are more expensive to refurbish. Disc and pad replacement is more likely. It’s costly but not
prohibitively so. Some cars feature 19in wheels that can crack on their inner rim if the car is regularly driven over broken road surfaces. Repairs are possible or refurbished items cost around £350 apiece; new ones are £3000 per set.
Trim and electrics
Leather trim was standard, while the CL600 got a softer, luxurious Nappa alternative. The leather, carpet and headlinings are very durable unless the car has mega mileage.
The CL has numerous electronics including Brake Assist, ESP, and multi-media system plus sat-nav that can be speech controlled. Bi-xenon headlights are standard while some have built-in TV and adaptive cruise control. All CLS have climate control, parking sensors, electric adjustment for heated front seats, windows, mirrors and steering wheel plus heated windscreen washer jets. Later options include ventilated front seats, an integral phone or electrically operated rear window blind.
Electrical problems are common, especially door component failure once the loom has been damaged between bodyshell and door, so make sure you check the self-closing mechanism and central locking. Electronics can give problems and it’s best to use a specialist equipped with the official Star diagnostic system.