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Top issues
6 known problems · 3 high
high
M156 cylinder head bolt failure
high
Camshaft lobe and hydraulic lifter wear
high
ABC hydraulic suspension leaks
At this odometer
See which of this car's known problems are due at that mileage, which should already have been dealt with, and what's coming up.
Before and after
Before: Mercedes-Benz SL55 AMG (R230, supercharged 5.4L V8)
After: Mercedes-Benz SL63 AMG (R231, 5.5L biturbo M157 V8, a different engine, not covered here)
Price (AUD)
$63k-$77k (unverified)
Body styles
Roadster (folding hardtop)
Drivetrain
RWD
Origin
Germany
Built in
Germany
Overview
The 2008 R230 facelift replaced the supercharged SL55 AMG with the naturally aspirated 6.2L M156 V8 (badged 6.3), paired with AMG Speedshift MCT: a seven-speed automatic with a wet start-up clutch in place of a torque converter. It is a folding-hardtop roadster (vario roof), so there are three expensive systems to check: the engine, Active Body Control (ABC) hydraulic suspension, and the hydraulic roof. Revised ABC was standard on SL models above the SL350. Several SBC brake recalls of 2004-2005 applied to earlier R230 SLs; we could not confirm SBC on the SL63 so no SBC claim is made. The SL65 AMG (V12 biturbo) was sold alongside; the SL63 is a different car.
Engines & variants
6.2L M156 V8 (SL63 AMG, Speedshift MCT)
Engine
All-alloy naturally aspirated V8, marketed as 6.3
Engine code
Config
V8 NA
Displacement
6208cc
Power
386kW (unverified)
Torque
630Nm (unverified)
Drivetrain
RWD
0–100
4.6s
Economy
13.9 L/100km combined
Transmission
7AT (AMG Speedshift MCT, wet-clutch)
Pros
- 386kW naturally aspirated V8
- Fast, crisp MCT shifts in Sport modes
- Folding hardtop for coupe-like refinement with the roof up
- Adjustable ABC suspension and AMG drive modes
Cons
- ABC hydraulics are expensive when they leak
- Hydraulic roof adds another repair risk
- Test fuel use near 19.6 L/100km
- Cold-start jerkiness reported on MCT
Known problems
high
M156 cylinder head bolt failure
Documented M156 fault on early engines: the original head bolts can corrode or stretch and break, letting coolant into the oil or combustion chamber. Reported warning signs are a low coolant light, misfires and a check-engine lamp. A broken bolt loads the others, so failure can cascade. Enthusiast and parts-supplier sources put the affected engines as those below engine number ending 60 060658 (roughly 2006 to early 2010 builds), and an Australian reference site lists head bolt failure for the CLS63 AMG and other M156 cars. Whether a given car has been updated is not shown by the build date alone.
Fix: Ask for invoices showing the head bolts were replaced with the updated bolts. If there is no proof, budget for the job or have an M156 specialist check coolant loss, oil condition and compression before buying.
high
Camshaft lobe and hydraulic lifter wear
Owner-reported: the cam lobes (intake side most often) wear against the hydraulic lifters, and the cams are reported to be softer than the lifters. Reports put it from about 100,000 miles (about 160,000km), worse with long oil-change intervals. A US class action alleges defective cam and lifter material; those are allegations only. An Australian reference site also lists camshaft lobe and valve lifter wear for the CLS version of this engine.
Fix: Ask for a full service history with short oil intervals. Have a specialist pull a valve cover to inspect the lobes. Repair means replacing camshafts and lifters, usually at the same time.
medium
Camshaft adjuster rattle
Owner-reported: the camshaft adjusters (intake worst) lose hydraulic pressure and rattle at cold start, then at any revs. A service bulletin is said to cover it.
Fix: Listen on a cold start. Replacement of the adjusters (and normally the related solenoid seals) is the repair.
high
ABC hydraulic suspension leaks
Owner-reported and documented by an Australian recall: Active Body Control struts, lines and the pump can leak under high pressure, and a warning appears in the cluster. A September 2008 Australian recall (PRA 2008/10321) covered faulty front-axle acceleration sensors in ABC on R230 SLs, which can cause random body vibrations; we could not verify whether it covers the SL63. Replacement of a strut needs the system refilled and bled.
Fix: Look for fluid around struts and the pump, check ride height, and scan for ABC faults. Get quotes before buying; a worn car can need multiple struts and the pump.
medium
Hydraulic vario-roof faults
Owner-reported: roof cylinders can leak, the pump can fail and microswitch faults can stop the roof opening or closing.
Fix: Cycle the roof several times, check for slow or uneven movement and fluid around the boot and cylinders.
medium
AMG Speedshift MCT jerky shifting when cold
Owner-reported: some 2009 cars have hard or jerky shifts on cold start and downshifts. One owner had the valve body and wet clutch replaced without a clear result, another reported a dealer visit fixed it. No official bulletin or cost was found.
Fix: Test drive from cold. Ask for dealer records of wet clutch or software updates.