Mercedes Benz CLS Engine ReplacementCompare Prices & Save

Key points

• • CLS 250 CDI (OM651) rebuilt: £2,800-£4,500
• • CLS 350 petrol (M272) rebuilt: £2,847-£5,200
• • CLS 63 AMG (M157) rebuilt: £7,500-£12,000
• • Additional £450-£900 for supply and fit by AMG-trained technicians

Key points

• • Oil cooler seals harden and fail at 70,000-120,000 miles
• • Turbocharger can be damaged if oil contamination is ignored
• • CLS 350 CDI is considered the best diesel of C219/C218 generations
• • Preventative seal replacement costs £650-£950 at a specialist

Key points

• • Head bolt failure typically occurs between 40,000-60,000 miles
• • Symptoms include coolant loss, white smoke, and misfire on cold start
• • Preventative head bolt upgrade costs £2,200-£3,200 at an AMG specialist
• • Post-2011 cars have the updated bolt design

Key points

• • OM642 diesel regularly exceeds 250,000 miles with proper maintenance
• • OM651 four-cylinder diesel is known for 300,000+ miles on some examples
• • Most CLS cars average 8,600 miles per year
• • Only 0.8% of CLS vehicles reach 200,000 miles based on market data

Key points

• • Preventative repairs are always better value than reactive ones
• • If the bottom end is damaged, replacement is the only reliable fix
• • Specialist rebuilt engines include upgraded components addressing original failure points
• • On a CLS worth £4,000-£8,000, weigh repair cost against car's overall condition

Key points

• • CLS 350 CDI (OM642) is the "best diesel of all CLS generations"
• • CLS 350 (M276 petrol, post-2014) is very reliable with few major issues
• • CLS 350d (OM654, C257) praised as "one of the most modern diesels ever"
• • Avoid early M272 petrol engines (pre-2008) with balance shaft issues

Key points

• • EGR valve failure causes rough idle and check engine light
• • Swirl flap failure in intake manifold reduces power significantly
• • Injector seal leaks create ticking noise and diesel smell
• • With proper maintenance, OM651 can exceed 300,000 miles

Key points

• • Check for rust on subframes and rear arches before committing
• • Gearbox condition matters - 7G-Tronic and 9G-Tronic are generally robust
• • A specialist rebuilt engine includes upgraded components to prevent original failures
• • Compare the cost of replacement against buying another used CLS

Key points

• • Diesel: higher torque for towing, better motorway cruiser, AdBlue system maintenance required on BlueTEC models
• • Petrol: smoother power delivery, no DPF or AdBlue issues, lower mileage examples available
• • OM642 diesel oil seal failures are predictable and preventable
• • M276 petrol direct injection requires carbon cleaning periodically

Key points

• • 48V battery module failure affects EQ Boost function
• • Water pump leaks reported on some early M256 engines
• • Software updates resolve many electrical gremlins
• • Full engine replacement is rare - most problems stop at the 48V system