Mercedes Benz CLK 55/63 AMG Engine Replacement Compare Prices & Get Quotes

A Mercedes CLK 55 AMG or CLK 63 AMG replacement engine typically costs between £2,200 for a used M113 unit and £9,000 for a fully rebuilt M156 engine. Specialist fitting adds £800-£1,500 due to the complexity of AMG V8 systems.

• Used M113/M156 engines: £2,200-£5,500 depending on mileage and condition
• Reconditioned units: £3,200-£7,500 supply only
• Rebuilt units: £4,000-£9,000 with 12-month warranty
• Specialist fitting adds £800-£1,500; dealer labour is significantly higher
• 12-month warranty included on all rebuilt units through EnginesMarket

The M113 V8 in the CLK 55 AMG is widely regarded as one of Mercedes' most robust engines - virtually faultless with proper maintenance. The M156 in the CLK 63 AMG is more complex and less reliable, with head bolt failure being the main concern.

• M113 (CLK 55 AMG): robust, reliable, age-related issues only
• M156 (CLK 63 AMG): head bolt failure risk on early engines (pre-2010)
• M156 valve train wear and high oil consumption have been reported
• Both engines can exceed 150,000-200,000 miles with proper maintenance

The M156 engine in the CLK 63 AMG has cylinder head bolts that can break at the bolt head, allowing coolant to leak into the combustion chambers. This is a well-known issue affecting pre-2010 M156 engines.

• Symptoms: unexplained coolant loss, misfire on cold start, white smoke
• If ignored, hydro-lock can bend connecting rods and write off the engine
• Preventative head bolt replacement costs £1,800-£3,000 at a specialist
• Early detection is critical - don't wait for symptoms

Oil consumption on AMG V8s is typically due to worn valve stem seals, which harden and crack over time, allowing oil to seep into the combustion chambers.

• Blue smoke on startup is the classic symptom
• Valve stem seal replacement costs £1,400-£3,500 depending on engine
• The M113 is otherwise bulletproof - worth fixing
• Regular oil changes every 10,000 miles are critical for longevity

Well-maintained M113 V8 engines regularly exceed 150,000-200,000 miles. M156 engines can also achieve high mileage but require preventative head bolt replacement.

• M113 (CLK 55 AMG): 150k-200k+ miles with regular servicing
• M156 (CLK 63 AMG): 100k-150k+ miles with head bolts addressed
• Regular oil changes every 10,000 miles significantly extends life

On a CLK 55 AMG worth £8,000-£15,000, specialist engine replacement at £4,000-£6,000 is worthwhile if the body and interior are in excellent condition. On a CLK 63 AMG worth £25,000-£40,000+, engine replacement is almost always justifiable.

• CLK 55/63 AMG values are rising - they are future classics
• A clean, well-maintained AMG is worth saving
• Rebuilt M113/M156 engines cost £4,000-£9,000 supply only
• Compare against £10,000-£15,000 main dealer new engine quotes

The M113 in the CLK 55 AMG is significantly more reliable than the M156 in the CLK 63 AMG. The M113 is virtually faultless with proper maintenance, while the M156 has well-documented head bolt and valve train issues.

• M113 (CLK 55 AMG): robust, reliable, simpler SOHC design
• M156 (CLK 63 AMG): more powerful and rev-happy but less reliable
• The M113 is generally the more desirable engine for reliability
• The M156 is the more desirable engine for performance and sound