Mercedes Benz CLK 270/320 CDI Engine ReplacementCompare Prices & Get Quotes

A Mercedes CLK 270 CDI or CLK 320 CDI replacement engine typically costs between £1,000 for a used unit and £3,200 for a fully rebuilt engine. Specialist fitting adds £400-£800.

• Used OM612/OM642 engines: £1,000-£2,200 depending on mileage and condition
• Reconditioned units: £1,300-£2,800 supply only
• Rebuilt units: £1,600-£3,200 with 12-month warranty
• Specialist fitting adds £400-£800; dealer labour is significantly higher
• 12-month warranty included on all rebuilt units through EnginesMarket

Both the OM612 five-cylinder and OM642 V6 are respected diesel engines. The OM642 V6 is renowned for its smooth power delivery but has known oil cooler seal failure. The OM612 five-cylinder is a cult favourite for its distinctive soundtrack but suffers from turbocharger wear.

• OM642 V6: smooth and torquey, but oil cooler seals fail at 80k-120k miles
• OM612 five-cylinder: robust and characterful, but turbocharger bearing wear is common
• Both engines can exceed 150,000-200,000 miles with proper maintenance
• Regular oil changes every 10,000 miles are critical for longevity

The OM642 V6 engine has rubber oil cooler seals at the centre of the Vee that degrade and leak. Oil mixes with coolant or leaks externally, causing low oil pressure warnings and potential engine damage.

• Symptoms: low oil pressure warnings, oil in coolant, external oil leaks
• Repair requires intake manifold removal - labour-intensive
• Specialist seal replacement costs £700-£1,200
• If ignored, engine damage can occur - catch it early

"Black Death" is the common term for injector seal failure on Mercedes CDI engines. When the seals fail, unburnt diesel and exhaust gases escape, creating a hard, tar-like carbon buildup around the injector seats.

• Symptoms: chuffing noise from engine bay, black residue around injectors
• Affects both OM612 and OM642 engines
• Specialist seal replacement costs £250-£450
• Catch it early - the repair is far cheaper than engine replacement

Well-maintained OM612 and OM642 engines regularly exceed 150,000-200,000 miles. The OM642 can achieve 150,000+ miles with oil cooler seals replaced once. The OM612 five-cylinder is known for exceptional longevity.

• OM612: 150k-200k+ miles with regular servicing
• OM642: 150k+ miles but oil cooler seals need doing once
• Injector seal failure typically occurs from 80,000-150,000 miles
• Regular oil changes every 10,000 miles significantly extends life

On a CLK 270/320 CDI worth £2,500-£7,000, specialist engine replacement at £1,600-£3,200 is worthwhile if the body and interior are in excellent condition. However, if the car has rust, electrical issues, or poor bodywork, consider scrapping it.

• CLK values have stabilised at "rock bottom" prices
• A clean, well-maintained CLK is worth saving
• Rebuilt OM612/OM642 engines cost £1,600-£3,200 supply only
• If the car has other major issues, replacement may not be cost-effective

The OM642 V6 in the CLK 320 CDI offers more power and refinement but has the well-documented oil cooler seal weakness. The OM612 five-cylinder in the CLK 270 CDI is more characterful and robust but suffers from turbocharger wear. Both are reliable with proper maintenance.

• OM642 (CLK 320 CDI): 224 hp, smooth V6, but oil cooler seals fail
• OM612 (CLK 270 CDI): 170 hp, distinctive five-cylinder, but turbo wear is common
• Both engines can exceed 150,000-200,000 miles with proper maintenance
• The OM642 is generally the more desirable engine for performance and refinement