Mercedes Benz SL 350/400/450 Modern Engine ReplacementCompare Prices & Get Quotes

Short summary: A rebuilt M276 engine for the SL 350 costs £3,200-£4,500 supply-only; a rebuilt M276 engine for the SL 400 or SL 450 costs £3,500-£5,500 supply-only. Fitting adds £1,200-£2,000 depending on complexity - modern V6 and turbocharged work requires specialist knowledge.

• SL 350 (M276.954): rebuilt unit £3,200-£4,500; used engine from £1,500
• SL 400 (M276.825): rebuilt unit £3,500-£5,200; used engine from £1,800
• SL 450 (M276.825): rebuilt unit £3,800-£5,500; used engine from £2,000
• M276 timing chain tensioner replacement: £800-£1,300 at specialist
• M276 oil cooler seal replacement: £800-£1,400 at specialist

Short summary: A rattling noise on cold start lasting a few seconds is the classic warning sign on the M276 V6 engine. The hydraulic secondary chain tensioners can lose oil pressure, allowing chain slack. If ignored, it can lead to more serious engine damage.

• Cold start rattle that disappears after oil pressure builds - earliest warning
• Check engine light with timing correlation codes (P0016, P0017, P0018)
• Replacing tensioners alone may not cure the rattle if VVT pins are already worn
• If caught early, tensioner replacement costs £800-£1,300 at specialist

Short summary: The M276 V6 is generally considered a reliable and well-engineered engine. It has minor common faults like oil leaks and problematic camshaft adjusters/cam followers, but it was so good that Mercedes put it in everything between 2010-2017. The M276 does not suffer from the balance shaft issues that plagued the earlier M272.

• M276 is fundamentally robust - the M272 balance shaft issues were resolved
• Timing chain tensioner rattle is the most common issue - early intervention is key
• Oil leaks from timing covers and oil cooler seals are common with age
• Regular oil changes with MB 229.5 spec oil are essential

Short summary: Properly maintained M276 engines routinely reach 150,000-200,000 miles before major work. Timing chain tensioner issues typically appear between 60,000-100,000 miles.

• M276 (SL 350/400/450): 150,000-200,000 miles with regular servicing
• Timing chain tensioner inspection recommended from 60,000 miles
• Service interval is 10,000 miles or 12 months - use Mercedes-spec MB 229.5 oil
• Late oil changes accelerate timing chain wear and oil seal degradation

Short summary: Yes, if the SL is otherwise in good condition with no rust or major transmission faults. A rebuilt M276 costs £3,200-£5,500 - far less than replacing a £15,000-£40,000 vehicle. The R231 SL's strong residual values make engine replacement a justifiable investment.

• SL 350/400/450 values: £15,000-£40,000 depending on year, mileage and condition
• Rebuilt engine with upgraded components fixes original weak points
• Supply & fit typically £4,500-£7,500 depending on engine code
• New engine includes 12-month unlimited mileage warranty

Short summary: Mercedes-Benz specifies MB 229.5 high-performance oil - typically 5W-30 or 5W-40 fully synthetic. The M276 V6 requires approximately 7.5-8.0 litres with filter.

• M276 (SL 350/400/450): MB 229.5 5W-30 or 5W-40 - 7.5-8.0L capacity
• Never use non-approved oil - can cause timing chain and hydraulic lifter issues
• Change every 10,000 miles or 12 months - stretched intervals cause timing chain wear and oil seal degradation