Mercedes Benz SL 280/350 Petrol Engine Replacement Compare Prices & Get Quotes

Short summary: A rebuilt M104 engine for the SL 280 costs £2,200-£3,200 supply-only; a rebuilt M272 engine for the SL 350 costs £2,800-£4,500 supply-only. Fitting adds £800-£1,500 depending on complexity - V6 work requires specialist knowledge.

• SL 280 (M104.943): rebuilt unit £2,200-£3,200; used engine from £1,200
• SL 350 (M112.923): rebuilt unit £2,500-£3,800; used engine from £1,400
• SL 350 (M272.967): rebuilt unit £2,800-£4,500; used engine from £1,500
• SL 350 (M276.952): rebuilt unit £3,200-£4,500; used engine from £1,800
• M272 balance shaft replacement: £2,400-£3,600 at specialist

Short summary: A rattling noise on cold start lasting a few seconds is the classic warning sign on the M272 V6 engine. If ignored, it can lead to catastrophic engine failure. M272 engines with engine numbers below 2729..30 468933 require updated balance shaft parts per Mercedes TSB.

• Cold start rattle that disappears after oil pressure builds - earliest warning
• Check engine light with timing correlation codes (P0016, P0017)
• Metallic swarf in engine oil indicates balance shaft gear wear
• If caught early, balance shaft replacement costs £2,400-£3,600 at specialist

Short summary: The M104, M112, M272 and M276 engines are all fundamentally refined and durable, but each has well-documented weaknesses. The M104's biodegradable wiring harness affects 1993-1995 models, while the M272's balance shaft wear is a known catastrophic failure. With these addressed, all are capable of 150,000+ miles.

• M104 inline-six is smooth but wiring harness vulnerability is critical
• M112 V6 is robust but harmonic balancer failure is age-related
• M272 V6 balance shaft wear is the most critical failure point
• M276 V6 timing chain tensioner wear affects cold starts
• Regular oil changes with MB 229.5 spec oil are essential

Short summary: Properly maintained M104, M112, M272 and M276 engines routinely reach 150,000-200,000 miles before major work. Balance shaft issues on the M272 typically appear between 60,000-90,000 miles.

• M104 (SL 280): 150,000-200,000 miles with regular servicing
• M112 (early SL 350): 150,000-200,000 miles with proper maintenance
• M272 (SL 350): 150,000-200,000 miles - balance shaft inspection from 60k miles
• M276 (SL 350): too early for definitive data - tensioner issues from 60k miles

Short summary: Yes, if the SL is otherwise in good condition with no rust or major transmission faults. A rebuilt M104 costs £2,200-£3,200 - far less than replacing a £5,000-£15,000 classic. The SL 350's higher value (£6,000-£30,000) makes replacement even more justifiable.

• SL 280 values: £5,000-£15,000 depending on condition
• SL 350 values: £6,000-£30,000 - strong values for well-maintained examples
• Rebuilt engine with upgraded components fixes original weak points
• Supply & fit typically £3,000-£6,000 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 M104 requires approximately 6.5 litres; the M112/M272/M276 V6s require approximately 7.5-8.0 litres.

• M104 (SL 280): MB 229.5 5W-30 or 5W-40 - 6.5L capacity
• M112/M272/M276 (SL 350): 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