M112
Mercedes-Benz · 2.4-3.7L V6 NA
1997–2006
"Three-valve V6 from the last simple Mercedes era. Nothing expensive inside; the harmonic balancer rubber and the crank sensor are the two things to check. Runs for ever on synthetic oil."
Mileage Risk Timeline
When problems typically appear — enter your mileage to see your risk zone
Known Issues 7
Harmonic balancer (crank pulley) rubber delaminates
▸Rattling or knocking from the front of the engine, pulley visibly wobbling or rubber bulging forward, belt edge wear, heavier steering if the belt comes off
The rubber ring between the pulley hub and outer ring breaks up and the pulley wanders. NHTSA investigated 546 reports (PE03058, 2003-04) and closed without a recall. Caught early it is a pulley and crank bolt; missed, it grinds through the timing cover and sump and can damage rod bearings or the crankshaft. US repair quoted at $300-700 (converted approx. EUR 280-650).
Cheap insurance: have the pulley rubber inspected at every service. No Greek-specific data found.
Oil leaks — valve-cover gaskets, front crank seal (V6), rear main seal (V8)
▸Oil film on the cylinder heads and exhaust manifolds, burning-oil smell, drips at the bell housing (rear main)
Age-related gasket leaks reported by every source. Valve covers are cheap; the rear main seal on the V8 is expensive because the gearbox comes out. No EUR or km figures in any reachable source.
Normal for the age; budget for gaskets at purchase. No Greek-specific data found.
Air suspension / Airmatic failure (S/ML models)
▸Car sits low, Airmatic warning, uneven ride height
Not engine-related but very common on W220/W163. Compressor and bags fail. Can convert to springs.
S-Class and ML buyers in Greece: budget for Airmatic. Spring conversion €400-600 is popular alternative.
Oil sludge from conventional oil on long FSS intervals (MY1998-2001)
▸Thick deposits under the oil filler cap, low oil pressure warnings, history of mineral oil and 15,000+ km intervals
US class action (O'Keefe v. MBUSA, 2003): the Flexible Service System allowed drain intervals that conventional oil could not survive. Settlement extended warranty for sludge damage in the US only. Relevant today only as a service-history check.
Ask for proof of synthetic oil (MB 229.x) on early cars. No Greek-specific data found.
Crankshaft position sensor fails when hot — stall or hot no-start
▸Engine cranks but will not start when warm, stalls at idle once hot, starts again after cooling; codes P0335-P0339 (crank) or P0341 (cam)
The sensor goes open-circuit when hot. Parts only: OE A0031532828 ~EUR 125, Bosch 0261210170 ~EUR 50; labour not stated in sources. Often replaced together with the two cam sensors.
Greek summer heat is exactly the condition that triggers it. Carry a spare if the car is a daily. No Greek-specific data found.
Spark plugs + ignition coils (V6/V8)
▸Misfires, rough idle, check engine light per cylinder
V6 has 6, V8 has 8. Replace as set. Aftermarket coils available at lower cost. Simple maintenance.
Well-known service item at any Greek workshop. Budget €200-500 for full set replacement.
Coolant system: water pump, thermostat, expansion tank
▸Coolant loss, overheating warning
Plastic components age. Thermostat and expansion tank are the typical items; water pump failure is reported as recurring on both V6 and V8 (8020 Automotive, Euro Premium Parts band 100,000-180,000 mi).
Standard maintenance for age. Greek heat accelerates plastic cooling component degradation.
Models with M112 12
Related Guides
Other Mercedes-Benz Engines
Tuning Potential
N/A — classic
Frequently Asked Questions
Is the Mercedes-Benz M112 reliable?
The Mercedes-Benz M112 scores 84/100 with a verdict of BUY. It has 7 documented issues with total repair costs between €1,280 and €3,625.
What are the common problems with the M112?
The most common issues are:
- Harmonic balancer (crank pulley) rubber delaminates — high, repair cost €280–€650, N/A–N/A
- Oil leaks — valve-cover gaskets, front crank seal (V6), rear main seal (V8) — moderate, repair cost N/A–N/A, N/A–N/A
- Air suspension / Airmatic failure (S/ML models) — moderate, repair cost €600–€2,000, 100,000 km–180,000 km
- Oil sludge from conventional oil on long FSS intervals (MY1998-2001) — minor, repair cost N/A–N/A, N/A–N/A
- Crankshaft position sensor fails when hot — stall or hot no-start — minor, repair cost €50–€125, N/A–N/A
What cars use the Mercedes-Benz M112?
How much does it cost to repair the M112?
Total potential repair costs for all 7 known issues range from €1,280 to €3,625. The most expensive issue is typically Air suspension / Airmatic failure (S/ML models).
What years was the M112 produced?
The Mercedes-Benz M112 was produced from 1997 to 2006. It is a 3199cc V6 petrol na engine.
Scores are calculated from documented issues, repair costs, and failure patterns across thousands of owner reports and technical sources. Learn about our methodology. Always inspect before you buy.