1991 MERCEDES-BENZ 190E 2.5-16 W201

Typical onset: 120,000-180,000 mi

Symptoms: Excessive oil consumption (1 qt per 500-1000 mi), Blue smoke on startup and deceleration, Loss of compression and power, Fouled spark plugs

Fix: Cosworth 2.5-16 engines are known for piston ring land wear and bore glazing/scoring, especially if oil changes were delayed. Requires full engine disassembly, bore honing or overbore, new pistons and rings. Budget 25-35 hours labor for a proper rebuild including machine work, plus parts. Many owners opt for short-block replacement if crank journals are also worn.

Estimated cost: $4,500-8,000

Typical onset: 100,000-150,000 mi

Symptoms: Coolant loss with no external leaks, White smoke from exhaust, Milky oil on dipstick, Overheating under load

Fix: The alloy head is prone to warpage if the cooling system fails (common thermostat or water pump issues). Head must be pressure-tested and resurfaced; expect 12-16 hours labor for head gasket replacement, plus machine shop time. If head is cracked, replacement or specialized welding adds $800-1,500.

Estimated cost: $2,200-3,800

Typical onset: 150,000+ mi

Symptoms: Knocking or rattling noise from bottom end, especially when cold, Low oil pressure at idle, Metallic debris in oil filter

Fix: High-revving Cosworth engine is unforgiving of low oil levels or poor oil quality. Bearing wear requires crank removal, inspection, and possible grinding. Often discovered during a full rebuild when chasing oil consumption. 30-40 hours labor if combined with a complete bottom-end overhaul.

Estimated cost: $5,000-9,000

Typical onset: 80,000-120,000 mi

Symptoms: Clunking when shifting from P to D or R, Excessive vibration at idle, Visible sag of transmission tailshaft

Fix: The Getrag 5-speed's rear mount deteriorates and allows the transmission to droop, causing driveline vibration and harsh shifts. Replacement is straightforward: 2-3 hours labor with transmission supported. OE-quality mounts are critical; cheap aftermarket versions fail quickly.

Estimated cost: $250-450

Symptoms: ATF or gear oil spots under vehicle near firewall, Low transmission fluid level, Burnt transmission smell if fluid runs low

Fix: The oil cooler lines (on automatic-equipped cars) or external cooler fittings corrode and weep. Manual cars can have issues with the transmission's own cooler lines at the radiator. Lines are often discontinued; expect custom fabrication or sourcing from specialists. 2-4 hours labor depending on accessibility and whether radiator removal is needed.

Estimated cost: $300-700

Typical onset: 100,000+ mi

Symptoms: Hard starting after sitting, Stumbling or hesitation under acceleration, Loss of power at high RPM, Check engine light (fuel trim codes)

Fix: The Cosworth runs KE-Jetronic fuel injection with a fuel accumulator that can fail internally, losing prime. Fuel pumps (in-tank and external) also wear. Fuel filter is often neglected; should be changed every 30k mi. Accumulator replacement: 1 hour. Fuel pump: 2-3 hours if you drop the tank. Filter: 0.5 hour.

Estimated cost: $400-1,200

Typical onset: 100,000-150,000 mi

Symptoms: Grinding or difficulty engaging 1st or 2nd gear, Requires double-clutching to shift smoothly, Gear clash when cold

Fix: The Getrag 265 dogleg gearbox is generally robust but synchros wear, especially if clutch adjustment was off or drivers forced shifts. Full transmission rebuild required: 12-15 hours labor plus synchro/slider parts. Many owners live with it or learn to double-clutch.

Estimated cost: $2,000-3,500