911 (Classic Air-Cooled)

1964-1989 / Coupe / Targa / Cabriolet / Germany

All 911 (Classic Air-Cooled) problems All workshop issues

Common Transmission

915 Gearbox, Second Gear Synchro Wear

Symptoms

Second gear crunches or grinds on downshifts, especially when cold. The synchro cannot match shaft speeds before gear engagement. Over time, it worsens and eventually grinds on upshifts as well.

Cause

The 915 gearbox's second gear synchro takes the most punishment in normal driving. The synchro ring is brass and wears against the steel gear cone. Heavy-handed shifting and infrequent oil changes accelerate the wear.

Fix

Gearbox rebuild with new synchro rings.

The gearbox must be removed from the car.

Cost: $3,000-$6,000 at a specialist.

Cost mentioned in fix

Cost: $3,000-$6,000

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Other known issues

Common Transmission

915 Gearbox, Shift Linkage Slop

Vague, imprecise shifting. Difficulty finding gears, especially third and fourth.

Minor Engine

Cam Chain Tensioner Failure (3.2 Carrera)

The cam chain tensioner fails, allowing the duplex timing chain to go slack. The chain skips teeth on the sprockets, the camshaft timing shifts, and the valves collide with the pistons. The result is catastrophic, bent valves, damaged pistons, and potentially a cracked cylinder head.

Common Engine

Valve Guide Wear

Blue smoke from the exhaust on start-up (oil pooled on valve heads drains into the combustion chamber) and on the overrun (oil drawn past the guides by manifold vacuum). Increased oil consumption.

Critical Engine

Oil Leaks, The Usual Suspects

Oil residue on every surface of the engine. Active dripping in the garage.

Critical Engine

2.7-Litre CIS Engine, Nikasil Cylinder Scoring

Increased oil consumption, loss of compression, rough running, and blue exhaust smoke. The engine gradually loses power and efficiency.

Common Engine

Thermal Reactor Exhaust Damage (1975-1977)

Exhaust valve recession, burnt valves, cracked exhaust studs. The thermal reactor runs extremely hot to burn unburned hydrocarbons.

View all 13 911 (Classic Air-Cooled) problems