911 (Classic Air-Cooled)

1964-1989 / Coupe / Targa / Cabriolet / Germany

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

Minor Heating and Ventilation

Heat Exchanger Failure

Symptoms

Exhaust fumes enter the cabin through the heater. Carbon monoxide poisoning risk.

Cause

The 911's cabin heating works by passing fresh air through heat exchangers wrapped around the exhaust pipes. When the heat exchangers corrode and develop holes, exhaust gas mixes with the heated air.

Fix

Replace the heat exchangers.

Stainless steel replacements are available and significantly longer-lasting than the original mild steel units.

Cost: $800-$1,500 for a pair of aftermarket heat exchangers plus installation.

Cost mentioned in fix

Cost: $800-$1,500 for a

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Other known issues

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.

Common Transmission

915 Gearbox, Second Gear Synchro Wear

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.

View all 13 911 (Classic Air-Cooled) problems