Skip to content
MOTRS

911 (Classic Air-Cooled)

1964-1989 / Coupe / Targa / Cabriolet / Germany

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

Valve Guide Wear

Symptoms

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.

Cause

The valve guides are bronze alloy bushings pressed into the aluminium cylinder heads. Over 100,000+ km, the guides wear, developing clearance that allows oil to pass. The exhaust valve guides wear faster due to higher temperatures.

Fix

Cylinder head removal and reconditioning, new valve guides, new valve seals, valve lapping, and head resurfacing. Cost: $3,000-$6,000 per pair of heads (the 911 has two cylinder banks, each with its own head).

Cost mentioned in fix
Cost: $3,000-$6,000 per pair

Know something we don't?

Owned a Porsche 911 (Classic Air-Cooled)? Share your experience with this issue. What worked, what didn't, costs, tips. Help the community.

Submit an update
// More 911 (Classic Air-Cooled) problems

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.
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.
Common Transmission

915 Gearbox, Shift Linkage Slop

Vague, imprecise shifting. Difficulty finding gears, especially third and fourth.
View all 13 911 (Classic Air-Cooled) problems