Porsche 911
The 930.20 is the air-cooled boxer experience in its purest form — and the most mature engine of the G-model. 3.2 litres, Bosch Motronic injection, 170 kW at 5,900 rpm. Sonically unmistakable: a dry ticking at idle, from 3,500 a throaty metallic howl that no water-cooled engine can replicate. The Motronic was a real step up from the K-Jetronic of the SC generation — better cold starts, cleaner emissions, smoother power delivery. The character remains: direct, almost raw throttle response that modern engines never had. Thermally more demanding than it looks — short trips, traffic jams and city driving are poison for head gaskets and valves. This engine wants to be warmed up properly and revved regularly. Keep up with oil changes and valve clearances, and you have one of the most durable sports car engines of the 80s.
Air-cooled, open, unforgettable
Hearing the boxer directly behind your head — the ticking at idle, the metallic crescendo on the way up — with no roof in between: acoustically unmatched. The Cabriolet is softer than the Coupe, but on a country road that doesn't matter. This is about the experience, not stiffness. Prefer late build years 1987–1989.
Engine Weaknesses 8
Due to material ageing and thermal cycling, the cylinder stud bolts become brittle and fracture. Hot exhaust gases escape between head and cylinder, damaging aluminium components.
Symptoms: Compression loss in individual cylinders, power loss, exhaust smell in the engine bay, rough engine running.
The hydraulic chain tensioners seal with O-rings that become porous with age. Oil loss in the tensioner leads to chain rattling and, if not addressed, to chain jump and engine damage.
Symptoms: Metallic rattling after cold start for 2–5 seconds until oil pressure builds; continuous rattling with advanced wear.
The Hall sensor in the ignition distributor fails without warning — engine loses ignition. No longer available as an individual part — replacement requires a complete distributor (700 €+) or specialist reconditioning.
Symptoms: Engine dies suddenly while driving; will not restart; no spark at the plugs despite a new ignition coil.
Hardened valve stem seals cause oil consumption up to 2 L/1,000 km. Engine must be removed. Typical in older units that have been driven infrequently.
Symptoms: Blue smoke on cold start and during load changes; smoke when lifting off the throttle during overrun. Oil consumption significantly elevated.
The Bosch air flow meter uses a potentiometer with a ceramic carrier. The wiper abrades the conductive track; the result is misfires, power loss and poor throttle response.
Symptoms: Engine misfires, poor throttle response, knocking noises, rough idle, occasional stalling.
The timing cover gasket hardens and begins to leak. Oil runs down the rear of the cylinders. A separate issue from the valve stem seals — often occurs together with other oil leaks.
Symptoms: Oil drops centre-rear under the car after parking; oil film on the fan housing; oil smell after driving.
Oil lines between tank, thermostat and front oil cooler seize due to galvanic corrosion (steel/aluminium). Lines can break when loosened. Preventive replacement after 20+ years is recommended.
Symptoms: Oil drops near the rear wheel arch; union nuts impossible to loosen; thermostat housing cracked during disassembly attempt.
The hydraulic clutch cylinder seals with aged rubber. Brake fluid leaks and air enters the system. Affects Carrera 3.2 from 1987 with G50 gearbox (prior to that, 915 dry clutch).
Symptoms: No gear engageable with engine running; soft or sinking clutch pedal; dropping brake fluid level.
Vehicle Weaknesses 9
Fully galvanised from 1981, but the sill connecting panel rots from inside due to trapped moisture. Floor panels and longitudinal members are also affected. Repair is very labour-intensive.
Vulnerable spots: front wings at headlight housings, rear wings at tail light clusters, and the B-pillar in the lower curved area. Rust starts from inside via moisture from the wheel arch.
Cable insulation in the engine bay becomes brittle after 35+ years. Improvised repairs from previous engine swaps accumulate. Short circuits and fire risk are real possibilities.
Control arm rubber bushings have hardened and cracked after decades. Result: imprecise tracking and increased tyre wear. Polyurethane bushings available as an upgrade.
The voltage regulator with carbon brushes fails from heat and age. Faulty diodes cause overcharging up to 17 V, damaging onboard electronics and the battery.
The steel heat exchangers rust from the inside and outside. Leaking heat exchangers direct exhaust gases into the interior — a safety issue. Stainless steel replacement is recommended.
Lead sulphate deposits and battery acid eat through the battery tray and the underlying tank support panel. Corrosion progresses invisibly between the sheet metal layers.
The brass bearing bushings in the door hinges wear out. Doors sag and close poorly. Bushings must be pressed in oversized and reamed.
Plastic bushings in the shift linkage of the 915 gearbox wear — imprecise shifter. Renewal is possible through an access panel inside the car without removing the gearbox.