Porsche Carrera 4
The M64/05 is the last air-cooled boxer without the VarioRam intake — pure craftsmanship of the 993 era. It produces the typical boxer growl that transitions from 4,000 rpm into a tinny howl, sonically rawer and more direct than the later VarioRam engine. The power delivery is linear and good-natured, though it lacks the perceptible shove the VarioRam system delivers from about 5,000 rpm in the M64/21 — a direct comparison reveals the difference in top-end punch. It's considered absolutely reliable provided oil level and cooling air openings are maintained; the biggest risk is oil leaks, which in the worst case lead to engine failure. As a purchase it's often recommended as a more affordable entry into the world of air-cooled 911s; the difference from the VarioRam model is barely noticeable in daily driving.
All-wheel safety in the 911
285 hp flat-six with all-wheel drive. Safer than the C2 in wet and cold conditions, slightly less direct. The Carrera 4 is the all-seasons 911 for drivers who refuse to compromise on safety.
Engine Weaknesses 8
Porsche recalled approx. 20,000 vehicles (model years 1995–1996): bio-based plastic wiring harness insulation hardens, cracks under heat and vibration — short circuit and engine failure possible. Check recall status before purchase.
Symptoms: Electrical faults, engine failure, irregular injection; in the worst case a smouldering fire in the engine bay.
The plastic lower valve cover gaskets are a well-known 993 weak point. Metal press-fit inserts work loose, oil drips onto the hot exhaust system. Replace both gasket and cover.
Symptoms: Whitish smoke from the rear after motorway driving, oil traces on the rear lid and bumper, oil smell inside the cabin.
Chain case seals become porous and leak oil. Repair requires engine removal. Main cause of age-related oil loss on the 993. Address together with valve cover gaskets.
Symptoms: Oil film on underbody panelling, oil smell after extended driving, oil traces on engine block in the chain case area.
Ticking or clattering noises in the valve train, louder at idle, diminishing as RPM rises. Worn valve springs are often the actual cause rather than failed hydraulic lifters.
Symptoms: Ticking noise from the valve train, especially after cold start or at idle; noise decreases with RPM.
The DME relay fails through continuous energisation and heat. Typical breakdown scenario: starter cranks, engine won't fire. Often occurs after heat soaking (summer, full sun). At night or after cooling down the engine starts again — replace the relay first.
Symptoms: Engine cranks but won't start; no fuel pump priming noise after ignition ON; problem after heat soak.
Valve guides wear under heat and high RPM. Excessive clearance draws oil along the valve stems into the combustion chamber. The cylinder head must be removed for boring and pressing in new guides.
Symptoms: Blue smoke on overrun and when lifting off the throttle; elevated oil consumption; oily spark plugs (cylinder-specific).
The air-cooled M64 boxer consumes approximately 1 litre of oil per 1,000 km by design — up to 1.5 litres with short trips and high loads. Worn piston rings accelerate consumption.
Symptoms: Blue smoke on cold start, oil level drops regularly between services, oil smell from exhaust.
The rocker shafts sit in a press-fit without a seal ring as standard. Oil seeps at the interface between shaft and cover material. Retrofit O-ring kit (RSR motorsport part) available — 12 rings per engine.
Symptoms: Oil film in the valve cover area; oil on hot engine components; smell after a short drive.
Vehicle Weaknesses 14
Steel brake lines are particularly vulnerable to corrosion in the underbody area. Corroded brake lines are a significant safety hazard — replace completely if any deterioration is found.
Windscreen and rear window frames are prone to rust, especially if windows were replaced incorrectly. Moisture ingress and adhesive residue accelerate the attack.
Hollow sections of the rear bumper supports rust from the inside due to dirt accumulation. Regular cleaning and cavity preservation are essential.
The climate control panel can remain permanently switched on due to leakage current, draining the battery within 48 hours. Repairing the blower motor and temperature sensor is usually cheaper than a new unit.
Aluminium brake calipers corrode heavily, especially during winter use or extended storage. Pistons seize, braking becomes uneven. Rebuilding or replacement is necessary.
Steering rack tends to develop oil leaks with age. On vehicles prior to 1996 with 18-inch wheels without the factory supplement, there is a risk of steering rack fractures.
Control arm and suspension bushings age considerably. Knocking and cracking noises when compressing and steering indicate worn rubber-metal elements.
Alternator wears with age. Diodes, voltage regulator and bearing wear are typical failure causes. Rebuilt exchange units are considerably cheaper than new parts.
Hydraulic clutch cylinders leak with age. Master and slave cylinders lose brake fluid, clutch pedal sinks through to complete failure.
Central locking tends to fail due to cold solder joints in the control unit and worn actuators. Locks or unlocks immediately after the remote signal is received.
Window regulator relay clicks inconsistently. Worn cables, defective switches or damaged cable pulls are the most common causes of failures in the aged 993.
Rubber engine mounts harden with age and lose their damping function. Vibrating sensation at the gear lever and increased body vibration at idle.
Exhaust system joints corrode heavily, especially at vibration points of worn engine mounts. High heat generation and moisture in the rear section accelerate the attack.
Door hinge straps wear out, causing creaking and squeaking when opening. Heavy doors and age-related material fatigue accelerate the wear.
Reports & Tests
24 owner complaints filed with NHTSA (1993–1998). Most reported: Electrical (6), Airbags (4), Engine & Cooling (3).