Skip to content
MOTRS

356

1948-1965 / Coupe / Cabriolet / Speedster / Germany

All 356 problems All workshop issues
Common Engine

Cylinder Wear and Low Compression

Symptoms

Reduced power, increased oil consumption, blue smoke under acceleration, and difficulty starting. Compression readings below 100 psi or uneven across cylinders.

Cause

The 356's air-cooled cylinders and pistons wear over time, particularly if the engine has been run without adequate warm-up, with dirty oil, or with the wrong oil viscosity. The cooling system (such as it is, an engine-driven fan and air ducting) must be intact for even cylinder temperatures. Blocked or damaged cooling tinware causes localised overheating and accelerated wear.

Fix

Cylinder and piston replacement (available in standard and oversize).

A top-end rebuild includes new cylinders, pistons, rings, valve job, and new pushrod tube seals.

Cost: $3,000-$6,000 for parts and labour.

If the crankcase is worn (main bearing surfaces), a full engine rebuild is $8,000-$15,000.

Cost mentioned in fix
Cost: $3,000-$6,000 for parts$8,000-$15,000

Know something we don't?

Owned a Porsche 356? Share your experience with this issue. What worked, what didn't, costs, tips. Help the community.

Submit an update
// More 356 problems

Other known issues

Common Engine

Oil Leaks

Oil weeping or dripping from the pushrod tube seals, rocker cover gaskets, case halves, main seal, and oil cooler connections. A warm 356 engine will have oil residue on virtually every surface.
Common Engine

Generator and Charging Issues

The red generator light stays on, the battery goes flat, headlights dim at idle. The 6-volt system (Pre-A through B T5) is particularly marginal.
Common Engine

Carburettor Issues

Rough idle, flat spots during acceleration, poor fuel economy, difficulty starting. Black smoke from the exhaust (rich running) or backfiring through the carburettor (lean running).
Minor Body and Structure

Floor Pan Corrosion

The floor pans develop rust, perforation, and structural weakness. In severe cases, you can see the road through the floor. The driver's footwell and the area around the pedal box are particularly vulnerable.
Minor Body and Structure

Heater Channel Rot

The sills (rocker panels) that run along each side of the car are actually heater channels, hollow box sections that carry warm air from the engine compartment to the cabin. They corrode from the inside out, and by the time you see external rust, the structural integrity is already compromised.
Critical Body and Structure

Battery Box Corrosion

The metal surrounding the battery in the front compartment corrodes through from acid exposure. The corrosion spreads to adjacent panels and structural members.
View all 15 356 problems