Porsche Turbo S

All M44 engines are interference engines. If the timing belt breaks, the valves bend immediately — typically 8 exhaust valves. No official Porsche replacement interval; generally recommended every 30,000–60,000 km. Timing belt history is a key purchase factor.

Symptoms: Engine stops abruptly, cranks unusually fast on restart attempt (no compression resistance), metallic knocking from the head

If the balance shaft belt breaks, it can wrap around the timing belt and take it with it — causing valve damage. Always replace together with the timing belt. Oil-contaminated belts wear faster.

Symptoms: Slapping noise from the belt drive, oil traces on the balance shaft belt, engine dies suddenly

A seized water pump can cause timing belt failure — catastrophic in an interference engine. The thermostat is positioned after the radiator (not before, as is usual), which makes diagnosis more difficult. Coolant in the oil points to a head gasket failure or the side-mounted oil cooler/heat exchanger on the block.

Symptoms: Temperature gauge rising unusually, coolant loss without visible leak, milky oil on the dipstick, squealing noise from the belt drive

Same issue as the standard turbo: the electric coolant pump must continue running after switching off. With 250 hp and higher thermal load, this is even more critical. If the pump fails, the oil in the turbo bearings boils.

Symptoms: No pump noise audible after switching off, turbo whine becomes rougher, oil smoke when accelerating

The Turbo S runs at higher boost pressure than the standard turbo — the wastegate diaphragm and valve seat are under greater stress. Boost creep (uncontrolled overboost) can cause engine damage at this power level.

Symptoms: Boost pressure fluctuates, boost gauge shows overboost, power drop under partial load

All three front seals (crankshaft, camshaft, balance shaft) age together. Leaking oil contaminates the timing belt and massively accelerates its wear — that is the real risk. Replace all shaft seals at every timing belt change.

Symptoms: Oil drops under the belt cover, oil traces visible on the timing belt, oil smell when engine is warm

The 944 transaxle layout connects engine and gearbox via a torque tube — the bearings inside wear after 30–40 years. Removal is extremely labour-intensive as either the engine or gearbox must come out. Specialist refurbishment is cheaper than new OEM parts.

The 944 was fully galvanised from the factory but still rusts at weld seam edges. Sills rot from inside through the ventilation slots in the B-pillar area. Rear side panels rust when the tail light seals become brittle and water enters.

The rubber centre coupling between the engine and torque tube ages and starts rattling. Transaxle shaft bearings become noisy after 30–40 years. Clutch replacement is more involved than on conventional cars — the gearbox is at the rear.

Cold solder joints in the DME control unit, especially on early examples. Engine runs fine when warm, but cold it misfires sporadically or does not start. Resoldering by an electronics specialist is a cheap fix.