Alfa Romeo 2.4 JTDM
The 2.4-litre JTDM five-cylinder in the 159, Brera and Spider — 200–210 hp in the strongest version, the most powerful diesel in the Alfa range of its era. 400 Nm of torque pushes the heavy 159 or the Brera Q4 forward with authority. The five-cylinder sound is odd and unmistakeable — neither the clatter of a four nor the smoothness of a six, but something in between. In the Spider with Q4 all-wheel drive, an unusual but practical all-round combination.
Open-Top Diesel Pleasure
200 hp diesel in the Spider 939 — an unusual combination, but the open body elevates even the diesel. Powerful, economical, unmistakable.
Engine Weaknesses 6
The dual-mass flywheel on the 2.4 JTDM wears at high mileage and with short-trip driving.
Symptoms: Vibrations when pulling away, rattling when declutching, rough idle
Soot deposits from EGR coke up the intake manifold. The high-output version of the 2.4 JTDM (210 hp) is also affected.
Symptoms: Power loss, black smoke, swirl flap risk
DPF clogs with predominantly urban driving. Regular motorway runs are required for regeneration.
Symptoms: Engine warning light, power loss, elevated fuel consumption, limp mode
Identical design issue to 939B1: the O-ring gasket between oil pump and oil sump flange hardens thermally. Brief oil pressure drop after cold start. Known at Alfa but not officially communicated. Aluminium O-ring as permanent fix.
Symptoms: Brief oil pressure warning tone after cold start (approx. 3 seconds), then normal operation
The swirl flap system of the 2.0 JTDm 939A9 shares the structural problem of all JTDm variants. EGR soot deposits cause flaps to stick; linkage bushes wear out. Blanking kit or revised manifold as permanent solution.
Symptoms: Engine warning light, power loss, stumbling in the lower rev range
The alternator on the 2.0 JTDm shows bearing wear and freewheel failure at higher mileages. Documented in Alfisti Forum for the 2.0 JTDm Brera/159. Replacement is labour-intensive due to tight packaging.
Symptoms: Whistling at certain rev ranges, battery drain while driving, battery or alternator warning light
Vehicle Weaknesses 4
The electric folding hood of the Spider 939 has known weak points: plastic gears in the flap motors break, hydraulic fluid becomes contaminated with water. Control units no longer available. Repair: €1,500–3,000, aftermarket aluminium gears approx. €85.
Brake discs on the Spider 939 rust extremely fast after short standstill periods (even 4 days). Seized discs cause significantly extended stopping distances and loud grinding. Returns to normal only after approx. 10 km of driving. Particularly problematic for infrequently used convertibles.
The Spider 939 shares with the 159 and Brera the weakness of leaking A/C condensers caused by stone chips. Refrigerant escapes slowly, only detectable via UV tracer after several days. Condenser replacement €300–600, A/C service €60–100.
The Spider 939 (1.9/2.0 diesel) has known power steering problems caused by a dislodged sleeve in the intake port that draws in air. A revised reservoir (51880990) with green Tutela GI/R fluid fixes the issue. Cost: €35–400.