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.
Best Diesel Estate
200 hp five-cylinder diesel in the Sportwagon: strong pull, pleasant sound, good chassis. The 159 JTDM Sportwagon is the estate for high-mileage drivers.
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 8
The front subframe (engine cradle), rear axle carrier and sills rust without adequate factory protection. Particularly on TI models, areas behind trim panels corrode unnoticed. Subframe replacement costs approximately 1,000 € plus fitment.
The M32 gearbox (fitted to 1.9 JTDM and 1.9 JTS) develops bearing noise from around 100,000–190,000 km. Gearbox overhaul without removal costs approximately 1,100 €. Conversion to the more robust F40 gearbox is possible.
On the 159 and Brera 939, multiple electronic components can fail simultaneously: windows, air conditioning, Bose audio, xenon, door control units. A faulty body computer is the frequent cause. Replacement 800–2,000 €.
Control arm bushes and joints on the 159 front axle wear noticeably. A visual inspection at the time of purchase is recommended. At the end of their service life, pronounced knocking is clearly audible. Plan for renewal every 100,000–150,000 km.
The steering rack on 159 models up to 2007 tends to leak with squeaking and clicking noises when turning. A revised steering rack was fitted from the 2008 model year. A leaking rack puts stress on the hydraulic power steering.
The 159 cooling system (especially the 2.4 JTD) tends to develop air pockets, especially after repairs. Several bleed points must be observed. Symptoms: coolant boils over, heating only works at higher revs.
The 159's air conditioning regularly loses refrigerant through stone chip damage to the condenser or leaking connections. Correct fill quantity is 550 g — frequently only 490 g is added. Leaks are only visible via UV tracer after several days.
The brake discs on the 159 (especially the Spider variant) rust heavily after just 4 days of standing. Grinding and juddering occur when pulling away. After approximately 10 km the braking feel normalises, but disc wear remains elevated.
Reports & Tests
Only around 58.5 percent of seven-year-old Alfa 159s pass their MOT at the first attempt — a noticeably worse result than comparable German rivals. Diesel engines in particular cause significant problems up to and including total engine failure. Brake discs and suspension wear above average.