Alfa Romeo 159 1.8 TBi 939

The original turbo oil feed pipe on early 1750 TBi engines lacks adequate heat shielding and runs directly alongside the exhaust manifold. The turbo operates at approximately 1,050 degrees Celsius, and the oil inside the feed pipe carbonises over time, restricting flow. A small gauze filter inside the banjo fitting at the cylinder head end can also become blocked. If oil flow is sufficiently restricted, the turbo bearings fail. Turbo failures have been reported as early as 50,000 km on cars with extended oil change intervals (35,000 km). Alfa Romeo released a revised insulated pipe (part number 55258147) that significantly reduces coking risk. Upgrading to the revised pipe costs approximately 100-150 euros including labour and should be considered mandatory on any car that still has the original pipe. If the turbo has already been damaged, a repair at a specialist turbo shop costs approximately 250-400 euros, while a full replacement turbo runs 800-2,000 euros depending on whether a standard or upgraded unit is fitted.

The M32 six-speed manual gearbox is shared with Vauxhall/Opel and other Fiat group models. The 6th gear bearing is the first to fail, producing a whining noise that increases with road speed, most noticeable in 5th and 6th gear. The 200 hp and 320 Nm from the TBi engine puts more load through the M32 than the lower-powered engines it was originally designed for. If caught early, bearing replacement at a transmission specialist costs 600-900 euros. A full rebuild with all bearings, seals, and upgraded end cap runs 1,000-1,500 euros. If the bearing disintegrates and damages the casing, a replacement gearbox costs 1,500-2,000 euros. The issue typically appears between 80,000-150,000 km. Using quality synthetic gearbox oil and changing it every 60,000 km significantly extends bearing life. Combined clutch and dual mass flywheel replacement at the same time adds approximately 800-1,200 euros.

The 159 front subframe has poor factory corrosion protection, a well-documented weakness affecting all variants regardless of engine. Stone chips remove the coating and exposed steel rusts quickly, particularly in countries using road salt. In severe cases, the subframe develops holes and becomes structurally unsafe, leading to TUV/MOT failure. Pre-2010 models without drainage holes are worst affected, which means most 1.8 TBi cars (produced from mid-2009) may benefit from the later drainage design, but this should be verified on each car. Preventive treatment with wire brushing and cavity wax costs 150-200 euros. Removing the subframe for professional powder coating costs 500-1,500 euros. A replacement subframe with parts and labour runs 1,000-1,500 euros. Cars from southern European climates are typically much less affected. This is the first thing to inspect from underneath any 159.

As a direct-injection engine, the 1.8 TBi does not spray fuel across the intake valves, so crankcase gases and oil vapour deposits are not washed away by fuel flow. Over time, carbon builds up on the backs of the intake valves, restricting airflow. Symptoms include rough cold starts, hesitation during acceleration, and slight power loss. The issue typically becomes noticeable after 60,000-100,000 km depending on driving style. Short trips and gentle driving accelerate buildup. Walnut blasting of the intake ports is the most effective cleaning method, costing approximately 200-400 euros at a specialist. Some owners report noticeable improvement in power and smoothness after cleaning. Using high-quality fuel and ensuring the PCV system is functioning correctly helps slow the buildup. Getting the engine up to full operating temperature on every journey is important.

Early 159 models (2005-2008) had a faulty power steering reservoir with a loose internal baffle that caused fluid to froth, starving the pump and accelerating rack wear. Alfa later switched from GI/E red fluid to GI/R green fluid and revised the reservoir. The 1.8 TBi was introduced in 2009 and should have the updated components, but verify the fluid colour during inspection. Even with the correct fluid, the inner rack ends are known to wear, causing knocking when turning and excessive play. A reconditioned rack costs 400-600 euros plus 200-400 euros labour. A new OEM rack runs 900-1,200 euros fitted. The individual inner rack ends can sometimes be replaced for approximately 50-80 euros in parts plus labour, though Alfa does not officially sell them separately.

The 159 is notorious for rapid front inner tyre wear, sometimes destroying tyres in under 10,000 km. The cause is a combination of aggressive factory toe-out settings and worn wishbone bushes. The upper wishbone bush fails first, producing a rattle over bumps. The lower wishbone inner bush is hollow and flexes, contributing to toe change under braking. Replacement upper wishbones (bushes are not separately available) cost 200-350 euros per pair. Lower bush replacement with Powerflex polyurethane bushes costs 200-400 euros. A complete front-end refresh with Powerflex bushes and four-wheel alignment costs approximately 500-700 euros at a specialist. This is a common repair and should be budgeted for at least once during ownership.

The plastic coolant expansion tank on the 159 is known to develop hairline cracks over time, particularly along the seams. The crack may only leak when the system is hot and pressurised, making it difficult to spot during a cold inspection. Symptoms include slow coolant loss with no visible external leak, coolant smell in the engine bay, and white residue around the tank. Replacement tanks cost approximately 30-60 euros for aftermarket or 80-120 euros for OEM. Labour is straightforward at under one hour. Some aftermarket replacement tanks have been reported as equally fragile, so an OEM part or aluminium aftermarket alternative is recommended.

The PCV (positive crankcase ventilation) system on the 1750 TBi uses a rubber diaphragm membrane inside the oil separator assembly on the valve cover. This membrane degrades over time, particularly after 10-15 years. When it fails, crankcase pressure is not properly regulated, leading to increased oil consumption, oil vapour entering the intake system, and potential boost pressure leaks. The membrane itself costs only 10-20 euros and is relatively easy to replace by prying off the plastic cap. However, other internal components of the separator (one-way valve, spring, O-ring, oil drain hole) should be inspected at the same time. Total repair with all internal components typically costs 50-200 euros at a specialist.