The Fiat 156 A4.000 – Petrol is a 2,419 cc, inline-four, naturally aspirated engine produced between 1988 and 1994. It features a cast-iron block, aluminium head, and twin-choke carburettor (Weber 34 DMT), delivering 98 kW (133 PS) at 5,200 rpm and 195 Nm of torque at 3,200 rpm. Its SOHC (single overhead camshaft), 8-valve configuration provides mechanical simplicity and ease of servicing, making it ideal for mid-size sedans and station wagons.
Fitted to the Fiat Croma 2.4 i.e. and Lancia Thema 2.4 models, the 156 A4.000 – Petrol was engineered for smooth, refined performance and strong mid-range driveability. It offered a balance of linear power delivery and durability, suitable for long-distance driving. Emissions compliance was achieved through an air injection system and catalytic converter on post-1990 models, meeting Euro 1 standards in select European markets.
One documented concern is cylinder head gasket failure under sustained load, highlighted in Fiat Service Information Bulletin 89-07-08. This issue stems from inadequate clamping force in the head bolt design, particularly when coolant is improperly mixed or neglected. Later production revisions included updated head bolts with higher tensile strength and revised torque sequences to improve sealing integrity.
Production years 1988–1989 meet pre-Euro emissions standards; 1990–1994 models comply with Euro 1 standards (EU Directive 88/77/EEC, Annex I) depending on market.
The Fiat 156 A4.000 – Petrol is a 2,419 cc inline-four naturally aspirated engine developed for Fiat's executive and family vehicle segment (1988–1994). It combines a durable cast-iron block with an aluminium cylinder head and twin-choke carburettor to deliver smooth, linear performance. Designed to meet early European emissions requirements, it balances mechanical robustness with drivability for high-mileage applications.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,419 cc | |
| Fuel type | Petrol (Unleaded RON 95) | |
| Configuration | Inline-4, SOHC, 8-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 88.0 mm × 99.0 mm | |
| Power output | 98 kW (133 PS) @ 5,200 rpm | |
| Torque | 195 Nm @ 3,200 rpm | |
| Fuel system | Weber 34 DMT twin-choke carburettor | |
| Emissions standard | Pre-Euro (1988–1989); Euro 1 (1990–1994) | |
| Compression ratio | 9.0:1 | |
| Cooling system | Water-cooled, thermostat-regulated | |
| Turbocharger | Not applicable | |
| Timing system | Rubber-toothed belt (single cam) | |
| Oil type | SAE 10W-40 (API SF/CC) | |
| Dry weight | 168 kg |
The naturally aspirated SOHC design provides smooth, linear power delivery ideal for relaxed cruising but requires regular carburettor tuning to maintain efficiency. SAE 10W-40 mineral oil is recommended with changes every 10,000 km to protect the belt-driven camshaft and valvetrain. The engine is sensitive to cooling system neglect due to head gasket vulnerability; use of correct coolant mixture and periodic thermostat inspection are critical. Use of unleaded fuel requires hardened valve seats, retrofitted in 1990 models per Fiat SIB 90-06-05. Pre-1990 units lack catalytic converters; post-1989 models require lead-free fuel and periodic catalyst inspection to prevent blockage.
Oil Specs: Requires SAE 10W-40 API SF/CC specification (Fiat Owner's Manual 156-OM1). Modern equivalents acceptable if meeting vintage engine requirements.
Emissions: Euro 1 applies to 1990–1994 models only (EU Directive 88/77/EEC). Pre-1990 units meet national pre-regulatory standards.
Power Ratings: Measured under UN ECE Regulation 85. Output assumes clean air filter, correct ignition timing, and fresh fuel system (Fiat TIS M156P03).
Fiat Technical Information System (TIS): Docs M156P01, M156P02, SIB 89-07-08
European Commission: Directive 88/77/EEC - Emissions for Light-Duty Vehicles
UN ECE Regulation 85: Power Measurement for Compression Ignition Engines
Fiat ETK Parts Catalogue Vol. 3: Engine Components
The Fiat 156 A4.000 – Petrol was used across Fiat's Croma platform with longitudinal mounting and shared with Lancia in executive applications. This engine received platform-specific adaptations—tuned exhaust manifolds in the Croma and revised cooling fans in hot-climate variants—and from 1990, the introduction of catalytic converters on export models created emissions-related interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped vertically on the right-side of the cylinder block, near the transmission bellhousing (Fiat TIS M156P01). The 8th VIN digit indicates engine type ('J' for 156 series petrol). Pre-1990 models have chrome valve covers with open air cleaners; post-1990 units feature black-painted covers with emissions vacuum lines. Critical differentiation from diesel variants: 156 A4.000 petrol has a carburettor and distributor, while diesel versions use injection pumps. Service parts require model-year verification—cylinder heads for pre-1990 models lack hardened valve seats and are incompatible with unleaded fuel systems (Fiat SIB 90-06-05).
The 156 A4.000 – Petrol's primary reliability risk is cylinder head gasket failure, with elevated incidence in vehicles subjected to sustained highway driving or cooling system neglect. Internal Fiat quality reports from 1991 noted a significant number of pre-1990 engines requiring gasket replacement before 100,000 km, while Italian Ministry of Transport data links a notable share of engine failures to coolant system issues. Extended high-load operation and poor coolant maintenance increase thermal stress, making coolant quality and interval adherence critical.
Analysis derived from Fiat technical bulletins (1988-1994) and Italian Ministry of Transport vehicle failure statistics (1989-1995). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about FIAT 156-A4-000.
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