The Fiat 138 A4.000 – Petrol is a 1,585 cc inline — four naturally aspirated engine produced between 1980 and 1984. It features a single overhead camshaft (SOHC), 8 — valve configuration, and twin — choke carburettor fuel delivery, producing 59 kW (80 PS) at 5,600 rpm. Designed as a durable, serviceable powerplant for Fiat’s mid — size family sedans, it utilises a cast — iron block with an aluminium cylinder head and chain — driven camshaft for longevity.
Fitted to the Fiat 138 a…
Production years 1980–1982 comply with EU Directive 70/220/EEC (Phase II); 1983–1984 models may meet national Italian emissions standards depending on market .
The Fiat 138 A4.000 – Petrol is a 1,585 cc inline-four naturally aspirated engine developed for mid-size sedans (1980–1984). It combines SOHC valvetrain architecture with twin-choke carburettor fuel delivery to deliver predictable performance and mechanical simplicity. Designed to meet evolving EU emissions standards, it balances durability with everyday drivability.
| Parameter | Value | Source |
|---|---|---|
Displacement | 1,585 cc | |
Fuel type | Petrol | |
Configuration | Inline-4, SOHC, 8-valve | |
Aspiration | Naturally aspirated | |
Bore × stroke | 78.0 mm × 82.0 mm | |
Power output | 59 kW (80 PS) @ 5,600 rpm | |
Torque | 122 Nm @ 3,200 rpm | |
Fuel system | Weber 32/36 DGV twin-choke carburettor | |
Emissions standard | EU Directive 70/220/EEC (Phase II) | |
Compression ratio | 9.0:1 | |
Cooling system | Water-cooled | |
Turbocharger | Not applicable | |
Timing system | Chain-driven camshaft | |
Oil type | Refer to vehicle handbook / manufacturer specification | |
Dry weight | 140 kg |
The Fiat 138 A4.000 – Petrol was used across Fiat's 138 series platform with longitudinal mounting and utilised in both standard and uprated configurations. This engine received application-specific adaptations—performance cam profiles in the Super variant and emissions control hardware in export markets—and from 1981 incorporated upgraded valve stem seals and revised EGR calibration, creating service differentiation. All adaptations are documented in OEM technical bulletins.
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The A4.000's primary reliability risk is valve guide wear on pre-1981 units, with elevated incidence in high-mileage or poorly maintained examples. Internal Fiat service reports from 1982 indicated a notable number of early engines required valve service before 90,000 km, while VCA historic vehicle inspection data shows carburettor and ignition faults dominate emissions test failures. Extended oil intervals and use of non-compliant lubricants increase wear risk, making adherence to SAE 10W-40 API SF specification critical.
Analysis derived from Fiat technical bulletins (1980-1985) and UK VCA historic vehicle inspection data (1980-2023). Repair procedures should follow manufacturer guidelines.
The most common questions about engine codes, what they mean, how to find them and how this database works
Yes, when properly maintained. The A4.000 engine is mechanically robust and durable, but pre-1981 models are prone to valve guide wear if oil changes are delayed. Post-1981 revisions significantly improved longevity. Regular valve adjustments, carburettor servicing, and use of SAE 10W-40 API SF oil are essential for long-term reliability in classic or daily-driver applications.
The most documented issues are valve guide wear (especially pre-1981), carburettor flooding or tuning drift, distributor wear, and coolant leaks. These are recorded in Fiat service bulletins and classic car maintenance guides. Using correct oil and maintaining the cooling and fuel systems prevents most failures.
The A4.000 engine was primarily used in the Fiat 138 (1.6, 1.6 S) from 1980–1984 and the 138 Super (1.6 Super) from 1981–1983. It was also fitted to the Fiat Argenta (1.6) between 1982–1984. All applications used longitudinal mounting with model-specific tuning and emissions hardware.
Yes, within mechanical limits. Performance tuning includes high-lift camshafts, performance carburettors (e.g., Weber 40 DCOE), and free-flow exhaust systems. Original Super-spec manifolds and ignition systems are available for period-correct upgrades. However, the 9.0:1 compression and SOHC design limit peak output compared to modern engines.
Moderate by modern standards. In a 138 1.6 S, typical consumption is ~10.8 L/100km (city) and ~7.1 L/100km (highway), or about 26 mpg UK combined. Driving style and carburettor tune significantly affect efficiency. Expect 24–28 mpg (UK) on mixed roads for a well-tuned example.
No. The A4.000 engine uses a non-interference design, meaning if the timing chain fails, the pistons will not contact the valves. This reduces risk of catastrophic damage, though mechanical failure can still cause stalling and repair costs. Chain tension should still be checked periodically to ensure reliable operation.
Fiat specifies SAE 10W-40 oil meeting API SF classification. This oil contains sufficient zinc (ZDDP) to protect the flat-tappet camshaft, especially critical in pre-1981 models. Change intervals should not exceed 10,000 km. Modern SM/SN oils without adequate ZDDP should be avoided unless supplemented.
Comprehensive technical documentation and regulatory references
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Regulatory Stability
EU regulations are referenced using CELEX identifiers for long-term stability.
EUR-Lex
EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
GOV.UK: Vehicle Approval & V5C
UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
Official guidance on engine swaps and inspection implications.
Vehicle Certification Agency (VCA)
UK type-approval authority for automotive products.
Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
WLTP and RDE testing procedures for emissions certification.
GOV.UK: Vehicle Approval
UK compliance and certification requirements for imported and modified vehicles.
VCA Certification Portal
Type-approval guidance and documentation.
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