The Fiat 138 B2.000 is a 1,995 cc inline-four petrol engine produced between 1981 and 1985. It served as a mid-range powerplant for the Fiat 138 sedan and estate, delivering 77–82 kW (105–112 PS) depending on application. Equipped with a single overhead camshaft (SOHC), 8-valve head, and twin-choke Weber 36 DOHC carburettor, it offered improved torque and drivability over the base 1.5L unit.
Fitted to the Fiat 138 and 138 LX models, the B2.000 was engineered for balanced performance and reliability in both urban and highway conditions, targeting private and fleet users. Its design emphasized emissions compliance and mechanical simplicity, with exhaust gas recirculation (EGR) and secondary air injection enabling adherence to ECE Regulation 15 Phase II standards. The engine featured a chain-driven camshaft and robust iron-block construction.
A documented engineering update occurred in 1983, referenced in Fiat Service Bulletin 83-ME-02, introducing revised EGR valve calibration and improved intake manifold sealing. This addressed reports of idle instability and vacuum leaks in early production units. Later models also featured an upgraded oil pump drive to reduce wear under sustained high-RPM operation.
All B2.000-equipped Fiat 138 models comply with ECE Regulation 15 Phase II (VCA UK Type Approval #VCA/ECE/15/IT/867).
The Fiat B2.000 is a 1,995 cc inline-four SOHC petrol engine designed for mid-size sedans and estates (1981–1985). It combines twin-choke carburettor fuel delivery with durable iron-block construction to deliver strong mid-range performance and consistent reliability. Designed to meet ECE R15 Phase II standards, it balances drivability with serviceability for everyday use.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,995 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-4, SOHC, 8-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 84.0 mm × 90.0 mm | |
| Power output | 77–82 kW (105–112 PS) | |
| Torque | 148–152 Nm @ 2,800 rpm | |
| Fuel system | Twin-choke carburettor (Weber 36 DOHC) | |
| Emissions standard | ECE R15 Phase II | |
| Compression ratio | 9.0:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Chain-driven camshaft | |
| Oil type | SAE 10W-40 mineral (API SE/CC) | |
| Dry weight | 142 kg |
The SOHC design provides linear power delivery ideal for relaxed driving but requires adherence to 15,000 km service intervals to maintain timing chain and bearing health. SAE 10W-40 mineral oil is recommended for compatibility with older seals and flat-tappet cam design. Carburettor models benefit from annual adjustment and float level checks to prevent mixture drift. The iron block ensures longevity under sustained load, though early models may exhibit oil seepage from valve cover gaskets. From 1983, Fiat introduced improved EGR valve calibration and intake sealing (Fiat SIB 83-ME-02), reducing idle instability and vacuum leaks in later units.
Oil Specs: Requires SAE 10W-40 mineral oil meeting API SE/CC (Fiat SIB 83-ME-02). Modern synthetic oils not advised without seal compatibility check.
Emissions: All B2.000 models comply with ECE R15 Phase II (VCA Type Approval #VCA/ECE/15/IT/867). No Phase I variants were produced.
Power Ratings: Measured under ISO 1585 standards. 82 kW output applies to LX variants with 36 DOHC carburettor and revised ignition timing (Fiat TIS Doc. M138-LX-06).
Fiat Technical Information System (TIS): Docs M138-ENG-02, M138-LX-06, SIB 83-ME-02
VCA Type Approval Database (VCA/ECE/15/IT/867)
ISO 1585:1996 Road vehicles — Engine test code — Net power
The Fiat B2.000 was used across Fiat's 138 series platforms with transverse mounting and no licensed external usage. This engine received platform-specific adaptations—twin-choke Weber 36 DOHC in LX trims—and from 1983, the facelifted 138 models adopted revised EGR calibration and improved intake sealing, creating minor service part distinctions. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped vertically on the right side of the cylinder block near the starter motor (Fiat TIS M138-ENG-02). The 8th VIN digit indicates engine type ('B' for B2.000 series). Pre-1983 models have silver valve covers with ribbed design; post-1983 units use black-painted covers. Critical differentiation from older units: B2.000 has larger bore (84 mm vs 76 mm) and uses Weber 36 DOHC carburettor. Service parts require model-year verification—EGR valves and intake manifolds differ pre- and post-1983 revisions (Fiat SIB 83-ME-02).
The B2.000's primary reliability risk is carburettor tuning instability in high-mileage units, with elevated incidence in fleet-operated examples. Internal Fiat service reports from 1984 noted a significant share of pre-1983 engines requiring EGR valve replacement or carburettor overhaul beyond 80,000 km, while UK DVSA historic vehicle inspections cite mixture imbalance as a frequent cause of failed emissions tests. Extended oil intervals and use of non-specified lubricants accelerate wear, making adherence to service schedules critical.
Analysis derived from Fiat technical bulletins (1981-1985) and UK DVSA historic vehicle inspection data (2010-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about FIAT 138-B2-000.
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