The Peugeot XW3S is a 1,124 cc, inline‑four petrol engine produced between 1983 and 1988. It features a single overhead camshaft (SOHC) and two valves per cylinder, delivering modest outputs suitable for its era. Equipped with a carburettor for fuel delivery, it prioritised simplicity and cost-effective manufacturing, producing approximately 45 kW (61 PS) and 88 Nm of torque.
Fitted primarily to the Peugeot 205 and 104 models, the XW3S was engineered for urban mobility and fuel efficiency in compact hatchbacks. Its character is defined by light weight and adequate low-end pull for city driving, rather than outright performance. Emissions control for its production period relied on basic engine tuning and exhaust systems to meet prevailing standards.
One documented area for attention is the carburettor's susceptibility to wear and fuel vaporisation issues, particularly in hot climates or with aged components. Service documentation from the period advises regular inspection and adjustment of the Solex carburettor to maintain optimal running and prevent hesitation or stalling, especially during warm-up or under load.
Production years 1983–1988 meet pre-Euro emissions standards as per applicable French and EU regulations of the time (UTAC Type Approval records).
The Peugeot XW3S is a 1,124 cc inline‑four petrol engine engineered for supermini applications (1983-1988). It combines a simple SOHC valvetrain with carburetted fuel delivery to deliver adequate urban performance and fuel economy. Designed to meet the emissions standards of its era, it prioritises mechanical simplicity and reliability.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,124 cc | |
| Fuel type | Petrol | |
| Configuration | Inline‑4, SOHC, 8‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 70.0 mm × 73.0 mm | |
| Power output | 45 kW (61 PS) @ 5,800 rpm | |
| Torque | 88 Nm @ 3,000 rpm | |
| Fuel system | Solex 32/32 DIDTA carburettor | |
| Emissions standard | Pre-Euro (1980s French/EU) | |
| Compression ratio | 9.3:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | None | |
| Timing system | Chain-driven camshaft | |
| Oil type | Mineral 15W-40 (API SF/CC) | |
| Dry weight | 95 kg |
The carburetted induction provides a linear throttle response but demands periodic adjustment and cleaning to prevent running issues. Using the specified mineral oil (15W-40) is important for older engine seals and bearing clearances. The timing chain is generally robust but should be inspected for slack or noise around 100,000 km. Fuel quality is less critical than for modern engines, but clean, fresh petrol is recommended. The simple design makes many repairs DIY-friendly with basic tools.
Oil Specs: Requires mineral 15W-40 meeting API SF/CC specification (Peugeot Service Manual 121). Modern synthetic oils may not be suitable for aged seals.
Emissions: Pre-Euro certification applies to all production years (UTAC Type Approval Records). No formal Euro standard existed during its production.
Power Ratings: Measured under DIN 70020 standards (Peugeot Group PT-1985). Output is consistent across model applications.
Peugeot Technical Information System: Bulletins TB-83-01, TB-85-12
Peugeot Electronic Parts Catalogue (EPC) Ref. 9615.XX
Peugeot Service Manual 121 (1984 Edition)
UTAC (Union Technique de l'Automobile) Type Approval Archives
The Peugeot XW3S was used across Peugeot's supermini platforms with transverse mounting. This engine received minor platform-specific adaptations-primarily in ancillary bracketry and exhaust routing between the 104 and 205-but remained fundamentally interchangeable. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the flat boss at the front of the cylinder block, near the gearbox flange (Peugeot Service Manual 121). The code "XW3S" will be clearly visible. Visually, it can be identified by its single-barrel Solex carburettor and distributor-based ignition system. Critical differentiation from the larger XW7 (1.3L) engine is the bore size and specific engine block casting. Ancillary components like the alternator bracket may differ between 104 and 205 applications, but the core engine is identical.
The XW3S's primary reliability consideration is carburettor maintenance, with elevated incidence of running issues in neglected examples. Peugeot service data indicates that a majority of drivability complaints for this engine family stem from carburettor faults or ignition system wear. Regular adjustment and using clean fuel make long-term ownership straightforward.
Analysis derived from Peugeot technical bulletins (1983-1988) and owner club maintenance logs. Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about PEUGEOT 121-XW3S.
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Regulation (EC) No 715/2007
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Commission Regulation (EU) 2017/1151
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