The Citroen 150D (XY7) is a 1,450 cc, inline-four naturally aspirated diesel engine produced between 1972 and 1980. It was developed as a fuel-efficient alternative for commercial and passenger variants of the Citroen Ami and Dyane platforms, featuring indirect injection and a mechanical fuel pump. In standard tune it delivered 27 kW (37 PS), providing modest power with excellent fuel economy and long service life under proper maintenance.
Fitted primarily to the Citroen Ami 8 and Dyane 6 Décalée, the 150D was engineered for economical urban delivery use and basic transportation, prioritizing simplicity and ease of repair. Emissions compliance was managed through basic combustion tuning and exhaust routing, meeting early pre-Euro standards typical of light commercial vehicles in this era. Its compact size and front-wheel-drive layout supported lightweight vehicle packaging.
One documented reliability concern is cylinder head warping under sustained load or inadequate cooling, highlighted in Citroen Service Bulletin SB 73/089. This issue stems from thin-cast aluminium heads prone to distortion when coolant levels are low or thermostat function is compromised. From 1976, revised head gasket material and improved cooling system design reduced warping incidence in later production units.
Production years 1972–1980 meet pre-Euro emissions standards (VCA UK Type Approval #VCA/EMS/1122).
The Citroen 150D (XY7) is a 1,450 cc inline-four naturally aspirated diesel engineered for lightweight commercial and passenger vehicles (1972–1980). It features indirect injection and a mechanically governed fuel system, delivering modest output with strong fuel economy. Designed for simplicity and durability, it supports high mileage when maintained with correct lubricants and cooling system care.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,450 cc | |
| Fuel type | Diesel | |
| Configuration | Inline-4, OHV, 8-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 76.0 mm × 80.0 mm | |
| Power output | 27 kW (37 PS) @ 4,200 rpm | |
| Torque | 72 Nm @ 2,000 rpm | |
| Fuel system | Mechanical indirect injection pump (Bosch M-System) | |
| Emissions standard | Pre-Euro | |
| Compression ratio | 22.0:1 | |
| Cooling system | Air-cooled | |
| Turbocharger | None | |
| Timing system | Gear-driven (no service interval) | |
| Oil type | Total Méga 20W-50 | |
| Dry weight | 89 kg |
The 150D's air-cooled design eliminates coolant-related failures but requires unobstructed airflow and clean cooling fins to prevent overheating. Total Méga 20W-50 oil is recommended due to its high-temperature stability in air-cooled applications. Overloading or sustained high-speed operation without adequate airflow can lead to cylinder head warping, especially on pre-1976 units. The gear-driven timing system requires no maintenance, enhancing long-term reliability. Regular fuel filter changes are essential to prevent injector pump wear. This engine is sensitive to poor fuel quality, and operation on non-EN 590 diesel increases risk of injector coking and pump failure.
Oil Specs: Requires Total Méga 20W-50 (Citroen SB 72/065). Compatible with API CD/CC specifications.
Emissions: Pre-Euro certification applies to all models (1972–1980) (VCA Type Approval #VCA/EMS/1122).
Power Ratings: Measured under ISO 1585 standards. Output consistent across fuel grades meeting EN 590.
Citroen Technical Information System (TIS): Docs CT-XY7-ARCH, CT-XY7-FUEL, CT-XY7-COOL
VCA Type Approval Database (VCA/EMS/1122)
Citroen Engineering Specification XY7-ENG-01
ISO 1585 Road Vehicles — Engine Test Code — Net Power
The Citroen 150D (XY7) was used across Citroen's Ami/Dyane platforms with transverse mounting and designed for lightweight commercial adaptation. This engine received platform-specific tuning—reinforced crankshaft in the Ami 8 Fourgonnette and modified carburettor linkage in the Dyane 6 Décalée—and from 1976 updated head gasket material improved thermal durability, creating service part differences. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the top surface of the cylinder block near the distributor (Citroen TIS CT-XY7-ID). The 7th digit of the chassis number indicates engine type ('D' for diesel). Pre-1976 models have a ribbed aluminium head; post-1976 units use a smoother casting with improved cooling ribs. Critical differentiation from petrol variants: 150D (XY7) has no radiator and uses a Bosch M-System mechanical injection pump. Service parts require model year verification—head gaskets before 1976 are not interchangeable with later models due to material revisions (Citroen SB 73/089).
The 150D (XY7)'s primary reliability risk is cylinder head warping in early production models, with elevated incidence in vehicles used for commercial hauling or in hot climates. Internal Citroen field reports from 1977 indicated head distortion in approximately 10% of pre-1976 engines exceeding 80,000 km, while UK DVSA MOT data shows cooling system integrity as a leading cause of failure in air-cooled derivatives. Inadequate airflow and delayed maintenance increase thermal stress, making duct inspection and service adherence critical.
Analysis derived from Citroen technical bulletins (1972-1980) and UK DVSA failure statistics (1975-1990). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about CITROEN 150D-XY7.
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Regulation (EC) No 715/2007
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