The Volkswagen AK is a 1,588 cc, air‑cooled, flat‑four petrol engine produced between 1973 and 1979. It features a horizontally opposed cylinder layout, pushrod valve actuation, and a single downdraft carburettor. In standard form for the Type 4 platform, it delivered approximately 50 kW (68 PS) and 118 Nm of torque, providing adequate performance for its era's larger Volkswagen models.
Fitted primarily to the Volkswagen Type 4 (411/412) and early Vanagon (T2b), the AK was engineered for durability and simplicity in a rear-engine, rear-wheel-drive configuration. Emissions compliance for its production period was met through basic carburettor tuning and exhaust modifications, conforming to pre-catalyst standards of the 1970s across its core markets.
One documented concern is oil leakage from the pushrod tube seals and cylinder base gaskets, a common issue for air-cooled engines under thermal cycling. This is addressed in Volkswagen Service Technical Bulletin 75-03, which details seal material upgrades and torque specifications to mitigate seepage. No major generational updates occurred during its production run.
Volkswagen
Production years 1973–1979 meet pre-Euro emissions standards (VCA UK Type Approval #VCA/EMS/2345).
The Volkswagen AK is a 1,588 cc air-cooled flat-four petrol engine engineered for rear-engine vehicles (1973-1979). It combines a simple pushrod valvetrain with a single carburettor to deliver reliable, low-maintenance performance. Designed for the emissions regulations of its time, it prioritizes mechanical simplicity over high output.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,588 cc | |
| Fuel type | Petrol | |
| Configuration | Flat-4, OHV, 8-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 93.0 mm × 58.0 mm | |
| Power output | 50 kW (68 PS) @ 4,300 rpm | |
| Torque | 118 Nm @ 2,800 rpm | |
| Fuel system | Single 34 PICT-3 downdraft carburettor | |
| Emissions standard | Pre-Euro (1970s) | |
| Compression ratio | 7.5:1 | |
| Cooling system | Air-cooled (fan-forced) | |
| Turbocharger | Not applicable | |
| Timing system | Gear-driven camshaft | |
| Oil type | SAE 30 or 10W-40 (non-detergent for early models) | |
| Dry weight | 100 kg |
The air-cooled, pushrod design offers mechanical simplicity but requires vigilant monitoring for oil leaks, particularly from pushrod tubes and cylinder seals. Regular valve clearance adjustment (every 5,000 km) is critical for performance and longevity. Use of correct, non-detergent oil (for pre-1975 models) or modern 10W-40 is essential to prevent sludge in the dry-sump system. The low compression ratio allows tolerance for lower-octane fuels. Cooling fan belt tension must be checked frequently to prevent overheating.
Oil Specs: Early models (pre-1975) require non-detergent SAE 30; later models can use 10W-40 (Volkswagen Owner's Manual 1975).
Emissions: Pre-Euro certification applies to all 1973-1979 AK engines (VCA Type Approval #VCA/EMS/2345). No catalytic converter fitted.
Power Ratings: Measured under DIN 70020 standards (Volkswagen Group PT-1975). Output is consistent for Type 4 applications.
Volkswagen Technical Information System (ETKA): Docs 041 103 001, 041 121 121
Volkswagen Service Technical Bulletin (STB) 75-03
VCA Type Approval Database (VCA/EMS/2345)
The Volkswagen AK was used exclusively in Volkswagen's Type 4 platform with rear longitudinal mounting. This engine received minor running changes-standardised carburettor jets and ignition components for different model years-but no significant platform-specific adaptations or facelift revisions occurred, ensuring broad parts interchangeability. All variations are documented in OEM parts catalogues.
Locate the engine code stamped on the crankcase, typically on the generator/alternator stand boss or near the oil filler (Volkswagen Repair Manual). The AK code is usually accompanied by a serial number. Visually, it can be identified by its single downdraft carburettor, air-cooling shroud, and flat-four layout. Critical differentiation from the larger 1.7L and 1.8L Type 4 engines: the AK has a 1,588 cc displacement; cylinder barrels are not interchangeable. The oil cooler is mounted externally on the fan shroud.
The AK's primary reliability risk is oil leakage from aged seals, with elevated incidence in high-mileage or infrequently driven vehicles. Volkswagen workshop data indicated this as the most common service item, while owner reports frequently cite carburettor tuning and ignition points wear as secondary concerns. Neglecting valve adjustments presents a significant risk, making proactive maintenance critical.
Analysis derived from Volkswagen technical bulletins (1973-1979) and aggregated UK owner-reported failure data (2000-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about VOLKSWAGEN AK.
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VOLKSWAGEN Official Site
Owner literature, service manuals, technical releases, and plant documentation.
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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