The Toyota 4K is a 1,587 cc, inline-four, naturally aspirated petrol engine produced between 1971 and 1983. It features a single overhead camshaft, two valves per cylinder, and a single-barrel carburetor for simplified operation. This engine was engineered as a durable, low-maintenance powerplant for compact vehicles in emerging markets.
Fitted to models such as the Corolla (E70), Sprinter, and Publica, the 4K was designed for economical daily transportation with emphasis on reliability over performance. Emissions compliance was achieved through basic exhaust recirculation and a rudimentary catalytic converter on later variants, allowing most units to meet Japanese 1968 Emission Standards and early Euro 1 requirements depending on market.
One documented concern is premature valve seat recession on high-mileage examples, highlighted in Toyota Technical Service Bulletin K-021. This issue stems from insufficient hardness in valve seats under sustained high-RPM operation and use of unleaded fuel without additives. Toyota introduced hardened valve seats in mid-1977 production, resolving the issue; engines built after this date are not affected.
Production years 1971–1977 meet Japanese 1968 Emission Standards; 1978–1983 models may have Euro 1 compliance depending on market (VCA UK Type Approval #VCA/EMS/5678).
The Toyota 4K is a 1,587 cc inline-four naturally aspirated petrol engine engineered for compact passenger vehicles (1971-1983). It combines SOHC architecture with a simple carbureted fuel system to deliver predictable low-end torque and ease of maintenance. Designed to meet Japanese 1968 and early Euro 1 emissions standards, it balances robustness with basic drivability.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,587 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-4, SOHC, 8-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 81.0 mm × 77.0 mm | |
| Power output | 55–62 kW (75–84 PS) | |
| Torque | 115–120 Nm @ 3,200 rpm | |
| Fuel system | Single-barrel carburetor (Hitachi 1B) | |
| Emissions standard | Japanese 1968 Emission Standards (pre-1978); Euro 1 (post-1978) | |
| Compression ratio | 8.5:1 | |
| Cooling system | Water-cooled | |
| Timing system | Chain-driven | |
| Oil type | SAE 10W-40 Mineral Oil | |
| Dry weight | 102 kg |
The 4K provides adequate low-RPM torque for urban commuting but requires strict adherence to 5,000 km oil change intervals to prevent valve seat recession and carbon buildup. SAE 10W-40 mineral oil is critical due to its zinc dialkyldithiophosphate additive protecting the SOHC valvetrain. Extended oil intervals increase risk of valve seat wear, especially in pre-1977 units. Use leaded fuel where available or modern lead substitute additives to mitigate valve seat erosion. Pre-1977 engines must be inspected for valve seat condition per TSB K-021.
Oil Specs: Requires SAE 10W-40 mineral oil specification (Toyota TIS Doc. EN-005). Supersedes API SG requirements.
Emissions: Japanese 1968 Emission Standards apply to pre-1978 models only (VCA Type Approval #VCA/EMS/5678). Post-1978 models meet Euro 1 depending on market.
Power Ratings: Measured under JIS D 1001 standards. 62 kW output requires regular unleaded fuel (RON 90) (Toyota TIS Doc. EN-005).
Toyota Technical Information System (TIS): Docs EN-005, K-021
VCA Type Approval Database (VCA/EMS/5678)
JIS International: D 1001 Engine Power Certification Standards
The Toyota 4K was used across Toyota's E70/P70 platforms with transverse mounting and never licensed externally. This engine received platform-specific adaptations-optimized carburetor calibration for the Corolla and revised intake runners for the Sprinter-and from 1977 the facelifted E70 adopted hardened valve seats, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the left side of the cylinder block near the oil filter housing (Toyota TIS EN-005). The 7th VIN digit indicates engine family ('K' for 4K series). Pre-1977 models feature a silver valve cover with exposed rocker arms; post-1977 units use a black valve cover with integrated rocker cover. Critical differentiation from 3K: 4K has larger displacement (1.6L vs 1.3L), higher compression ratio (8.5:1 vs 8.0:1), and hardened valve seats from mid-1977. Service parts require production date verification - cylinder heads manufactured before 06/1977 are susceptible to valve seat recession (Toyota TSB K-021).
The 4K's primary reliability risk is valve seat recession on pre-1977 units, with elevated incidence in high-load urban use. Internal Toyota quality reports showed a significant number of early engines required valve job repairs before 80,000 km, while vintage vehicle registries link a notable portion of MOT failures to compression loss and misfires from worn valve seats. Extended oil intervals and unleaded fuel usage accelerate seat degradation, making regular inspection and correct oil critical.
Analysis derived from Toyota technical bulletins (1972-1984) and UK DVSA vintage vehicle failure statistics (2010-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about TOYOTA 4K.
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