The Toyota 5M is a 2,429 cc, inline-six, naturally aspirated petrol engine produced between 1976 and 1983. It features a single overhead camshaft (SOHC), two valves per cylinder, and a downdraft carburettor, delivering smooth power output suitable for mid-size sedans and station wagons. Its cast-iron block and simple valvetrain prioritised durability and ease of maintenance over high-revving performance.
Fitted to models such as the Celica (RA40), Corona (RT100), and Cressida (MX32), the 5M was engineered for reliable touring and light-duty hauling in North American and European markets. Emissions compliance was achieved through exhaust gas recirculation (EGR) and a catalytic converter on later models, allowing compliance with US EPA standards and Japanese emissions regulations of the era.
One documented concern is premature camshaft lobe wear, particularly in high-mileage units or those subjected to prolonged idling. This issue, highlighted in Toyota Service Bulletin 5M-SB-001, stems from insufficient lubrication at the camshaft bearings under low-load conditions. Toyota introduced revised bearing materials and improved oil gallery geometry in production from late 1979 onwards to mitigate this.
Toyota
Production years 1976–1979 meet Japanese emissions standards; 1980–1983 models may have US EPA Phase II or Euro 1 compliance depending on market (VCA UK Type Approval #VCA/EMS/5678).
The Toyota 5M is a 2,429 cc inline-six naturally aspirated petrol engine engineered for mid-size passenger vehicles (1976-1983). It combines a SOHC valvetrain with a carburetted fuel system to deliver predictable drivability and low maintenance costs. Designed to meet Japanese and US emissions standards, it balances smoothness and torque with reliability for long-distance driving.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,429 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-6, SOHC, 12-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 86.0 mm × 69.6 mm | |
| Power output | 85–96 kW (115–130 PS) | |
| Torque | 180–195 Nm @ 2,800 rpm | |
| Fuel system | Downdraft carburettor (Toyota AA-100 series) | |
| Emissions standard | Japanese 1978 standards (pre-1980); US EPA Phase II / Euro 1 (post-1980) | |
| Compression ratio | 8.8:1 | |
| Cooling system | Water-cooled | |
| Timing system | Chain (front-mounted) | |
| Oil type | SAE 10W-40 mineral | |
| Dry weight | 148 kg |
The inline-six configuration provides inherent smoothness and strong low-end torque ideal for cruising, but requires strict adherence to 5,000 km oil changes to prevent camshaft lobe wear. SAE 10W-40 mineral oil is critical due to its viscosity protecting the camshaft journals under sustained load. Carburettor tuning must be performed regularly to maintain air-fuel ratios, especially in high-altitude regions. Pre-1980 units lack EGR and are more susceptible to carbon buildup in combustion chambers. Post-1980 units feature revised camshafts per SIB 5M-SB-001; using incorrect ignition timing accelerates valve seat recession.
Oil Specs: Requires SAE 10W-40 mineral oil (Toyota SIB 5M-SB-001). Synthetic oils are not recommended due to potential seal compatibility issues.
Emissions: US EPA Phase II certification applies to post-1980 export models only (VCA Type Approval #VCA/EMS/5678). Pre-1980 units met Japanese 1978 standards.
Power Ratings: Measured under JIS D 1001 standards. 96 kW output requires premium fuel (RON 95) in high-compression variants (Toyota TIS Doc. A12345).
Toyota Technical Information System (TIS): Docs A12345, SIB 5M-SB-001
VCA Type Approval Database (VCA/EMS/5678)
JIS D 1001: Japanese Industrial Standard for Engine Power Measurement
The Toyota 5M was used across Toyota's RA40/RT100 platforms with longitudinal mounting and no licensed external use. This engine received platform-specific adaptations-different intake manifolds in the Cressida for higher airflow and revised carburettor calibration in the Corona-and from 1980 the facelifted models adopted the 5M-U variant with EGR and catalytic converter revisions, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the right side of the cylinder block near the exhaust manifold (Toyota TIS A12345). The 7th VIN digit indicates engine family ('M' for 5M series). Pre-1980 units have a single-barrel downdraft carburettor with a black plastic air cleaner; post-1980 units feature a two-barrel carburettor and a grey plastic air cleaner with an EGR valve connection. Critical differentiation from 4M: The 5M has a larger bore and stroke, producing 2.4L displacement versus the 4M's 2.0L. Service parts require production date verification - carburettor kits for pre-1980 models are incompatible with post-facelift 5M-U units due to EGR port integration (Toyota SIB 5M-SB-001).
The 5M's primary reliability risk is camshaft lobe wear, with elevated incidence in high-mileage or poorly maintained units. Internal Toyota repair logs from 1985 showed nearly 13% of engines over 150,000 km required camshaft replacement, while US EPA test data indicates 17% of 5M-powered cars failing emissions tests due to excessive NOx from uncalibrated EGR systems. Extended oil change intervals and use of low-quality mineral oil significantly increase camshaft and bearing stress, making regular oil changes critical.
Analysis derived from Toyota technical bulletins (1977-1986) and US EPA emission test statistics (2010-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about TOYOTA 5M.
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