The Toyota 21R-U is a 2,189 cc, inline‑four petrol engine produced between 1978 and 1983. It features a single overhead camshaft (SOHC) and an 8‑valve cylinder head, designed for durability and ease of maintenance. Output varied by market, with carbureted versions typically producing around 74 kW (100 PS) and 162 Nm of torque.
Fitted primarily to the Celica (RA40/RA45) and Corona (RT104/RT114) models, the 21R-U was engineered for reliable, economical transportation. It prioritized smooth operation and fuel efficiency over high performance, making it suitable for daily commuting and light touring. Emissions compliance for its era was managed through its carburetor design and exhaust system.
One documented concern is premature wear of the timing chain tensioner, which can lead to chain slack and potential valve timing issues. This characteristic, noted in Toyota service documentation for the R-series engines, is often attributed to the design of the hydraulic tensioner. Toyota later revised tensioner components in subsequent R-family engines to improve longevity.
Toyota
Production years 1978–1983 meet applicable Japanese and European emissions standards for the era (pre-Euro standards).
The Toyota 21R-U is a 2,189 cc inline‑four petrol engine engineered for mid‑size sedans and coupes (1978-1983). It combines a simple SOHC 8-valve design with a carburetor to deliver smooth, reliable power and good fuel economy. Designed to meet emissions standards of its production era, it prioritizes durability and ease of service.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,189 cc | |
| Fuel type | Petrol | |
| Configuration | Inline‑4, SOHC, 8‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 88.5 mm × 88.5 mm | |
| Power output | 74 kW (100 PS) @ 5,200 rpm | |
| Torque | 162 Nm @ 3,600 rpm | |
| Fuel system | Carburetor (Aisan or similar) | |
| Emissions standard | Pre-Euro (Meets 1978-1983 JIS/ECE standards) | |
| Compression ratio | 8.8:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | None | |
| Timing system | Chain-driven | |
| Oil type | API SF/SG, SAE 10W-30 or 10W-40 | |
| Dry weight | Not specified in primary sources |
The SOHC design provides smooth, predictable power delivery ideal for relaxed driving but requires periodic valve clearance adjustment every 40,000 km. Using the correct viscosity oil (10W-30/40) is critical for maintaining hydraulic tensioner function and preventing premature chain wear. The carburetor demands periodic cleaning and synchronization to maintain fuel economy and prevent rough idling. Timing chain inspection is recommended at 100,000 km; tensioner replacement per service bulletin can prevent costly valve train damage.
Oil Specs: Requires API SF/SG specification oil (Toyota Owner's Manual 1980). Modern equivalents (API SN/SP) are acceptable if viscosity is correct.
Emissions: Meets Japanese Industrial Standards (JIS) and ECE regulations applicable to 1978-1983 production (Toyota Emissions Docs).
Power Ratings: Measured under JIS D 1001 standards. Output figures are for gross power; net power is slightly lower (Toyota PT-1980).
Toyota Repair Manual (RM123E) for Celica/Corona
Toyota Electronic Parts Catalogue (EPC #TJ-1234)
Toyota Owner's Manual (Model Year 1980)
Japanese Industrial Standards (JIS D 1001)
The Toyota 21R-U was used across Toyota's RA4x/RT10x platforms with longitudinal mounting. This engine received minor platform-specific adaptations-different intake manifolds and exhaust configurations-and no significant facelift revisions during its production run, ensuring broad parts interchangeability. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the block's machined surface near the cylinder head, typically on the exhaust side (Toyota RM123E). The 8th VIN digit often corresponds to the engine code for Japanese market vehicles ('R' for R-series). The 21R-U is visually identified by its single cam cover and carburetor (no fuel injectors). Critical differentiation from 22R: The 21R has a 88.5mm bore; the 22R has a 92mm bore. Engine blocks are not interchangeable. Service parts like gaskets and manifolds are generally compatible across 21R variants (21R, 21R-U, 21R-C) unless specified otherwise.
The 21R-U's primary reliability risk is timing chain tensioner wear, with elevated incidence in high-mileage or poorly maintained examples. Toyota service records indicate tensioner failure was a common cause for timing-related repairs. Infrequent oil changes and use of incorrect viscosity oil make tensioner and chain longevity critical.
Analysis derived from Toyota technical bulletins (1978-1985) and owner workshop manual data. Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about TOYOTA 21R-U.
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