Nissan VQ25DE Engine Workshop Manual

This manual provides detailed instructions for disassembling, repairing, removing and installing the VQ25DE engine. Includes step-by-step procedures with illustrations describing the disassembly of the main engine components, diagnostics and repair of faults, as well as tips on the use of special tools. The manual is designed to ensure accuracy and safety when performing technical work, will help to avoid errors and extend the service life of the engine. Free Download

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Years of production: 1994 – present. The VQ25DE is a member of the Nissan VQ engine family, known for its reliability and performance.

Cars it was installed on:

• Nissan Teana (J31, J32)
• Nissan Cefiro (A32, A33)
• Nissan Maxima (A32, A33)
• Nissan Skyline (V35)
• Nissan Stagea (M35)
• Nissan Fuga (Y50)
• Infiniti G25
• Infiniti JX

Operating principle:

• Gasoline, 6-cylinder V-shaped engine with a displacement of 2.5 liters.
• 24-valve, DOHC (double overhead camshaft) with a variable valve timing system VVT (Variable Valve Timing).
• Fuel injection is carried out by means of a multi-point injector (MPI), providing efficient mixing of fuel with air.
• Timing: Uses a chain rather than a belt, which increases reliability and eliminates the need for regular replacement typical of belt-driven engines. However, over time, the chain may stretch and require replacement, especially at high mileage.

Average fuel consumption: Depends on the vehicle and operating conditions, but on average is about 9-11 liters per 100 km in a combined cycle.

Engine weight: About 170-180 kg, which is considered an acceptable weight for an engine of this volume and power.

Maximum power: Depending on the engine and vehicle modification, the maximum power is 180-210 hp at 6000 rpm.

Maximum torque: About 230-250 Nm at 4400-4800 rpm, which ensures good acceleration dynamics and smooth running.

Materials of manufacture:

• Cylinder block: Aluminum alloy, which ensures lightness and good heat exchange.
• Cylinder head: Also made of aluminum alloy with 24 valves.
• Pistons: Aluminum, to reduce weight and improve thermal conductivity.
• Timing chain: Steel, with high wear resistance and durability.

Fuel system type: Multi-point fuel injection (MPI), optimizing the combustion process and reducing emissions of harmful substances.

Compression ratio: Depends on the modification, but on average is 9.8: 1 - 10.3: 1, which allows the use of high-octane fuel (not lower than AI-95).

Features and benefits:

• VVT system: Variable valve timing ensures optimal engine operation in different modes, improving dynamics and efficiency.
• Aluminum block: Lightness and excellent cooling contribute to efficient operation and reduced load on the front axle of the car.
• Long service life: With proper maintenance, the engine can travel more than 300,000 km without problems.

• Strengths of the VQ25DE engine:

Reliability and durability: This engine is highly reliable due to its robust design and high-quality materials used in production. With proper maintenance, the engine can operate for a long time without serious problems.

Good dynamics: The VQ25DE has excellent power and torque characteristics, which ensures good acceleration dynamics and allows you to feel confident on the road.

Low fuel consumption: For a 2.5-liter engine, the VQ25DE is quite economical. The fuel injection control system allows you to optimize consumption, especially with a calm driving style.

Technological: The use of the VVT (Variable Valve Timing) system ensures smooth and efficient engine operation in different modes, improving productivity and efficiency.

Relatively simple maintenance: Despite the complexity of some components, the engine is quite easy to maintain. Regular work can be carried out in ordinary car repair shops without specialized equipment.

• VQ25DE engine weaknesses:

Sensitivity to oil quality: The engine is sensitive to the quality and condition of the engine oil. Using low-quality lubricants or untimely oil changes can lead to premature wear of parts.

Cooling system problems: Over time, problems with the cooling system may occur, such as antifreeze leaks or thermostat failure. Overheating the engine can cause serious damage.

Timing chain wear: At high mileage, the timing chain may wear out, which can lead to loss of power and the appearance of extraneous noise.

Repair difficulties: In case of serious breakdowns, engine repair can be difficult and expensive due to the tight layout and inaccessibility of some components.

• How to properly maintain the VQ25DE engine:

Regular oil changes: Use only high-quality oil recommended by the manufacturer and change it every 5,000-7,000 km. Timely oil changes prevent premature wear of parts and maintain optimal engine performance.

Checking the coolant level: Monitor the level and condition of the coolant. Change it in accordance with the maintenance schedule and check the cooling system for leaks.

Replacing filters: The air and fuel filters must be replaced at the specified intervals to prevent dirt and foreign particles from entering the engine, which contributes to its longevity.

Timing chain monitoring: Regularly listen to the engine. If extraneous noises appear, such as a ringing sound of the chain, diagnose and, if necessary, replace the timing chain and tensioner.

Diagnosing the injection system: Periodically diagnose the fuel injection system, clean the injectors and monitor the operation of the sensors. This will help maintain engine efficiency and reduce fuel consumption.

Use quality fuel: Fill up with high-quality fuel (not lower than AI-95) at trusted gas stations to avoid problems with the fuel system and extend the life of the engine.

Regular diagnostics: Perform a comprehensive engine diagnostics at least once a year or when malfunctions occur. This will allow you to promptly identify and eliminate possible problems.