Buick Century 1982-1996 2.5L Engine Specifications

The 2.5L engine in the 1982-1996 Buick Century is an inline-4 cylinder engine with a displacement of 151 cubic inches. It features a cast iron block and aluminum cylinder head, with a compression ratio of 8.7:1. The engine produces approximately 90 horsepower at 4,400 RPM and 130 lb-ft of torque at 2,800 RPM. It uses a carburetor-based fuel system up to 1986 and a throttle-body fuel injection system from 1987 onwards. The engine is compatible with various Buick Century models during this production range.

Regular maintenance for the 2.5L engine includes oil changes every 5,000 miles using 5W-30 synthetic oil, replacement of the air filter every 15,000 miles, and spark plug replacement every 30,000 miles. The coolant should be flushed and replaced every 50,000 miles, and the serpentine belt should be inspected and replaced as needed. Additionally, the fuel filter should be replaced every 15,000 miles, and the PCV valve should be checked annually. Always use OEM or equivalent parts for optimal performance.

To install or replace the 2.5L engine, start by disconnecting the battery and draining the coolant and oil. Remove the engine mounts, transmission crossmember, and any connected components like the radiator and intake manifold. Carefully lift the engine out using a hoist and place it on an engine stand. Install the new engine by reversing the process, ensuring all connections are secure. Reconnect the battery, refill fluids, and perform a test drive to check for leaks or issues. Always follow proper safety procedures and consult a repair manual for detailed instructions.

Common issues with the 2.5L engine include low power, rough idling, and coolant leaks. Check the oxygen sensor for proper function, as a faulty sensor can cause poor fuel efficiency and reduced power. For rough idling, inspect the spark plugs and ignition wires for wear. Coolant leaks can often be traced to the intake manifold gasket or water pump. Use a scan tool to check for trouble codes and refer to a repair manual for specific diagnostic procedures. Always address issues promptly to prevent further damage.

To optimize performance, ensure regular tune-ups, including spark plug and fuel injector cleaning. Use high-quality fuel and consider upgrading to a high-performance air filter. Check and adjust the ignition timing as specified in the service manual. For additional power, consider aftermarket modifications such as a performance camshaft or headers, but ensure any modifications comply with local emissions regulations. Always follow proper installation and tuning procedures to avoid engine damage.