1998 Mitsubishi Eclipse Balance Shaft Belt Tensioner Replacement Cost

The balance shaft belt tensioner, as the name implies, provides tension to the balance shaft belt to ensure total contact between the teeth on the belt and the teeth on the balance shaft and crankshaft timing gears. With the appropriate amount of tension from the belt tensioner, the belt and gears will remain aligned so the balance shaft remains properly timed to the engine.

As the balance shaft belt is installed this balance shaft belt tensioner pulley is tightened to manufacturer specifications, and that places the proper amount of tension on the belt. It is bolted through the center into the engine, and the smooth side of the balance shaft belt rests tightly against the pulley as it constantly rotates.

If the balance shaft belt tensioner fails, there will be a very audible chirping noise from the front of the engine. This is because the tensioner bearing is no longer smooth. If it is not changed immediately, the engine will being running roughly, and vibration will be evident throughout the vehicle. As a worst-case scenario, internal engine damage may occur due to slippage or breakage of the balance shaft belt. The check engine light will illuminate on the dashboard in the event of total failure or breakage of the balance shaft belt.

It is not recommended to drive a vehicle suspected of timing component damage, and the balance shaft belt and tensioner are responsible for the timing of the balance shaft to the engine. If the vehicle will run, operating the vehicle may result in damage or total failure to the engine.

balance shaft belt tensioner pulleys are replaced during a balance shaft belt replacement service, either as preventive maintenance, or due to suspected failure. This means the average balance shaft belt tensioner replacement occurs between 60,000 and 105,000 miles, depending on the manufacturer specified balance shaft belt service interval.

Diagnosis of a failed or failing tensioner requires removal of many components, and hands on inspection of the balance shaft belt tensioner. If the servicing technician finds the pulley is loose or damaged in any way, they will recommend immediate replacement of, at minimum, the balance shaft belt and balance shaft belt tensioner pulley.

At a minimum, replacement involves removal of the timing cover, balance shaft belt tensioner, balance shaft belt, and the balance shaft belt pulley. The balance shaft belt tensioner is typically attached by one bolt, but installation requires the proper amount of tension to be applied to the balance shaft belt and idler pulley retaining bolt. Once all components are replaced, the timing components can be installed onto the engine, and the engine will be tested for proper operation and balance shaft timing before additional components are replaced.

Since this service requires removal of the balance shaft belt and timing cover, it is recommended to replace the timing belt, water pump and possibly front seals at the same time, unless they have been recently serviced. This is much more cost effective than returning for the same service after a partial service interval has elapsed.

It may be necessary for the motor mounts to be removed from the vehicle, as well as engine cooling fans, the radiator, and all engine accessories. This may include components like the alternator, A/C compressor, mounting brackets, coolant or fuel lines, and any other component that interfere with access to the timing cover or front cover.

Since balance shaft belt tensioner replacement necessitates the removal of timing components, it is not recommended for the DIYer to attempt this task. A thorough knowledge of internal engine components, engine timing, accessory systems, and several specialty tools are required to properly perform this repair.