Rick's Free Auto Repair Advice

Timing belt — what is it?

Timing belt definition

A timing belt is mounted at the front of the engine and covered timing beltby a timing belt cover. It is used to rotate the camshafts in time with the crankshaft. In some applications the timing belt may also drive balance shafts in time with the crankshaft and camshafts. In still other applications, the timing belt may be used to drive a water pump. Timing belts are tensioned with spring loaded or hydraulic tensioners.

If a timing belt breaks while you’re driving, your engine will stop immediately stop running. If the engine is an interference style the valves will hit the pistons if the belt breaks while running. That will bend the valves and most likely destroy the engine. That’s why timing belt replacement is so important.

subaru timing belt routing

Subaru timing belt routing

Timing belt replacement interval

Timing belts wear out with mileage and age. The timing belt change intervals vary by engine and year, but is somewhere between 60,000 miles and 105,000 miles.

Timing belt replacement cost

Timing belt replacement can be as low as $400 for an older Subaru boxer engine or as high as $1,200 for a European engine. The cost of the belt is pretty much the same; it’s the labor that makes up the difference.

Replace water pump with timing belt?

Many shops recommend replacing the water pump with the

water pump driven by timing belt

Subaru water pump is driven by the backside of the timing belt.

timing belt along with camshaft seals. The thinking behind the recommendation is that in many applications the timing belt drives the water pump and the belt must be removed to replace the water pump and camshaft seals if they ever leak. So why not replace them now while the labor to remove the belt is already paid for?

That approach makes some sense if there’s a lot of labor involved to replace the belt and the change interval is close to 100K miles. If you change the timing belt at 100K miles but not the water pump or camshaft seals, chances are high that the water pump or seals will leak or fail before you reach the next belt change at 200K miles.

©, 2022 Rick Muscoplat

Posted on by Rick Muscoplat


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