Timing Belt Inspection Unit Repair

1. Inspect the camshaft drive and the camshaft components for signs of excessive wear or unusual conditions. Note any evidence of oil or other fluid intrusion.
2. Verify if the camshaft timing belt length is within specification by using the following method.



3. Measure the timing belt tensioner actuator from the centerline of the actuator to the end of the rubber boot.

•	If the measurement reads from 80.5 -94 mm (3.2-3.7 in) for a used timing belt, the belt is within an acceptable range.

•	If the measurement reads over 94 mm (3.7 in) for a used timing belt, replace the belt.

4. Inspect the timing belt teeth and the back side of the belt for cracks, tears or other damage.

•	Replace the timing belt if any of these conditions are found.

•	Replace the timing belt and inspect the pulley alignment if the overall belt width is below 30 mm (1.18 in).

1. The following conditions may cause a broken or cracked tooth or tooth root:

•	Camshaft jamming

•	A damaged camshaft or crankshaft oil seal

•	A coolant leak

•	Old age (70,000 miles or more depending on the usage)

•	The tensioner not functioning




2. The following conditions may cause the back surface to crack or become scratched:

•	The tensioner jamming

•	An overheated engine

•	Interference with the belt cover





Important: Measure the width at the root of the tooth.

3. Side surface wear is defined by the following conditions:

•	The belt corners are worn and round

•	The wicks are frayed and coming out at the edge

4. The following conditions may cause the side surface to become worn (the belt width is below 30 mm (1.20 in)):

•	Improper installation of the belt (prying)

•	Overload, bending or misalignment of the cam drive components

•	The tensioner jamming

•	Heavy thrust loading against guide flanges

•	Damaged guide




5. Worn teeth are defined by the following conditions:

•	The canvas on the tooth face is worn down

•	The canvas on the tooth is fluffy

•	The rubber layer is worn down and faded white

•	The belt is worn down and invisible

6. The following may cause the teeth to wear:

•	Poor belt cover sealing

•	The camshaft not functioning properly

•	Excessive belt tension or tensioner jamming

•	Rough, scored, or nicked sprockets




7. The following conditions may lead to a clean break across the fibers:

•	A kinked or bent belt before or during assembly (bend smaller than a 30.0 mm (1.18 in) radius

•	Foreign material under the belt

8. The following conditions may cause oil/coolant or water to stick to the belt, and they may lead to swollen rubber:

•	Poor oil sealing of each oil seal

•	Coolant leakage at the coolant pump

•	Poor belt cover sealing