Timing belts are typically only used on overhead camshaft engines. Timing belts are used to synchronize the crankshaft with the camshaft, similar to a timing chain on an overhead valve (pushrod) engine. Unlike a timing belt, a timing chain will normally last the life of the engine without needing service or replacement. Timing belts use raised teeth to mesh with sprockets to operate the valvetrain of an overhead camshaft engine.
Whenever a vehicle with an unknown service history comes into your repair facility or is recently purchased, here are some points that should be asked to help prevent costly engine damage:
Engines, chain-or belt-driven, can be classified as either free-running or interference, depending on what would happen if the piston-to-valve timing were disrupted. A free-running engine is designed with enough clearance between the pistons and valves to allow the crankshaft to rotate (pistons still moving) while the camshaft stays in one position (several valves fully open). If this condition occurs normally, no internal engine damage will result. In an interference engine, there is not enough clearance between the pistons and valves to allow the crankshaft to turn without the camshaft being in time.
An interference engine can suffer extensive internal damage if a timing belt fails. The piston design does not allow clearance for the valve to be fully open and the piston to be at the top of its stroke. If the belt fails, the piston will collide with the valve and will bend or break the valve, damage the piston, and/or bend a connecting rod. When this type of failure occurs, the engine will need to be replaced or disassembled for further internal inspection; either choice costing many times that of replacing the timing belt.
The average replacement interval for a timing belt is approximately 60,000 miles (96,000km). If, however, the timing belt is inspected earlier or more frequently than suggested, and shows signs of wear or defects, the belt should be replaced at that time.
Inspect both sides of the timing belt. Replace the belt with a new one if any of the following conditions exist:
If none of these conditions exist, the belt does not need replacement unless it is at the recommended interval. The belt MUST be replaced at the recommended interval.
Removal & Installation
1.5L (Z5d) And 1.8L (Bpd) Engines
- Remove all necessary components for access to the timing belt covers, then remove the covers.
- Turn the crankshaft until the timing mark on the crankshaft sprocket aligns with the timing mark on the oil pump and the camshaft sprocket timing marks align on the camshaft sprockets.
- Remove the crankshaft pulley lockbolt and pulley boss.
- Lower the vehicle. Insert a camshaft sprocket holding tool between the camshaft sprockets.
- Loosen the tensioner pulley lockbolt. Pull the tensioner pulley away from the center of the engine to reduce the tension on the timing belt.
- If the timing belt is to be reused, mark the direction of rotation on the timing belt. Remove the timing belt.
To remove the tensioner, unhook the tensioner spring, and remove the pulley lockbolt and tensioner.
- Install the crankshaft sprocket bolt. Install the flywheel locking tool, if equipped with automatic transaxle, or place the shift lever in 4th gear and apply the parking brake, if equipped with manual transaxle. Tighten the bolt to 108-116 ft. lbs. (147-157 Nm).
- Be sure the timing marks on the camshaft and crankshaft sprockets are still aligned.
- If removed, position the tensioner with the spring fully extended, and install the lockbolt tightening the mounting bolt to 28-38 ft. lbs. (38-51 Nm).
- Install the timing belt. If reusing the original timing belt, be sure it is installed in the same direction of rotation.
- Rotate the crankshaft clockwise 1 5 / 6 turns and align the timing marks. Be sure all marks are still correctly aligned.
- Loosen the tensioner lockbolt to apply tension to the timing belt. Tighten the tensioner lockbolt to 28-38 ft. lbs. (38-51 Nm). Remove the holding tool from between the camshaft sprockets.
- Rotate the crankshaft clockwise 2 1 / 6 turns and be sure all marks are still correctly aligned.
- Raise and safely support the vehicle. Install the crankshaft pulley lockbolt and boss. Tighten the bolt to 116-122 ft. lbs. (157-166 Nm).
- Install the timing belt covers.
- Before servicing the vehicle, refer to the Precautions section.
- Drain the cooling system.
Remove or disconnect the following:
Negative battery cable
Support the engine with a suitable support device and remove the number 3 engine mount.
Timing belt cover
- Install the pulley boss on the crankshaft and tighten the bolt.
Turn the crankshaft until the timing marks on the crankshaft and camshaft sprockets are aligned. Face the camshaft pulley marks
straight up, then align the timing marks with the horizontal surface on the cylinder head. The pin on the pulley boss must face upward. Hold the crankshaft pulley boss with a suitable tool and remove the pulley lockbolt, being careful not to rotate the crankshaft. Remove the crankshaft pulley boss.
NOTEProtect the tensioner with a shop towel before prying on it. Do not rotate the crankshaft after the timing belt has been removed.
- Mark the direction of rotation on the timing belt. Loosen the tensioner lockbolt and pry the tensioner outward. Tighten the lockbolt with the tensioner spring fully extended. Remove the timing belt.
- Remove the tensioner and spring. If necessary, remove the idler pulley.
Inspect the belt for wear, peeling, cracking, hardening or signs of oil contamination. Inspect the tensioner for free and smooth rotation. Check the tensioner spring free length; it should not exceed 2.43 inch (68mm). Inspect the sprocket teeth for wear or damage. Replace parts, as necessary.
- Install the crankshaft sprocket bolt and temporarily tighten.
- Install the tensioner and tensioner spring. Install the spring with the damper rubber closing face on the right side. Temporarily tighten the tensioner lockbolt with the tensioner spring fully extended.
- Face the I and E marks of the camshaft pulley marks straight up, then align the timing marks with the horizontal surface on the cylinder head. Refer to the illustration for timing mark alignment.
Install the timing belt so there is no looseness, refer to the illustration for location as follows:
- Make sure no pressure other than the tensioner spring is applied to the belt. If reusing the old belt, be sure it is installed in the same direction of rotation.
- Temporarily install the pulley boss and lockbolt.
Turn the crankshaft 1
turns clockwise and align the crankshaft sprocket timing mark with the tension set mark for proper belt tension adjustment. Remove the lockbolt and pulley boss.
CAUTIONDo not let the tensioner move with the tensioner lock bolt as it is turned.
Remove the pulley bolt and boss. and verify the timing belt pulley mark is still aligned with the tensioner set mark.
- Tighten the tensioner lock bolt.
- Temporarily install the pulley boss and lockbolt.
Turn the crankshaft 2
turns clockwise and face the pin on the pulley boss upright. Be sure the camshaft sprocket timing marks are aligned. If they are not, repeat the alignment steps.
NOTEThe timing marks are aligned normally if the camshaft pulley marks I and E are facing straight up, the timing marks are aligned to the horizontal surface on the cylinder head.
- Apply approximately 22 lbs. (10 kg) pressure to the timing belt at a point midway between the camshaft sprockets. The belt should deflect 0.24-0.29 inch (6-7.5mm). If the deflection is not correct, repeat the alignment and tensioning procedure.
- Install the pulley boss and lockbolt. Tighten the bolt to 116-122 ft. lbs. (157-166 Nm).
- Install the timing belt covers and tighten the bolts to 95 inch lbs. (11 Nm).
- Install the number 3 mount and remove the engine support device.
Install or connect the following:
Rocker arm cover with a new gasket