Copyright by Goodheart-Willcox Co., Inc.
506 Auto Engine Repair
Rear upper cover
Front upper cover
Rubber seal Engine mount
bracket
Timing belt
Back cover
Key
Rubber seal
Timing belt drive pulley
Crankshaft position sensor
Idler pulley
Idler pulley bolt
Auto-tensioner
Crankshaft pulley
Pulley bolt
Lower cover
Figure 23-11. This is an exploded view of the front end on an OHC engine that has a timing belt. (Honda)
Feel and listen
for dry bearings
Spin belt
tensioner
Figure 23-12. Spin the timing belt tensioner by hand to check
for dry or rough bearings. Replace the tensioner if it does not
spin freely. (Mazda)
Cover backing
plate
Camshaft
dowel
Sprocket slot or hole is
aligned with the dowel
Camshaft
sprocket bolt
Camshaft sprocket
Figure 23-13. A small dowel pin is often used to position the
timing belt sprocket.
Caution: The lubrication in the belt tensioner
bearings can dry out and the bearing can
lock up. This can cause timing belt failure
and severe engine damage. Never install a worn
tensioner that has dry bearings.
Installing Timing Belt Sprockets
The camshaft sprocket usually fits over a small steel
dowel in the camshaft, as in Figure 23-13. The sprocket is
secured by one or more bolts.
1. Install the camshaft sprocket.
2. Torque the camshaft sprocket fastener(s) to specifica-
tions. Usually, a flat is provided on the camshaft so
you can hold the camshaft while tightening the bolt(s),
Figure 23-14. Make sure you do not damage a cam-
shaft lobe or the sprocket teeth when trying to hold the
camshaft! Grasp an unmachined surface if needed.