The manufacturer of the 1998 through 1993 1.6 Isuzu Impulse recommends that the timing belt be replaced at 60,000-mile intervals. This decision was arrived at after studying the service history of this engine. The 1.6 engine has been identified as an interference engine in which a timing belt failure is most likely to result in major internal engine damage. During this procedure, do not attempt to turn the crankshaft with the timing belt removed.
Tools Used: ¼-drive sockets, ¼-inch drive ratchet, ½-inch drive air gun, ½-inch drive sockets, 6mm diameter 1-1/2-inch long bolts, Floor jack, Metric wrenches, Screwdriver
Change Timing Belt
Support the engine with the floor jack. Remove the right engine mount and the accessory drive belts. Remove the wiring harness cover from timing belt upper cover and remove the timing belt cover. Remove the torque strut and bracket from the cylinder block, as well as the torque strut nut and bolt from the center beam.
Remove the stud and stiffener from the transmission housing and the flywheel cover. Use the large screwdriver and lock the flywheel by inserting the screwdriver into the aperture through the dust cover to hold it while the crankshaft pulley bolt is removed. Remove the crankshaft pulley. Remove the timing belt lower cover.
Turn the crankshaft clockwise until the keyway on the crankshaft sprocket is straight up and the "V" notch on the back of it above the keyway is lined up with the corresponding "V" on the block. This will give top dead center on the Number One cylinder. Make sure the camshaft sprockets marks are lined up with each other, the "E" on the right sprocket is straight up and the "I" on the left sprocket is up as well. If not, turn the engine one more revolution, and they will line up.
Lock the camshaft sprockets using the 6mm bolts in the holes provided through the sprockets. Loosen the tensioner bolt ½ turn. Using an Allen wrench to turn the tensioner pulley clockwise enough to release the tension. Lightly tighten the bolt to hold the tensioner out of the way. Remove the timing belt.
Make sure all timing marks are lined up. Install the new timing belt starting on the right side at the crankshaft sprocket and work counterclockwise, keeping the belt tight between the crank and cam on the right side. Make sure the letters on the timing belt are readable from the front.
Remove the bolts locking the camshaft sprockets. Loosen the tensioner bolt and use an Allen wrench to turn the tensioner counterclockwise and apply firm tension to the belt. While keeping tension on the belt, tighten the tensioner bolt to 31 foot-pounds of torque.
Turn the engine clockwise two turns and recheck the timing marks. Install all components in reverse order of removal and torque the crankshaft pulley bolt to 123 foot-pounds of torque.
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