Strider,
40,000 km or 40,000 miles (= 64,000 km) ?
That would be almost once a year for me.
Anyway, extract from Pelican parts:
Replacing the rubber timing belt is one of the most important maintenance tasks for the six-cylinder E30 engine. As the engine ages and mileage climbs, an old, worn-out timing belt may break, causing catastrophic engine damage. A broken timing belt typically causes the valves to hit the tops of the pistons, bending the valves and/or destroying the pistons. A broken timing belt can indeed lead to the complete destruction of the engine.
To avoid this fate, replace the timing belt every 60,000 miles or every four years. If you live in a dry climate (like Arizona), or if you don’t drive your car often, then I recommend replacing the belt more often. In dry climates, belts can become brittle and worn much more quickly. If your car sits for long periods of time, the belts take on the bends and shapes of the pulleys while the car is parked. Both circumstances increase the likelihood of belt failure.
Jack the car up to gain easier access to the crankshaft pulley and lower radiator hoses; it will also be easier to remove the coolant. Be sure to place the transmission in neutral so you can turn the engine more easily. Also remove the spark plugs, as this will make it easier still to turn the engine—and to recognize any interference problems when you install the new timing belt.
Although it’s not necessary, it’s wise to inspect and/or replace the water pump and thermostat at this time (see Project 35). As a rule, replace the water pump every second time you replace the timing belt.
E30 cars manufactured in 1986 and later years should have a tensioner marked with “Z 127.” If your tensioner does not have this code, replace it with one that does. This tensioner design replaced an earlier, potentially faulty, design.
Follow the procedure documented in the photos for detailed instructions on removing the timing belt and camshaft sprocket. Reinstall the tensioner before you install the new belt. To reinstall the tensioner, compress the spring as far as you can, and then temporarily tighten the adjustable tensioner bolt (green arrow, Photo 12). When you install the new timing belt, place it on the engine, working counterclockwise, starting from the crankshaft sprocket. Slip the belt over the intermediate shaft sprocket, around the tensioner, and over the camshaft sprocket. Now, loosen both bolts on the tensioner to apply tension to the timing belt. Verify that the timing marks for TDC on the camshaft sprocket match up with the notch on the cylinder head (see Photo 10). With a socket on the crankshaft pulley, carefully rotate the engine clockwise through two complete revolutions (720 degrees). Verify that the timing mark on the camshaft pulley is in place again. Torque the upper and lower tensioner mounting bolts to 22 N-m (16 ft-lbs).
With the tensioner in place, reinstall the crankshaft pulley and lower timing belt cover. Recheck that the camshaft sprocket is aligned with the cylinder head when the vibration damper or toothed timing wheel O/Tmark is aligned with the lower timing belt cover. If not, remove the damper and lower timing belt cover and reposition the belt. Reinstall the front pulley, applying red Loctite to the six mounting bolts.
When you’re finished, reinstall the radiator and bleed the cooling system as described in Project 33."
60,000 miles = 96,000 km ... same recommendation with Proton cars.
Keh! keh ! Keh! Driven the company Iswara 5 years back with a noticeable engine vibration. Told the fleet manager and he says just ignore it ... which I did ... had to call him to pick me up at Seremban Highway in the middle of the night ... timing belt broken, ... rockers broken, valves bent ... etc...:smokin:
