Removal & Installation
The timing belt can be inspected by removing the upper front outer timing belt cover.
Working on any engine (especially overhead camshaft engines) requires much care be given to valve timing. It is good practice to set the engine up at TDC No. 1 cylinder firing position before beginning work. Verify that all timing marks on the crankshaft and camshaft sprockets are properly aligned before removing the timing belt and starting camshaft service. This serves as a point of reference for all work that follows. Valve timing is very important and engine damage will result if the work is incorrect.
- Disconnect the negative battery cable.
- Remove the accessory drive belts. Remove the engine mount insulator from the engine support bracket.
- Remove the engine support bracket. Remove the crankshaft pulleys and torsional damper. Remove the timing belt covers.
- Rotate the crankshaft until the sprocket timing marks are aligned. The crankshaft sprocket timing mark should align with the oil pump timing mark. The rear camshaft sprocket timing mark should align with the generator bracket timing mark and the front camshaft sprocket timing mark should align with the inner timing belt cover timing mark.
- If the belt is to be reused, mark the direction of rotation on the belt for installation reference.
- Loosen the timing belt tensioner bolt and remove the timing belt.
- If necessary, remove the timing belt tensioner.
- Remove the crankshaft sprocket flange shield and crankshaft sprocket.
Hold the camshaft sprocket using spanner tool MB990775, or equivalent, and remove the camshaft sprocket bolt and washer. Remove the camshaft sprocket.
- Install the camshaft sprocket on the camshaft with the retaining bolt and washer. Hold the camshaft sprocket using spanner tool MB990775, or equivalent, and tighten the bolt to 70 ft. lbs. (95 Nm).
- Install the crankshaft sprocket.
- If removed, install the timing belt tensioner and tensioner spring. Hook the spring upper end to the water pump pin and the lower end to the tensioner bracket with the hook out.
- Turn the timing belt tensioner counterclockwise full travel in the adjustment slot and tighten the bolt to temporarily hold it in this position.
- Rotate the crankshaft sprocket until its timing mark is aligned with the oil pump timing mark.
- Rotate the rear camshaft sprocket until its timing mark is aligned with the timing mark on the generator bracket.
- Rotate the front (radiator side) camshaft sprocket until its mark is aligned with the timing mark on the inner timing belt cover.
Install the timing belt on the crankshaft sprocket while keeping the belt tight on the tension side.
NOTEIf the original belt is being reused, be sure to install it in the same rotational direction.
Position the timing belt over the front camshaft sprocket (radiator side). Next, position the belt under the water pump pulley, then over the rear camshaft sprocket and finally over the tensioner.
WARNINGIf any binding is felt when adjusting the timing belt tension by turning the crankshaft, STOP turning the engine, because the pistons may be hitting the valves.
- Apply rotating force in the opposite direction to the front camshaft sprocket (radiator side) to create tension on the timing belt tension side. Check that all timing marks are aligned.
- Install the crankshaft sprocket flange.
- Loosen the tensioner bolt and allow the tensioner spring to tension the belt.
- Rotate the crankshaft 2 full turns in a clockwise direction. Turn the crankshaft smoothly and in a clockwise direction only.
- Align the timing marks. If all marks are aligned, tighten the tensioner bolt to 250 inch lbs. (28 Nm). Otherwise repeat the installation procedure.
- Install the timing belt covers. Install the engine support bracket. Tighten the support bracket mounting bolts to 35 ft. lbs. (47 Nm).
- Install the engine mount insulator, torsional damper and crankshaft pulleys. Tighten the crankshaft pulley bolt to 112 ft. lbs. (151 Nm).
- Install the accessory drive belts and adjust them to the proper tension.
- Reconnect the negative battery cable.
- Run the engine and check for proper operation. Road test the vehicle.