The toothed belt tension is checked with a special measuring device Opel-KM-510. With a correctly tensioned strip, the instrument indications should be as follows.
| Toothed belt | ||
| new | used | |
| Engine: | ||
| – cold | 6.0 | 5,0 |
| – warm | 8.0 | 7.5 |
The tension measurement is performed on the unloaded section of the belt, centrally between the coolant pump and the camshaft pulley.
■ Remove the upper and lower toothed belt covers.
■ Tighten the belt, by turning the crankshaft in the direction of movement by about 180 °. Perform this operation with a wrench placed on the pulley bolt or by rolling the car with the 4/5 running.
■ Place the tensioned measuring device on the toothed belt, above the alternator. The tabs on the device must engage the tooth grooves on the belt. Release the tool and read the belt tension.
Adjustment of the toothed belt tension is made by turning the housing of the coolant pump, using a special Opel-KM-509-A key. During:
- turning it upwards increases the tension,
- turning downwards reduces the belt tension.
Before adjusting, loosen the pump mounting bolts, and after adjusting the tension, tighten only slightly at first. Retract the crankshaft, then make a full turn in the direction of movement. Check belt tension again and adjust if necessary. Repeat this for so long, there will be no difference between the results of the last and the last but one measurement.