SI05.30-W-0001A | Service Information on basic adjustment of the valve bridges | 3.9.99 |
ENGINE 904 in MODEL 375, 673, 674, 676, 970, 972, 975, 976
ENGINE 541 in MODEL 950, 952, 953, 954
ENGINE 542 in MODEL 950, 952, 954
Modification notes
1 | Check for refaced valve seats | ||
Valve bridge basic adjustment: | |||
2 | Clamp valve bridge in the vise | ||
3 | Release jam nut and unscrew adjustment screw approx. 3 turns | ||
4 | Place valve bridge over the guide bolt | ||
5 | Press downward and hold | With BR 500 counter to the spring load. | |
The valve bridge must bear against the valve stem. The adjustment screws face the exhaust side. | |||
6 | Screw in adjustment screw by hand while pressing down the valve bridge until the adjustment screw gently bears against the valve stem | The valve bridge must not move upward while doing this. | |
7 | Clamp valve bridge in the vise | ||
8 | Counterhold adjustment screw | The special tool (retainer wrench for counterholding) published in the maintenance manual vol. 1, | |
9 | Tighten jam nut | approx. 25 Nm | |
10 | Install valve bridge on cylinder head |
The basic adjustment must not be carried out with the valve bridges installed and may only be carried out if the valve seats have been refaced.
In model series 500, pin-guided valve bridges without adjustment screws are installed.