Below is a description for the M57 and M67 engines. The valve is located in the engine compartment near the left cylinder head.
1. Loosen the clamps (1) and quick-release coupling (2).
2. Remove the preheating valve (3).
3. Installation is carried out in the reverse order. If necessary, replace the coupling sealing ring (2). Replace the hose clamps (1).
4. After installation, pump the power supply system, not allowing the fuel pump to run without fuel (dry).
(Examine the original source using the link on the website «BMWMan»)