There is no magnet in the monovalve. There is a solenoid for valve actuation. Does not sound like the monovalve is your problem since power is needed to shut off flow.

Put your hand on the in/out hoses of the monovalve. If they are both hot, monovalve is not the problem.

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked