Thread: 300tdi vacuum pump fix

I didnt remove the core plug as it wasnt leaking, i think your up for a newy now.

Looks like one of your poppet valves has broken up. The spring is normally enclosed in the poppet housing, and sits behind the poppet diaphragm, pushing the diaphragm closed when required in the operation cycle. The poppet valve cannot be opened up to access the spring and diaphragm without basically destroying the poppet valve housing.

I would say this poppet valve, when it was in one piece, sat in the empty hole. From memory, this poppet valve is the only one of the four that cannot be removed, inspected and reinstalled. The metal of the casing is actually used to hold the valve, the metal edging of the hole being deformed over the valve (protected from the deforming force by the washer?). It is possible the deformed edging of the hole has broken away and released the valve, which has then been smashed to pieces.

I think the other 3 poppets are held in place by star washers, which can be carefully pried out and reused.