Disassembling and checking the oil pump (BMW 5 Series E12)

Disassembly

Remove plug 1, spring 2 and plunger 3 of the pressure reducing valve.

Remove cover 4 of the oil pump.

Wash and blow out the oil pump parts with compressed air.

Checking the technical condition of parts

Measure the free length of the pressure reducing valve spring, which should be 68 mm.

Check the clearances between the outer rotor and the oil pump housing and between the inner and outer rotors, as well as the recession of the outer rotor relative to the end of the oil pump housing.

If the clearance between the outer rotor and the pump housing is greater than the norm, replace the pump housing. If the clearance between the inner and outer rotors exceeds the limit, replace the rotors. If the sinking of the outer rotor exceeds the limit, replace the oil pump housing.



To remove the inner rotor, press off the oil pump drive flange using a universal two-lever puller. Do not press off the flange using a lever.



When pressing on the oil pump drive flange, it is necessary to maintain dimension "A" (see photo), equal to 32.7±0.1 mm (models "518", "520") or 44.3±0.1 mm (models "525", "528").



On models "525" and "528" there is a ventilation hole in the oil pump housing connecting the discharge cavity with the pressure reducing valve (it is prohibited to drill such a hole on pumps whose design does not provide for it). Clean this hole with copper wire and blow it out with compressed air.

(The original text of the article is available on the resource: «BMWman»)