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Home >> Mercedes Benz >> 2004 >> G500 >> Repair and Diagnosis >> Brakes >> Mechanical - Hydraulic >> Brakes - Pneumatic System -- G-Class (463) >> Basic Knowledge >> Brake system vacuum pump, location/task/design/function - GF43.10-P-3101GG

Brake system vacuum pump, location/task/design/function - GF43.10-P-3101GG

MODEL 460, 461.217 /219 /223 /227 /229 /238 /239 /249 /266 /267 /302 /321 /322 /323 /326 /327 /328 /329 /331 /332 /335 /336 /337 /338 /341 /342 /345 /365 /366 /367 /368 /401 /402 /403 /404 /405 /450 /451 /452 /454 /455 /456 /458 /459, 463 

Task 

Produce vacuum for the brake unit

Design 

Piston pump (installed on engines 602, 603)

  1. 2 Reed valve (suction side)
  2. 4 Piston
  3. 5 Reed valve (pressure side)
  4. 6 Separation valve
  5. 7 Gasket
  6. 8 Pump housing
  7. 9 Pump cover
  8. 12 Oscillating lever
  9. 14 Outer compression spring
  10. 15 Bottom compression spring
  11. 16 Roller
  12. 17 Piston rod
  13. 21 Inner compression spring
  14. 23 Top spring plate
  15. 28 Piston ring
  16. 30 Radial seal ring
  17. 31 Oil retaining valve
  18. 32 Restrictor

SB = Suction side, brake

SK = Suction side, idle speed increase

Fig 1: Identifying Design Of Brake System Vacuum Pump
G07710891Courtesy of MERCEDES-BENZ USA

IMPORTANT Special maintenance is not required

Function 

Double-acting piston vacuum pump. It is flanged-mounted on the timing case cover.

It is driven by the cam of the injection timer and lubricated by oil spray from the engine.

The pump cover is made from sheet steel and caulked to the pump housing. The vacuum pump can therefore no longer be repaired. The vacuum pump works in both directions, i.e. it has two suction circuits, which however are connected to each other via a separation valve.

One circuit supplies the brake unit and the other the auxiliaries, such as, idle speed increase. An oil retaining valve is installed in both connections. A 0.8 mm dia. fixed orifice is located in the connection for the auxiliaries so that the brake unit circuit and idle speed increase are supplied as high priority.