Grand Cherokee 2WD V8-5.2L VIN Y (1998)
Vacuum Brake Booster Check Valve: Testing and Inspection
1. Disconnect vacuum hose from check valve.
2. Remove check valve and valve seal from booster.
3. Use a hand operated vacuum pump for test.
Vacuum Check Valve And Seal
4. Apply 15 - 20 inches vacuum at large end of check valve.
5. Vacuum should hold steady. If gauge on pump indicates vacuum loss, check valve is faulty and should be replaced.