Check Valve (Power Brake Unit)
NOTE:
Check valve is press-fit into vacuum hose. DO NOT remove check valve from vacuum hose. Replace check valve and vacuum hose as an assembly.
Remove vacuum hose and check valve assembly. Apply vacuum to end of hose closest to intake manifold. If vacuum holds, replace check valve and hose assembly. Apply vacuum to end of hose closest to power brake unit. If vacuum does not hold, replace check valve and hose assembly.