GM Service Manual Online
For 1990-2009 cars only

High or Low Line Pressure

Checks

Cause

Oil Level

High or Low; correct as required

    • Reverse Boot Valve (363)
    • Pressure Regulator Valve (365)
    • Springs (360, 364)
    • TV Boost Valve (361)

Stuck

Oil Filter (33)

Clogged, broken, or loose

Oil Filter Seal (32)

Leaking

Cooler Lines

Clogged or restricted

Oil Pump (21)

Damaged, sticking, porous, or leaking

Oil Pump Drive Shaft (18)

Damaged

Pump Priming Spring (359)

Stuck, Damaged

    • Transmission Case (15)
    • Valve Body (21)
    • Case Cover (401)
    • Porosity, leaking circuits
    • Flatness of machined surfaces