GM Service Manual Online
For 1990-2009 cars only

No 4th or Slipping 4th

Checks

Causes

Checkball #2, 4, 8 or 12

Valve body checkball in wrong location or an additional checkball is installed. Refer to Control Valve Body Installation.

Orificed Cup Plug (240)

Not fully pressed into pump cover. Refer to Oil Pump Stator Shaft Bushing Replacement.