GM Service Manual Online
For 1990-2009 cars only

An engine will overheat under the following conditions:

    • The radiator core is dirty
    • The radiator core is obstructed
    • The radiator core is leaking

Clean the outside of the radiator with the following equipment:

    • A soft bristle brush and clean hot water
    • A mild detergent solution such as car wash or dishwashing liquid
    • A common city water hose. Do not use the hose nozzle as damage to the fins may result

Cleaning Procedure

  1. Clean the inside of the core tubes by pressure flushing with clean, hot water and a mild car wash or a dishwashing liquid.

  2. Object Number: 258834  Size: SH
  3. Warm the engine in order to test the radiator for restrictions.
  4. Turn off the engine and feel the radiator. The radiator should be hot along the top side and warm along the bottom side. You should feel an even temperature rise from top to bottom. Cold spots in the radiator indicate clogged sections.