Tech - Discolored Coolant in Cooling System and Contamination of Reservoir

Some customers may comment about discolored coolant (usually dark and rust colored in appearance) and a ring of contamination material around the inside of the coolant recovery reservoir.

This condition may be caused by excess seal pellet (stop leak) residue material from sealer pellets installed at the assembly plant. Sealer pellet installation has since been discontinued on the above vehicles.

Important: This condition is unique to the 3.8L engine and should not be confused with the condition described in Corporate Bulletin Number 99-06-02-012B (Rust in Coolant System).

This condition is almost always confined to the coolant recovery reservoir, so it is not necessary to change the coolant. Clean the coolant recovery reservoir and test the radiator cap for proper function. Keeping the cooling system full at all times and performing the following procedure should eliminate future recurrence.

1. Remove the coolant recovery reservoir. Refer to the Coolant Recovery Reservoir Replacement procedure in the Engine Cooling sub-section of the appropriate Service Manual.
2. Clean the inside of the coolant recovery reservoir using soap and water. Thoroughly rinse the reservoir with clean water and drain.
3. Install the coolant recovery reservoir. Refer to the Coolant Recovery Reservoir Replacement procedure in the Engine Cooling sub-section of the appropriate Service Manual.
4. Test the radiator cap. Refer to the Pressure Cap Testing procedure in the Engine Cooling sub-section of the appropriate Service Manual.
5. Refill the coolant recovery reservoir with a 50/50 mixture of DEX-COOL® and clean drinkable or distilled water to the FULL HOT mark. Fill to the FULL HOT mark to compensate for any air that may be in the cooling system.
6. Top off the radiator, if necessary.
7. Instruct the customer of the importance of maintaining the proper coolant level in the radiator and coolant recovery reservoir.

For vehicles repaired under warranty, use: