Surge Tank Filler Cap Check

em2 mm 20.01.001

    Warning: Do not remove or loosen the surge tank cap until the cooling system has completely cooled. Use extreme care when removing the cap. A sudden release of pressure from removing the cap prior to the system cooling can result in a surge of scalding coolant that could cause serious personal injury.

  1. Check the surge tank filler cap to see if it maintains pressure to within 10% of the pressure rating marked on the cap. If it does not, replace the cap. Make sure that the replacement cap is correctly rated for the cooling system of the vehicle. See Fig..

    1. Surge Tank Filler Cap

    2. Surge Tank

    Fig. 1, Surge Tank

  2. There is a valve in the filler cap that opens under vacuum. This prevents the collapse of hoses and other parts that are not internally supported when the system cools. Inspect the vacuum-relief valve to be sure it is not stuck.
  3. Make sure that the filler cap seals properly on the coolant filler neck seat, and that the O-ring is not cracked or deteriorated. Replace the cap if the O-ring shows deterioration or damage.
Note:
Parent topic: Cooling System
Document Number: 0000121552
Manual Publication Date: 2025-02-11
Topic Publication Date: 2024-06-04