GM Storm/Spectrum 1985-1993 Repair Guide

Cooling System


Check the cooling system at the interval specified in the Maintenance Intervals chart at the end of this section.

If necessary, hose clamps should be checked and soft or cracked hoses replaced. Damp spots or accumulations of rust or dye near hoses, the water pump or other areas indicate areas of possible leakage. Check the radiator pressure cap for a worn or cracked gasket. If the cap doesn't seal properly, fluid will be lost and the engine will overheat. A worn cap should be replaced with a new one. The radiator should be free of rust and the coolant should be free from oil. If oil is found in the coolant, the engine thermostat may not function correctly, therefore the system must be flushed and filled with fresh coolant.

Periodically clean any debris such as leaves, paper, insects, etc. from the radiator fins. Pick the large pieces off by hand. The smaller pieces can be washed away with water pressure from a hose.

Carefully straighten any bent radiator fins with a pair of needle nose pliers. Be careful - the fins are very soft. Don't wiggle the fins back and forth too much. Straighten them once and try not to move them again.


The recommended fluid is a 50/50 mixture of a ethylene glycol antifreeze and water for year round use. Make sure the solution is never less than 50 percent or more than 70 percent antifreeze. Use a good quality antifreeze with rust and other corrosion inhibitors, along with acid neutralizers.


See Figure 1

To check the coolant level, simply raise the hood and locate the see-through radiator surge tank. The tank has a MAX fill line to which the coolant level should always be raised, whether the engine is hot or cold. If necessary, remove the surge tank cap (NOT THE RADIATOR CAP, especially if the engine is warm) and add coolant to raise the level up to the MAX line.

Under certain conditions, air trapped in the system may adversely affect the surge tank and radiator's ability to obtain a proper level. If this is suspected, allow the engine too cool, then follow the fill portion of the Drain and Refill procedure later in this section.

Click image to see an enlarged view

Fig. Fig. 1: Whether the engine is hot or cold, the coolant level should always be even with the surge tank MAX fill line


  1. Make sure the engine is cool and the vehicle is parked on a level surface, then remove the radiator pressure cap.
  3. Position a large drain pan under the radiator drain plug, then open the radiator drain and allow the coolant to drain from the system.
  5. Close the radiator plug, then fill the system through the radiator using a suitable solution of water and a glycol antifreeze.
  7. Once the coolant level reaches the base of the radiator filler neck, leave the pressure cap OFF and start the engine.
  9. When the engine reaches normal operating temperature, the thermostat will open allowing coolant to flow into the engine and trapped air to escape from the coolant passages. At this point, more coolant will be necessary to bring the system up to full capacity.
  11. Continue to add coolant until the level stabilizes just below the radiator filler neck, then install the pressure cap. Make sure the arrows on the pressure cap, if present, line up with the overflow tube on the radiator filler neck.
  13. After the engine has run for another 2 or 3 minutes, check to make sure the coolant has reached the MAX fill line in the surge tank. If necessary add coolant to the surge tank.


  1. Prepare 2 gallons of a flushing solution consisting of 4 ounces of Calgon®, or an equivalent automatic dishwasher detergent.
  3. Run the engine until normal operating temperature is reached and the thermostat opens; this will allow the cleaning solution to circulate through the entire cooling system.
  5. Carefully drain the engine cooling system.
  7. Fill the cooling system with the flushing solution.
  9. Run the engine for 5 minutes, then drain the flushing solution into a clean container.
  11. Repeat Steps 4 and 5 until the drained water is free of coolant and/or rust. If the cleaning solution becomes overly dirty, substitute clean water or a fresh cleaning solution.
  13. Once the system seems clean, fill the cooling system with clean water 1 last time.
  15. Run the engine for 5 minutes, then drain the water from the cooling system.
  17. Properly fill the engine cooling system with an ethylene glycol antifreeze.