Pontiac Fiero 1984-1988 Repair Guide

Cooling System



Click image to see an enlarged view

Fig. Fig. 1 Location of the coolant recovery bottle

A see-through plastic reservoir called a coolant recovery bottle, is located in the front compartment near the radiator assembly. This bottle is connected to the radiator by a hose. As the car is driven, the coolant is heated and expands, the portion of the fluid displaced by this expansion flows from the radiator into the recovery bottle. When the car is stopped and the coolant cools and contracts, the displaced coolant is drawn back into the radiator by vacuum. Thus, the radiator is kept filled with coolant to the desired level at all times. The coolant level should be between the "ADD" and "FULL" marks on the recovery bottle. If coolant is needed, add it to the recovery bottle not the radiator. The "ADD" and "FULL" marks on the recovery bottle are approximately one quart apart so that a 50/50 mixture can be added (50% ethylene glycol antifreeze and 50% water).

Do not remove the radiator cap or the thermostat housing cap while the engine and radiator are still hot. This also includes the recovery bottle cap if coolant in the recovery bottle is boiling. Scalding fluid and steam can be blown out under pressure if any cap is taken off too soon.

The engine cooling fan is electric and can come on whether or not the engine is running. The fan can start automatically in response to a heat sensor when the ignition is in "Run." Remember to keep hands, tools and clothing away from the cooling fan when working under the compartment lid.


Click image to see an enlarged view

Fig. Fig. 2 Radiator drain valve components

Click image to see an enlarged view

Fig. Fig. 3 Check all the labels and read all the instructions before attempting to drain and refill the cooling system

Click image to see an enlarged view

Fig. Fig. 4 After the engine has cooled remove the radiator cap

Click image to see an enlarged view

Fig. Fig. 5 Use an allen wrench to loosen the drain plug ...

Click image to see an enlarged view

Fig. Fig. 6 ... then let the coolant drain into a suitable container

Click image to see an enlarged view

Fig. Fig. 7 After all the old coolant has been drained and the drain plug closed, refill the system with the proper mix and amount of coolant

When draining engine coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain coolant into a sealable container. Coolant should be reused unless it is contaminated or is several years old.

The cooling system should be drained and refilled every 24 months or 30,000 miles. Please read the Cautions above then perform the following procedure:

Use a good quality antifreeze with water pump lubricants, rust inhibitors and other corrosion inhibitors along with acid neutralizers. Use a permanent type coolant that meets manufacturer's specifications.

  1. When the engine is cool, open the rear engine compartment lid and turn the thermostat housing cap slowly counterclockwise until it reaches a stop.

Do not press down while turning the cap.

  1. Wait until any remaining pressure is relieved, then press down on the cap and continue turning it counter-clockwise. Remove the cap.
  3. Pull the thermostat straight out then install the cap. Run the engine at least one minute to circulate the coolant.
  5. Stop the engine, then open the radiator drain valve, located on the bottom of the radiator side tank, and drain the coolant.

You may speed up drainage by removing the drain plugs in the engine block and in the left and right coolant pipes. The coolant pipes run underneath the car. The coolant pipe plugs are located at the rear of each pipe just ahead of the rear tires. The engine block drain plug is located on the front of the engine, on the driver's side, just above the starter.

  1. Run water through the thermostat opening until the drained liquid is nearly colorless.
  3. Install all drain plugs and close the radiator drain valve.
  5. Remove the radiator cap and add water through the thermostat housing until the water reaches the level of the radiator neck.
  7. Install the radiator and thermostat housing caps.

Do not install the thermostat at this time.

  1. Tighten the thermostat housing cap to the first notch. At this point you should hear a clicking sound, and you will not be able to turn the cap counterclockwise without pushing it down.
  3. Run the engine until the hose connected to the thermostat becomes hot. Drain the system again.
  5. Install all drain plugs and close the radiator drain valve.
  7. Remove, drain and clean the coolant recovery bottle, then install.
  9. Add the correct amount of water and ethylene glycol antifreeze to provide the required cooling, freezing and corrosion protection. Use a solution that contains at least 50% antifreeze but not more than 70% antifreeze.
  11. With the engine off, remove the radiator cap. Add coolant through the thermostat housing until the coolant reaches the spill point of the radiator neck.
  13. Install the radiator and thermostat housing caps, but do not install the thermostat at this time. Tighten the thermostat housing cap as in Step 9.
  15. Add approximately 3 qts. of coolant to the coolant reservoir bottle.
  17. Run the engine at normal idle for 3 minutes, then at fast idle for 15 or 20 seconds. Turn the engine off.
  19. Refer to Steps 1 and 2 and remove the thermostat housing cap. Add coolant to the thermostat housing until it reaches the housing cap seat.
  21. Install the thermostat and cap. Make sure the thermostat is fully seated and the arrows on the cap line up with the coolant hose at the thermostat housing.
  23. After driving the car for the first time after changing the fluid, let the engine cool then add coolant to the coolant recovery bottle as necessary to bring it to the proper level.


Click image to see an enlarged view

Fig. Fig. 8 Cooling systems should be pressure tested for leaks periodically

Click image to see an enlarged view

Fig. Fig. 9 Be sure the rubber gasket on the radiator cap has a tight seal

Click image to see an enlarged view

Fig. Fig. 10 Periodically remove all debris from the radiator fins

Most permanent antifreeze/coolant have a colored dye added which makes the solution an excellent leak detector. When servicing the cooling system, check for leakage at:

All hoses and hose connections
Radiator seams, radiator core, and radiator draincock
All engine block and cylinder head freeze (core) plugs, and drain plugs
Edges of all cooling system gaskets (head gaskets, thermostat gasket)
Transmission fluid cooler
Heating system components, water pump
Check the engine oil dipstick for signs of coolant in the engine oil. Will turn the oil a white color
Check the coolant in the radiator for signs of oil in the coolant

Investigate and correct any indication of coolant leakage.

Check the Radiator Cap

While you are checking the coolant level, check the radiator 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.

Clean Radiator of Debris

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.


A 50/50 mix of coolant concentrate and water will usually provide protection to -35°F (-37°C). Freeze protection may be checked by using a cooling system hydrometer. Inexpensive hydrometers (floating ball types) may be obtained from a local department store (automotive section) or an auto supply store. Follow the directions packaged with the coolant hydrometer when checking protection.