Temperature Gauge - Needle Fluctuation
Number 84-6 (Gasoline)43 Date 6/84Subject: TEMPERATURE GAGE NEEDLE FLUCTUATION 1984 FIERO VEHICLES
Some temperature gage needle fluctuation is normal during warm up. If the gage continues to fluctuate between 180~F and 220~F after the engine is completely warm (15 minutes of driving), the following items should be checked.
1. Verify that the coolant level is correct.
2. Check cooling fan operation.
3. Verify gage operation using CCC-EFI scan tool. If the condition persists after verifying the above, the heater core may be partially plugged. Drain the cooling system, remove the heater hoses at the heater connections, and back flush the core.
IMPORTANT: When refilling the cooling system on the Fiero, it should be completely filled and the reservoir filled to 1/2" from top. The engine should be warmed until engine cooling fan comes on (heater in Off mode), allowed to cool down and refilled as necessary. Keep the coolant level in the overflow reservoir well above the cold level as the system may continue to take in coolant for one or two more heating cycles.