Air Injection Pump: Testing and Inspection

Thermactor Air Supply Pump:

1. Accelerate engine to about 1500 rpm and observe airflow from hose(s).
If airflow increases as engine is accelerated, the pump is operating satisfactorily.
If not, proceed as follows:
2. Check for proper drive belt tension.
3. Check for leaky air pump pressure relief valve, if so equipped.
NOTE: Air may be heard leaking with the pump running. The air pump is not completely noiseless. Under normal conditions noise rises in pitch as engine speed increases. To determine if excessive noise is the fault of the system, operate the engine with the pump drive belt removed. If excessive noise does not exist with the belt removed, proceed to next step.
4. Check for proper installation of the relief valve silencer, if so equipped.
5. Check air pump for proper mounting.
6. Check for seized air pump. Air pump pulley should turn freely.
7. Check hoses, tubes for proper routing and damage. Check air manifolds and all connections for leaks, damage, and secure installation.
8. If none of the above conditions exists and the air pump has excessive noise, replace the pump.