Hot Engine Test

HOT ENGINE

NOTE: As the outside air temperature drops, the bimetal spring in the bleed valve closes, causing the air control door to rise and allowing pre-heated air into the air cleaner; consistent intake air temperature (approximately 100°F) is maintained in this way.





1. With the engine running and the cooling fan on, disconnect the air intake duct from the air cleaner case and immediately check the control door position.
The air control door should be down.
- If the control door has dropped down to fully close the hot air intake duct: stop the engine and reconnect the air intake duct. Test is complete.
- If the control door has not dropped to the fully closed position, go on to step 2.
2. Disconnect the vacuum hose from the air control diaphragm.
- If the control door now closes, replace the air bleed valve and retest.
- If the control door does not close, correct whatever is causing the door to bind, and/or replace the air control diaphragm. Retest.
3. Stop the engine and reconnect the air intake duct. Test is complete.