Tests For The Air Inlet Heater
| |
| Illustration 1 | g00910925 |
|
(1) Electrical connection
(2) Fuel inlet (3) Ball valve (4) Valve holder (5) Wire coil (6) Ignition coil | |
The air inlet heater (1) is located in the air inlet manifold on the right side of the engine.
The air inlet heater frequently appears to leak because the ignition coil (9) is wet. The air inlet heater may be wet because the diesel fuel does not burn completely. This condition is normal. This condition does not indicate that the ball valve (6) has fuel leakage. If a leak is suspected, perform the leakage test.
Check the heater operation by determining if the inlet manifold is warm to the touch near the heater after approximately ten seconds of operation. The inlet manifold should be warm.
Inspect the fuel tank and the fuel supply line (2) to the air inlet heater for restrictions and leakage of fuel. Fuel flow through the heater should be 3.5 to 5.9 cc/min (0.21 to 0.36 cu in/min).
Check the fuel shutoff valve for correct operation. A poor seal on the fuel shutoff valve can cause air to enter the system which will cause extra cranking of the engine before starting. Be sure that all fuel connections are not leaking air.
Make sure that the battery condition and the battery charge are satisfactory. Make sure that all electrical connections are tight. The electrical system can have reduced voltage if the following conditions exist:
- A discharged battery
- A loose connection
Reduced voltage may cause slow cranking of the starter motor and failure of the heater unit to be activated.
| NOTICE |
|---|
|
If operated for a long period of time, The air inlet heater can create excessive heat. Excessive heat can damage the air inlet heater. |
Leak Test For The Air Inlet Heater On The Engine
Use the following procedure in order to test for a leak in the air inlet heater.
- Disconnect the fuel supply line (2) and the electrical connection on the air inlet heater. Be sure that the electrical connector is insulated from contact with metal engine components. Remove the air inlet heater from the manifold. Place a suitable plug in the manifold in order to prevent debris from entering the air inlet manifold.
- Connect the fuel supply line to the air inlet heater. Loosely tighten the connection fitting. Operate the priming lever of the fuel transfer pump until only fuel which is free of air flows from the connection. Tighten the connection fitting.
Show/hide table
Work carefully around an engine that is running. Engine parts that are hot, or parts that are moving, can cause personal injury.
- Start the engine and operate the engine at low speed. Check that there is no fuel leakage from the valve of the air inlet heater.
- If leakage exists, the air inlet heater must be replaced. If no fuel leakage occurs, remove the plug from the inlet manifold and disconnect the fuel supply line from the air inlet heater. Install the air inlet heater in the air inlet manifold. Connect the fuel supply line to the heater. Operate the priming lever of the fuel transfer pump until only fuel which is free of air flows from the connection. Connect the electrical wire connector.
Leak Test For The Air Inlet Heater Off The Engine
Use this test in order to test for leakage of fuel in the air inlet heater if a pressurized air supply is available.
| NOTICE |
|---|
|
The air inlet heater may be damaged if more than |
- Remove the air inlet heater from the inlet manifold. Connect an air supply to the fuel inlet passage. The maximum pressure of the air supply should be
140 kPa (20 psi) . - Put the air inlet heater in a container of clean diesel fuel for ten seconds. No air bubbles should be visible from the air inlet heater. If the air inlet heater is not faulty, remove the fuel from the air inlet heater. Reinstall the air inlet heater in the air inlet manifold. If leakage of air occurs, install a new air inlet heater.
|
|
Pressurized air can cause personal injury. When pressurized air is used for cleaning, wear a protective face shield, protective clothing, and protective shoes. |
| Tools Needed | ||
| Part Number | Part Name | Quantity |
| 5P-7277 | Voltage Tester | 1 |
| 8T-0900 | Ammeter | 1 |
Conduct this test in order to determine if sufficient electrical current is provided to the air inlet heater for proper operation.
- Disconnect the electrical wire from the air inlet heater.
- Connect the clamp lead of a 5P-7277 Voltage Tester to a good ground connection.
- Connect the probe end of the tester to the disconnected electrical wire.
- The light of the tester turns on in order to indicate that electrical continuity to the air inlet heater exists.
- Connect a 8T-0900 Ammeter between the electrical supply and the air inlet heater. Turn the ignition switch to the ON position. Activate the switch for the air inlet heater. The normal current is 16 to 18 amperes at 12 volts.
Note: A cold engine should start after the heater coil has operated for 20 seconds. If the engine does not start but the air inlet heater and the area of the inlet manifold around the air inlet heater are warm, either the starting procedure has not been done correctly or the problem is not caused by the air inlet heater.