Cummins N14 STC, Celect, Celect Plus – Service Manual 010-027   Charge-Air Cooler

If the engine experiences a turbocharger malfunction or any other occasion where oil or debris enters the charge-air cooler, the charge-air cooler must be cleaned.

Remove the charge-air cooler from the vehicle. Refer to the OEM service manual.

WARNING  When using solvents, acids, or alkaline materials for cleaning, follow the manufacturer’s recommendations for cleaning. Wear goggles and protective clothing to reduce the possibility of personal injury.

CAUTION  Do not use caustic cleaners to clean the charge-air cooler. Damage to the charge-air cooler will result.

Flush the charge-air cooler internally with solvent in the opposite direction of normal air flow.

Shake the charge-air cooler and lightly tap on the end tanks with a rubber mallet to dislodge trapped debris. Continue flushing until all debris or oil is removed.

NOTE: Make sure that the tubes are in the vertical direction when flushing.

If the debris can not be totally removed from the charge-air cooler, the charge-air cooler must be replaced.

WARNING  Wear appropriate eye and face protection when using compressed air. Flying debris and dirt can cause personal injury.

CAUTION  The charge-air cooler must be rinsed, dried, and free of solvent, oil, and debris or engine damage will result.

After the charge-air cooler has been thoroughly cleaned of all oil and debris with solvent, wash the charge-air cooler internally with hot soapy water to remove the remaining solvent. Rinse thoroughly with clean water.

Blow compressed air into the charge-air cooler in the opposite direction of normal air flow until the charge-air cooler is dry internally.

Inspect the charge-air cooler for cracks, holes, or other damage.

Inspect the tubes, fins, and welds for tears, breaks, or other damage.

If any damage causes the charge-air cooler to fail the air leak check mentioned earlier in this procedure, the charge-air cooler must be replaced.

Install the charge-air cooler. Refer to the OEM service manual.

To check the charge air cooler for an air leak perform the following steps.

To check the charge-air cooler for cracked tubes or header, remove the inlet and outlet hoses from the cooler.

The charge-air cooler does not have to be removed from the chassis.

WARNING  To prevent possible injury if either plug blows off during the test, secure safety chains on the test plugs to any convenient capscrew on the radiator assembly. This test must not be performed without securely fastened safety chains.

Install a plug or cap on the outlet side of the cooler.

Install a pressure gauge, air supply line, and air pressure regulator to the inlet side of the cooler.

Apply 207 kPa [30 psi] of air pressure to the cooler. Close the air pressure regulator.

Determine if pressure decay is caused by a leak in the charge-air cooler or from a leaky connection.

Use a spray bottle filled with soapy water and apply to all hose connections.

Watch for bubbles to appear at the location of the leak.

If the pressure decay is caused by a leaky connection, repair the connection and repeat the test. If the leak is within the charge-air cooler, repeat the test to verify the accuracy of the pressure decay measurement. Similar pressure decay readings must be obtained in at least three consecutive tests before the reading can be considered accurate.

Monitor the pressure gauge and determine the rate of pressure decay with a stop watch.

If the pressure drop is greater than 49 kPa [5 psi] in 15 seconds, the charge-air cooler must be replaced.

Refer to the OEM service manual for replacement instructions.

If a charge-air cooler leaks more than 49 kPa [5 psi] in 15 seconds, it will appear as a major leak in a leak tank.

Charge air coolers are not designed to be 100 percent leak free. If the pressure decay is less than 49 kPa [5 psi] in 15 seconds, then the charge-air cooler does not need to be replaced.

Inspect the charge-air cooler fins for obstructions to air flow.

Remove obstructions such as a winterfront or debris. Manually lock the shutters, if equipped, in the “OPEN” position.

Lock the fan drive in the “ON” mode to prevent erratic test results. This can be done by installing a jumper across the temperature switch.

Install Fluke™ digital thermometer, Part Number 3822666, and thermocouple wire kit, Part Number 3822988, into the intake manifold at the 1/8-inch NPT tap near the air horn connection with the intake manifold.

Install another thermocouple at the air cleaner inlet to the outside of the vehicle.

Perform a road test with the engine at peak power and a vehicle speed of 30 mph or greater.

Record the intake manifold temperature and the ambient air temperature.

Calculate the differential temperature:

Intake manifold temperature – ambient air temperature = differential temperature.

If the temperature differential is greater than the specifications, check the charge-air cooler for dirt and debris on the fins and clean as necessary.

If the problem still exists, check the charge-air cooler for debris in the fins or between the charge-air cooler and the radiator.

Confirm full fan engagement.

Measure the charge-air cooler system pressure drop with a mercury manometer.

Install one end of the manometer to the 1/8-inch pipe tap in the turbocharger compressor outlet elbow.

Install the other end of the manometer to the 1/8-inch pipe tap in the intake manifold.

Operate the engine at the maximum advertised horsepower and correlating RPM.

Record the readings on the manometer.

If the differential pressure is greater than 152 mm Hg [6.0 in Hg] or 21 kPa [3 psi], check the charge-air cooler and associated piping for plugging.

Clean or replace if necessary.

Obtain two (2) pressure gauges, Part Number ST-1273.

Check both gauges on the same pressure source at 206 kPa [30 psi] to make sure of consistency.

Install pressure gauge, Part Number ST-1273, to the 1/8-inch fitting in the turbocharger compressor outlet.

Install another pressure gauge, Part Number ST-1273, into the intake manifold.

Operate the engine at the maximum advertised horsepower and correlating RPM.

Record the readings on the two gauges.

If the differential pressure is greater than 152 mm Hg [6.0 in Hg] or 21 kPa [3 psi], check the charge-air cooler and associated piping for plugging, restrictions, or other damage.

Clean or replace if necessary.