C7 Industrial Engines Testing and Adjusting – Aftercooler – Test

Table 1
Required Tools
Part Number Part Name Quantity
Engine Pressure Group
Digital Pressure Indicator
FT-1984 Aftercooler Testing Group 1
FT-1438 Aftercooler Gp (DYNAMOMETER TEST) 1

Visual Inspection

Inspect the following parts at each oil change:


  • Air lines
  • Hoses
  • Gasket joints

Ensure that the constant torque hose clamps are tightened to the correct torque. Check the welded joints for cracks. Ensure that the brackets are tightened in the correct positions. Ensure that the brackets are in good condition. Use compressed air to clean any debris or any dust from the aftercooler core assembly. Inspect the cooler core fins for the following conditions:


  • Damage
  • Debris
  • Corrosion

Use a stainless steel brush to remove any corrosion. Ensure that you use soap and water.

Note: When parts of the air-to-air aftercooler system are repaired, a leak test is recommended. When parts of the air-to-air aftercooler system are replaced, a leak test is recommended.

The use of winter fronts or shutters is discouraged with air-to-air aftercooled systems.

Inlet Manifold Pressure

Normal inlet manifold pressure with high exhaust temperature can be caused by blockage of the fins of the aftercooler core. Clean the fins of the aftercooler core. Refer to “Visual Inspection” for the cleaning procedure.

Low inlet manifold pressure and high exhaust manifold temperature can be caused by any of the following conditions:

Plugged air cleaner – Clean the air cleaner or replace the air cleaner, as required. Refer to the Operation and Maintenance Manual, “Engine Air Cleaner Element (Dual Element) – Clean/Replace”.

Blockage in the air lines – Blockage in the air lines between the air cleaner and the turbocharger must be removed.

Aftercooler core leakage – Aftercooler core leakage should be pressure tested. Refer to “Aftercooler Core Leakage” topic for the testing procedure.

Leakage of the induction system – Any leakage from the pressure side of the induction system should be repaired.

Inlet manifold leak – An inlet manifold leak can be caused by the following conditions: loose fittings and plugs, missing fittings and plugs, damaged fittings and plugs and leaking inlet manifold gasket.

Aftercooler Core Leakage

Illustration 1 g01134323
FT-1984 Aftercooler Testing Group

(1) Regulator and valve assembly

(2) Nipple

(3) Relief valve

(4) Tee

(5) Coupler

(6) Aftercooler

(7) Dust plug

(8) Dust plug

(9) Chain

A low power problem in the engine can be the result of aftercooler leakage. Aftercooler system leakage can result in the following problems:


  • Low power
  • Low boost pressure
  • Black smoke
  • High exhaust temperature

A large leak of the aftercooler core can often be found by making a visual inspection. To check for smaller leaks, use the following procedure:


  1. Disconnect the air pipes from the inlet and outlet side of the aftercooler core.



Dust plug chains must be installed to the aftercooler core or to the radiator brackets to prevent possible injury while you are testing. Do not stand in front of the dust plugs while you are testing.


  1. Install couplers (5) on each side of the aftercooler core. Also, install dust plugs (7) and (8). These items are included with the FT-1984 Aftercooler Testing Group.Note: Installation of additional hose clamps on the hump hoses is recommended in order to prevent the hoses from bulging while the aftercooler core is being pressurized.



Do not use more than 240 kPa (35 psi) of air pressure or damage to the aftercooler core can be the result.


  1. Install the regulator and valve assembly (1) on the outlet side of the aftercooler core assembly. Also, attach the air supply.


  1. Open the air valve and pressurize the aftercooler to 205 kPa (30 psi). Shut off the air supply.


  1. Inspect all connection points for air leakage.


  1. The aftercooler system’s pressure should not drop more than 35 kPa (5 psi) in 15 seconds.


  1. If the pressure drop is more than the specified amount, use a solution of soap and water to check all areas for leakage. Look for air bubbles that will identify possible leaks. Replace the aftercooler core, or repair the aftercooler core, as needed.



To help prevent personal injury when the tooling is removed, relieve all pressure in the system slowly by using an air regulator and a valve assembly.


  1. After the testing, remove the FT-1984 Aftercooler Testing Group. Reconnect the air pipes on both sides of the aftercooler core assembly.

Air System Restriction

Pressure measurements should be taken at the inlet manifold (10) and at the turbocharger outlet (11) .

Use the differential pressure gauge of the 1U-5470 Engine Pressure Group or use the 198-4240 Digital Pressure Indicator. Use the following procedure in order to measure the restriction of the aftercooler:


  1. Connect the vacuum port of the differential pressure gauge to port (10) .


  1. Connect the pressure port of the differential pressure gauge to port (11) .


  1. Record the value.

The air lines and the cooler core must be inspected for internal restriction when both of the following conditions are met:


  • Air flow is at a maximum level. 
  • Total air pressure drop of the charged system exceeds 16.9 kPa (5 in Hg). 

If a restriction is discovered, proceed with the following tasks, as required:


  • Clean 
  • Repair 
  • Replacement 

Turbocharger Failure

If a turbocharger failure occurs, remove the air-to-air aftercooler core. Internally flush the air-to-air aftercooler core with a solvent that removes oil and other foreign substances. Shake the air-to-air aftercooler core in order to eliminate any trapped debris. Wash the aftercooler with hot, soapy water. Thoroughly rinse the aftercooler with clean water and blow dry the aftercooler with compressed air. Blow dry the assembly in the reverse direction of normal air flow. To make sure that the whole system is clean, carefully inspect the system.


Do not use caustic cleaners to clean the air-to-air aftercooler core.

Caustic cleaners will attack the internal metals of the core and cause leakage.

Dynamometer Test

In hot ambient temperatures, chassis dynamometer tests for models with an air-to-air aftercooler can add a greater heat load to the jacket water cooling system. Therefore, the jacket water cooling system’s temperature must be monitored. The following measurements may also need a power correction factor:


  • Inlet air temperature 
  • Fuel API rating 
  • Fuel temperature 
  • Barometric pressure 

With dynamometer tests for engines, use the FT-1438 Aftercooler Gp (DYNAMOMETER TEST). This tool provides a water cooled aftercooler in order to control the inlet air temperature to 43 °C (110 °F).

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