Start the engine and run until the coolant temperature reaches normal operating temperature. Once the coolant
has reached operating temperature, shut the engine down and completely drain the vehicle air system.
Disconnect the discharge pipe from the air compressor cylinder head.
Disconnect the air inlet plumbing at the air compressor cylinder head.
Connect to the airthe compressor oil carryover cylinder test tool, head Part discharge Number port. 4918883,
NOTE: If the application presents restricted access to the air compressor, a high temperature flexible hose
(minimum 15 mm [0.6 in] inside diameter) may be connected directly to the discharge port of the compressor, in order to carry out the test outside the engine compartment.
Install the test paper into the service tool, Part Number 4918883. Make sure it is held at a right angle to and in line
with the flow of compressed air, at a distance, not to exceed 100 mm [3.9 in] from the end of the compressor
discharge pipe, or flexible hose, if fitted.
The test paper can be standard clean copier paper, typically 80 grams/sq meter. It must be mounted in the air
compressor discharge line tool, leaving a 70 mm [2. 76 in] diameter circle of the paper exposed. The outline of the
circle in the mask must be drawn onto the test paper to later aid in comparison.
NOTE: It may be necessary to use INSITE’M electronic service tool to increase the maximum engine speed,
without VSS, to 2100 rpm.
To perform the test, start the engine and run at high idle.
Leave the test paper in the airflow for exactly 5 minutes.
Remove the test paper, or rotate the tool mask exposing a new circular test area.
Repeat this test until 3 comparable circular test areas are generated.
Shut the engine down.
NOTE: If the maximum engine speed, without VSS, was adjusted in the previous step, change it back to the
original value upon completion of the test.
NOTE: Compare the test results with the reference results shown below.
Time Air Compressor Has Been In Service (Months/ Years):
• Less Than 6 Months – Compressor in good condition
• 6 Months to 2 Years- Compressor in good condition
• Greater Than 2 Years- Compressor in good condition.
Time Air Compressor Has Been In Service (Months/ Years):
• Less Than 6 Months Compressor needs to be replaced
• 6 Months to 2 Years – Compressor in acceptable condition
• Greater Than 2 Years- Compressor in good condition.
Time Air Compressor Has Been In Service (Months/ Years):
• Less Than 6 Months – Compressor needs to be replaced
• 6 Months to 2 Years – Compressor needs to be replaced
• Greater Than 2 Years – Compressor needs to be replaced.
