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STEP 1
With the engine off, top off the engine coolant level with premixed coolant.
STEP 2
With the engine off, connect the radiator pressure tester in place of the pressure cap. Larger caps, which are found on HD cooling systems, or unique OEM pressure cap designs may not fit with a standard pressure cap tester. An adapter may be required to seal the tool to the neck of the surge tank or radiator.
STEP 3
Pressurize the system to 15–17 psi (103–117 kPa).
STEP 4
Observe the pressure readings for 30 minutes. During this time, visually inspect the cooling system hoses, all the connections, auxiliary coolant heaters, bunk and cab heaters, EGR coolers, EGR valves, turbocharger coolant lines, the water pump weep hole, all gasket sealing surfaces, and any other components that have coolant flow.
STEP 5
Check the engine oil level and verify that the oil has a normal color. Oil that looks milky likely has coolant leaking into it. Verify that coolant is not leaking into the oil by sampling and performing an oil analysis.
STEP 6
Inspect the seals on the pressure cap and pressure test the cap. The seals should be intact and in good condition without any cracks. The same pressure tester used to test the engine is also used to test the cap. Place an adapter between the cap and the test tool and pump the tester once again. The cap’s release pressure should be indicated on the cap, and it should hold pressure until the tester applies the amount of pressure specified on the cap.
STEP 7
Refer to the OEM service information to check whether the pressure cap is correctly rated for the vehicle. If the cap will not hold or cannot reach specified pressure, or if it does not vent at the specified pressure, then replace it with a new cap with the correct pressure rating.
STEP 8
Record and report your results.
STEP 9
If there is a significant drop in pressure and the complaint is related to coolant loss, the engine may have an internal coolant leak. Using a separate procedure, the engine should be checked first to determine whether the cooling system is excessively pressurized when operating. The EGR cooler should be inspected as well using a separate procedure.
STEP 10
To check for internal leaks, drain the engine oil and remove the oil pan.
STEP 11
With the cooling system still pressurized, observe whether the liner O-rings are leaking or whether coolant is emerging from a head gasket leak. In pushrod engines, head gasket leaks drip coolant from the cam side of the engine.
STEP 12
Remove the EGR outlet hose or tube and inspect for the presence of coolant.
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