The operating pressure of the cooling system and the lubricating system can result in the mixing of the fluids if
there is a leak between the systems: cylinder head gasket, lubricating oil cooler, etc.
Transmission/power steering/hydraulic fluid can also leak into the coolant through radiator fluid coolers, if equipped.
Refer to the OEM service manual.
Check the coolant level and fill if necessary. Refer to Procedure 008-018 in Section 8.
To aid in determining the location of the coolant leak, it may be necessary to add fluorescent tracer, Part Number
3377438, to the coolant.
Add one unit of fluorescent tracer to each 38 liters [1 0 gal] of coolant.
Idle the engine for 5 to 1 0 minutes or until normal operating temperature is reached, to allow the dye to
circulate through the cooling system.
Use a high intensity black light, Part Number 3163337 or equivalent, to illuminate the dye.
If the radiator is equipped with a pressure relief valve, plug the overflow line (1 ).
Install the pressure tester on the radiator fill neck or surge tank, if equipped, and apply air pressure.
The Coolant DamTM/Pressure Tester service tool, Part Number 3824319, can also be used to pressurize the
cooling system. The Coolant Damm/Pressure Tester uses shop air rather than a hand air pump.
For external coolant leaks, inspect the exterior of the engine and repair if necessary.
Pay close attention to areas around the:
• Lubricating oil cooler. Refer to Procedure 007-003 in Section 7.
• Water pump. Refer to Procedure 008-062 in Section 8.
• Air compressor head gasket. Refer to Procedure 012-014 in Section 12.
• Cup plugs. Refer to Procedure 017-002 in Section 17.
• Pipe plugs. Refer to Procedure 017-007 in Section 17.
• EGR cooler. Refer to Procedure 011-019 in Section 11.
• EGA coolant lines. Refer to Procedure 011-031 in Section 11.
• Variable geometry turbocharger. Refer to Procedure 010-033 in Section 10.
• Variable geometry turbocharger coolant lines. Refer to Procedure 010-041 in Section 10.
For internal coolant leaks, inspect the interior of the engine. It may be necessary to remove the following components to look for signs of a coolant leak:
• Rocker lever cover. Refer to Procedure 003-011 in Section 3.
• Lubricating oil pan. Refer to Procedure 007-025 in Section 7.
• Turbocharger oil drain line. Refer to Procedure 01 0-045 in Section 10.
For suspected fuel in the coolant or coolant in the fuel, disconnect the fuel drain connection at the rear of the
cylinder head. Refer to Procedure 006-013 in Section 6.
Coolant Pressure Check
Measure the coolant pressure at the coolant tap number 5 or coolant tap number 6 on the exhaust side of the
cylinder head.
Coolant pressure can be affected by the following:
• Radiator pressure cap
• Debris in the cooling system
• OEM cooling options such as in-cab heaters and torque converter cooling
• Air in the cooling system
• Incorrect initial cooling system fill
• Less than 50/50 antifreeze mixture
• Engine operation at high altitude.
If the cylinder head coolant pressure is less than 138 kPa [20 psi] at high idle and without a pressure cap, do the
following:
• Check the belt tension and condition.
• Remove the water pump, inspect the impeller integrity and check for slippage on the shaft. Refer to Procedure
008-062 in Section 8.
