Service Manual

ISB, ISBe and QSB (Common Rail [...] Cooling System Diagnostics
Section 8 - Cooling System - Group 08 Page 8-49
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Cooling System Diagnostics (008-020)
General Information
The following procedure covers common troubleshooting
steps to help identify:
• Engine overheat causes. See the Initial Check step of
this procedure.
NOTE: At the end of this procedure, a worksheet is
provided to record any measured values taken during
troubleshooting. The worksheet will help in gathering and
analyzing the data.
• External and internal coolant leaks/loss. See the
Pressure Test step of this procedure.
• Combustion gas leaks into the cooling system. See the
Test step of this procedure.
If the coolant reaches an unacceptable level in the
recovery/expansion tank, a fault code should become
active that will illuminate an instrument lamp and impose a
power derate. This low level is detected by a coolant level
switch mounted in the coolant surge/recovery tank.
In the event of a cooling system-related malfunction, it is
recommended that coolant level switches be checked for
proper operation. Refer to the OEM service manual for
operational checks and repairs.
Removal and installation of the coolant level switch for
diagnostics is NOT recommended. This poses a high
likelihood of damage due to the plastic construction of the
switch. The coolant level switch must only be removed
from the surge/recovery tank when replacing with a new
switch. Be certain not to over tighten the switch when
installing. Most switches have a very low torque value,
which can be found in the OEM service manual.
Coolant level switches are very susceptible to improper
Ph levels. For this reason, it is imperative that coolant be
maintained in accordance with Cummins® Coolant
Requirements and Maintenance, Bulletin 3666132.
Initial Check
Connect an electronic service tool to the vehicle's data
link.
Turn the keyswitch to the ON position.
Monitor the coolant temperature with the electronic
service tool.