Coolant Temperature Rises Too High (Overheating) - Komatsu PC88MR-10 Shop Manual

40 Troubleshooting
Troubleshooting of engine (S-mode)
S-17 Coolant temperature rises too high (overheating)

Coolant temperature rises too high (overheating).

Failure
Related
If any failure code is displayed, perform troubleshooting for that code first.
information
No. Cause
Clogged radiator core
1
2 Malfunction of thermostat
Defective coolant
3
temperature gauge
Increased fuel injection rate
4
5 Low coolant level
Leakage of coolant
6
Breakage of water pump
7
Overheating due to increased
EGR ratio (EGR amount
against fresh air amount)
8
caused by defective mass air
flow and temperature sensor
Overheating due to increased
EGR ratio (EGR amount
9 against fresh air amount)
caused by air cleaner
deformation
Defective cylinder head or
10
cylinder head gasket
11 Defective piston ring
40-536
Point to check, remarks
Check radiator core for clogging, and check
fin for crush.
Thermostat does not open at cracking
temperature.
a Thermostat cracking temperature
Primary valve: 76ºC
Secondary valve: 83ºC
(Full open temperature: 95°C)
Error related to coolant temperature is
displayed, but measured value of radiator
coolant temperature is normal.
Fuel injection rate is high.
Check coolant level for lowering
Check water leakage from coolant piping
Visually check water pump
(Check shaft seal for water leakage,
impeller for damage,
breakage.)
Check mass air flow and temperature
sensor.
Check air cleaner for deformation and
presence.
Check radiator coolant for excessive
bubbles and spurt back
Open exhaust color inspection hole for the
KDOC muffler outlet, and check exhaust
gas.
(Reference: See Testing and adjusting,
"Testing exhaust gas color".)
Measure compression pressure (see
Standard value table).
(Reference: See Testing and adjusting,
"Testing compression pressure".)
Check piston ring and piston ring groove.
(PC88MR-AL0-400-A-Z0-A)
Clean radiator core.
Replace thermostat.
Replace coolant
temperature sensor,
monitor or wiring
harness.
Perform
troubleshooting for "S-
12 Fuel consumption is
excessive".
Refill with coolant
Replace coolant piping
Replace water pump.
and shaft for
Replace mass air flow
and temperature
sensor.
Repair or replace air
cleaner.
Perform
troubleshooting for "S-
13 Oil is in coolant".
Replace piston ring or
piston.
Remedy
PC88MR-10