High Temperature Shutdown Switch - Toro Groundsmaster 4500-D Service Manual

High Temperature Shutdown Switch

The high temperature shutdown switch is located near
the glow plug connection on the engine cylinder head
(Fig. 36). There is a blue/white wire attached to the
switch.
The high temperature shutdown switch is designed to
shut the engine off when engine coolant temperature
reaches an unsafe level. If problems with the switch sys-
tem are encountered, the following procedure can be
used to determine if the problem is related to the switch
or the switch circuit:
1. Start engine.
2. Use a jumper wire to ground the high temperature
shutdown switch terminal.
3. Engine should stop running indicating that the switch
circuit is functioning correctly. If the engine continues
running with the grounded jumper wire, the switch circuit
needs repair.
Shutdown Switch Test
Make sure engine is cool before removing the
temperature switch.
1. Lower coolant level in the engine and remove the
temperature shutdown switch.
2. Put switch in a container of oil with a thermometer
and slowly heat the oil (Fig. 37).
Handle the hot oil with extreme care to prevent
personal injury or fire.
3. Check continuity of the switch with a multimeter
(ohms setting). The temperature switch is normally
open and should close between 225
o
113 C).
4. Allow oil to cool while observing temperature. The
temperature switch should open at about 219
o
(104 C).
5. Replace switch if necessary.
Groundsmaster 4500--D/4700--D
CAUTION
CAUTION
o o o
to 235 F (107
o
Page 5 - - 23
2
1. High temperature shutdown switch
2. Glow plug connection
6. Install switch to the water flange.
A. Clean threads of cylinder head and switch thor-
oughly. Apply thread sealant to the threads of the
switch.
B. Screw switch into the cylinder head and tighten.
C. Connect blue/white wire to switch.
7. Fill engine cooling system (see Traction Unit Opera-
tor's Manual).
to
F
1
Figure 36
VOA
Figure 37
Electrical System (Rev. A)