NOTE
There are areas where approved
fuel (less than 0.5% sulfur) is not
commercially available or econom-
ically feasible to obtain. It is im-
portant to keep the engine cooling
system temperature of these en-
gines on the high side of normal to
prevent the condensation of sulfur
trioxide gas, which combines with
combustion water to form sulfuric
acid. Therefore, install a 180 or
190F (82 or 88C) temperature
thermostat and modify the cooling
system to provide rapid warm-up
in order to maintain coolant tem-
perature at a minimum of 175F
(80C).
R e m o v e Thermostat
1. Drain the cooling system to the neces-
sary level by opening the drain valve.
F i g u r e 11F-11. Method of Checking
Thermostat Operation
2. Remove the bolts which secure the
outlet elbow and the thermostat housing
2. Place a thermometer in the container
(bypass tube) to the water manifold
using care not to allow the thermometer
to touch the bottom or sides of the con-
tainer.
3. Remove the thermostat and clean the
outlet elbow.
3. While slowly agitating the water to
maintain an even temperature, apply heat
to
the
container.
As
the
water
is
heated, the thermostat should begin to
Inspection
open (the opening temperature is usually
stamped on the thermostat). The ther-
If the action of the thermostat has be-
mostat should be fully open at
come impaired due to accumulated rust
approximately 185 - 195F (85 - 91C)
and corrosion from the engine coolant so
Allow at least 10 minutes for the thermo-
that it remains closed, or only partially
stat to react.
open, thereby restricting the flow of coo-
lant, overheating of the engine will re-
sult. A thermostat which is stuck in the
I n s t a l l Thermostat
wide open position may not permit the
engine to reach its normal operating tem-
perature. The incomplete combustion of
fuel due to cold operation will result in
1. Affix a new gasket to each side of the
build-up of carbon deposits on the pis-
thermostat housing.
tons, rings and valves.
2. Set new gasket and the thermostat in
Check the operation of a thermostat as
the housing. Attach the outlet elbow
follows:
and the thermostat housing to the water
manifold.
1. Immerse the thermostat in a container
of
water
3. Connect any other piping which may
have been disconnected.
4. Fill the cooling system and check for
leaks.
