GMC 1976 ZEO 6083 Maintenance Manual page 337

6K- 6
ENGINE COOLING
1 . Apply a thin coat of 1050026 Sealer or equiva-
lent to the pump housing to retain the new gasket,
then position on the housing.
2. Install the pump assembly . Coat all bolts withl
engine oil and torque the self-tapping bolts to 13 ft .
lbs . and torque the others to 25 ft . lbs.
3 . Connect the power steering pump bracket and
the L.H . upper venturi ring bracket. Torque nut to
22 ft. lbs.
lbs.
INSTALLATION
4. Install venturi ring and torque nuts to 25 ft .
5 . Install water pump pulley . Reposition all belts.
The thermostat consists of a restriction valve ac-
tuated by a thermostatic element. A 195° thermostat
is used and the use of thermostats rated above 195
degrees F (90°C) control temperatures are not
recommended. This is mounted in the housing at the
cylinder head water outlet above the water pump .
The thermostat should be installed with the word
FRONT up and toward the radiator . This way the
Figure 7-Fan Installation
THERMOSTAT
6. Install fan and fan clutch assembly . Torque
four (4) nuts to 15 ft . lbs. (See figure 6) .
7. Reposition shroud to venturi ring seal over
venturi ring .
8. Install venturi ring seal strap.
9. Connect lower radiator hose to water pump .
10 . Lower motor home .
11 . Secure clamp on bypass hose and install
heater hose to water pump .
12 . Tension belts. Refer to "Belt Tension" later
in this section.
13 . Refill radiator . If new coolant is used refer to
Section 0.
coolant has a smooth unobstructed flow through the
thermostat and water outlet . See Figure 7.
When the thermostat is incorrectly installed, as
in "B" shown in Figure 7, the thermostat valve acts
as a baffle, forcing the coolant to change direction to
pass around the valve. This change in direction inter-
rupts the smooth unobstructed flow of coolant to the
radiator and can possibly result in overheating con-
ditions.
Thermostats are designed to open and close at
predetermined temperatures and if not operating
properly should be removed and tested .
An operational check of the thermostat can be
made by hanging thermostat on a hook in a 33%
glycol solution at 220°F (104 .4°C). Submerge the
valve completely and agitate the solution
thoroughly . Under this condition the valve should
open . Remove the thermostat and place in a solution
of 33% glycol solution at 185°F (85°C) . With the
valve completely submerged and the solution agi-
tated thoroughly, the valve should close completely .