The thermostat can be tested by the following

ENGINE

compression gauge in first spark plug hole and hold it

the bellows for rupture or distortion. If the valve can be

firmly. (Fig. 67)

pulled or pushed off its seat with only a slight effort

when cold or it does not seat properly, the unit is

defective and must be replaced.

2. The thermostat can be tested by the following

method:

a. Hang thermostat by its frame in a

container of water so that it does not

touch the bottom.

b. Heat the water and check temperature

with a thermometer.

c. If the valve of a 180thermostat does not

start to open at temperature of 165-

1750F, or if it opens well before the 1650

point is reached, the thermostat should be

replaced. Thermostat should be fully

open between 1800 and 1850. When

checking thermostats of different rating,

the foregoing temperatures will vary

accordingly.

When replacing the

thermostat, be sure seal is in place and

Figure 67.

seal seat, as well as counterbore, is clean.

Assemble new gasket to housing contact

Crank engine until the highest gauge reading is

surface. Thermostat flange must seat in

obtained. Check all cylinders in this manner. If

counterbore with gasket sealing contact

readings are low in two adjacent cylinders, a blown head

between it and the cover.

gasket is indicated. If readings are low and vary widely

(more than 10 PSI), pressure is being lost either at the

F. FAN BELT

pistons, rings or valves. To determine where pressure

loss is occurring, insert about one tablespoon of SAE 30

When tightening fan belts, loosen the alternator

engine oil through the spark plug hole. Take a new

mounting and adjusting bolts and pull out on the

reading. If this reading is higher than the initial reading,

alternator by hand until the belt is just snug. Under no

the piston rings are faulty. If reading is the same as the

consideration should a pry bar be used on the alternator

initial reading, the valves may be leaking or the cylinder

to obtain fan belt tension or damage to the bearings will

head gasket is damaged.

result. When adjusted correctly, the fan belt should

have between 1/2 inch deflection on the long side.

H. ADJUST VALVE TAPPET CLEARANCE

Tighten alternator mounting and adjusting bolts when

adjustment is completed.

Check and adjust if necessary to specified clearance

both intake and exhaust valves after the engine has

G. COMPRESSION

warmed up to running temperature. Turn the adjusting

screws in or out until the correct feeler gauge clearance

Warm up engine to operating temperature. Remove all

is obtained.

spark plugs and block throttle wide open.

Insert

B-25