Buick LeSabre 1965 Service Manual page 50

2 - 2 8 TROUBLE DIAGNOSIS
ENGINE
check for air leaks on suction
side of pump or gas leakage from
engine may be made with a piece
of rubber tubing and a glass
bottle containing water.
1. With cooling system cold, add
water to bring coolant halfway
between core and tank top.
2. Block open the radiator cap
pressure valve, or use a plain
cap, and be sure radiator cap is
on tight. Attach a suitable length
of rubber hose to lower end of
overflow pipe.
3. Run engine in neutral at a safe
high speed until the temperature
gauge stops rising and remains
stationary; in other words, until
the engine reaches a constant
operating temperature.
4. Without changing engine speed,
put the free end of rubber hose
into a bottle of water, avoiding
kinks or low bends that might
block the flow of air.
5. Watch for air bubbles in water
bottle. A continuous flow of bub-
bles indicates that air is being
sucked into the cooling system,
or exhaust gas is leaking into the
cooling system past the cylinder
head gasket.
b. Overheating of Cooling
System
It must be remembered that the
Buick pressure system operates
at higher temperatures than sys-
tems operating at atmospheric
pressure. Depending on the pres-
sure in c o o l i n g system, the
temperature of water or perma-
nent t y p e anti-freeze may go
considerably above 212°F without
danger of boiling.
In cases of actual overheating the
following conditions s h o u l d be
checked:
1. Excessive water loss (sub-
par, b, above).
2. Slipping or broken fan belt
(par. 2-22).
3. R a d i a t o r thermostat stuck
(par. 2-23), radiator air passages
clogged, restriction in radiator
core, h o s e s , or water jacket
passages.
4. Improper i g n i t i o n t i m i n g
(par. 10-41).
5. Improper carburetor adjust-
ment (par. 3-8).
6. Exhaust manifold valve stuck
(par. 3-7).
7. Shortage of engine oil or im-
proper lubrication due to internal
conditions.
8. Dragging brakes.