Section 05: COOLING SYSTEM
PA1553
5
NOTE
In order to ensure the integrity of the system,
it is recommended that a periodic cooling
system pressure check be made. Pressurize
the cooling system to 103-138 kPa (15-20 psi)
using Radiator and Cooling System Tester,
J24460-1. Do not exceed 138 kPa (20 psi).
Any measurable drop in pressure may
indicate a leak. Whenever the oil pan is
removed, the cooling system should be
pressure checked as a means of identifying
any incipient coolant leaks. Make sure the
cause of the internal leak has been corrected
before flushing the contaminated system.
Leaks at the thermostat housing hose
connections may be caused by deformation of
connections or by rough surfaces on the castings
of the hose mounting surfaces. It is
recommended that "Dow Corning RTV-102
Compound" or any equivalent product be applied
on cast surfaces prior to hose installation.
CAUTION
Castings should be clean and free of oil and
grease before applying compound. No other
sealer should be used with RTV-102
compound.
3. HOSES
Rotten, swollen, and worn out hoses or loose
connections are frequent causes of cooling
system problems.
Serious overheating is often caused by an old
hose collapsing or from rotten rubber shedding
from hoses and clogging the coolant passages.
Connections should be inspected periodically
and hose clamps tightened. Replace any hose
found to be cracked or swollen.
When installing a new hose, clean pipe
connections and apply a thin layer of a
non-hardening sealing compound. Replace worn
out clamps or clamps that pinch hoses.
3.1 CONSTANT-TORQUE HOSE CLAMPS
All hose clamps of 1 3/8" ID and over, used on
the heating and cooling systems, are of the
"Constant-torque" type. These clamps are
worm-driven, made of stainless steel, and
supplied with a series of Belleville spring
washers. They also feature an extended integral
liner that covers the band slots to protect
soft/silicone hoses from damage, and help
maintain consistent sealing pressure.
This type of clamp is designed to automatically
adjust its diameter to compensate for the normal
expansion/contraction of a hose and metal
connection that occurs during vehicle operation
and shutdown. The constant-torque clamp
virtually eliminates coolant losses due to "Cold
flow" leakage and greatly minimizes clamp
maintenance.
3.1.1 Installation
A torque wrench should be used for proper
installation. The recommended torque is 90 to
100 lbf-in. (10 to 11 Nm). The Belleville spring
washer stacks should be nearly collapsed flat
and the screw tip should extend ¼" (6 mm)
beyond the housing (Fig. 3).
FIGURE 3: CONSTANT-TORQUE CLAMP 05037
CAUTION
The hose clamps will break if over-torqued.
Do not over-tighten, especially during cold
weather when hose has contracted.
3.1.2 Maintenance
The constant-torque clamps contain a "Visual
torque check“ feature. When the tip of the screw
is extending ¼" (6 mm) out of the housing, the
clamp is properly installed and maintains a
leak-proof connection. Since the constant-torque
clamp automatically adjusts to keep a consistent
sealing pressure, there is no need to re-torque
hose clamps on a regular basis. During vehicle
operation and shutdown, the screw tip will adjust
according to the temperature and pressure
changes. Checking for proper torque should
be done at room temperature.
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