Cooling System Check; Underhood Hose Check And Replacement; Vacuum Hoses; Fuel Hoses - Jeep cherokee 1989 Owner's Manual

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9 Cooling system check

Refer to illustration 9.4
Many major engine failures can be attributed t o a faulty cooling
1
system. If the vehicle is equipped with an automatic transmission, the
cooling system also cools the transmission fluid and thus plays an im-
portant role in prolonging transmission life.
2 The cooling system should be checked with the engine cold. Do
this before the vehicle is driven for the day or after it has been shut
off for at least three hours.
3 On four-cylinder and V6 engines, remove the radiator cap by turning
it to the left until it reaches a stop. If you hear a hissing sound (in-
dicating there is still pressure in the system), wait until this stops. Now
press down on the cap with the palm of your hand and continue turning
t o the left until the cap can be pulled off. Thoroughly clean the cap,
inside and out, with clean water. Also clean the filler neck on the
radiator. All traces of corrosion should be removed. On inline six-
cylinder engines, unscrew the cap on the coolant pressure bottle and
clean the cap. The coolant inside the radiator or pressure bottle should
be relatively transparent. If it is rust colored, the system should be
drained and refilled (Section 39). If the coolant level is not up to the
top, add additional antifreezelcoolant mixture (see Section 4).
4 Carefully check the large upper and lower radiator hoses along with
the smaller diameter heater hoses which run from the engine to the
firewall. On some models the heater return hose runs directly to the
radiator. On inline six-cylinder vehicles, also inspect the hoses attached
to the coolant pressure bottle. lnspect each hose along its entire length,
replacing any hose which is cracked, swollen or shows signs of
deterioration. Cracks may become more apparent if the hose is
squeezed (see illustration). Regardless of condition, it's a good idea
to replace hoses with new ones every t w o years.
5 Make sure that all hose connections are tight. A leak in the cooling
svstem will usually show up as white or rust colored deposits on the
A L W A Y S C H E C K hose for chafed
or burned areas that may cause an
SOFT
clog the radlator
H A R D E N E D hose can fall at any tlme
SWOLLEN
the hose t o locate cracks and breaks
\
that cause leaks
9.4 Hoses, like drivebelts. have a habit of failing at the
-
worst possible time t o prevent the inconvenience
of a blown radiator or heater hose, inspect them
carefully as shown here
The Motor Manual Guy
Chapter 1 Tune-up and routine maintenance
hose mdtcates m l d e deterloratton
hose or soaked ends In
or grease contammation. Squeeze
areas adjoining the leak. If wire-type clamps are used at the ends of
the hoses, it may be a good idea to replace them with more secure
screw-type clamps.
6 Use compressed air or a soft brush t o remove bugs, leaves, etc.
from the front of the radiator or air conditioning condenser. Be careful
not to damage the delicate cooling fins or cut yourself on them.
7 Every other inspection, or at the first indication of cooling system
problems, have the cap and system pressure tested. If you don't have
a pressure tester, most gas stations and repair shops will do this for
a minimal charge.

10 Underhood hose check and replacement

General
1 Caution: Replacement o f air conditioning hoses must be left to a
dealer service department or air conditioning shop that has the e q u i p
ment to depressurize the system safely. Never remove air conditioning
components or hoses until the system has been depressurized.
2 High temperatures in the engine compartment can cause the deter-
ioration of the rubber and plastic hoses used for engine, accessory and
emission systems operation. Periodic inspection should be made for
cracks, loose clamps, material hardening and leaks. Information specific
to the cooling system hoses can be found in Section 9.
3 Some, but not all, hoses are secured to the fittings with clamps.
Where clamps are used, check to be sure they haven't lost their tension,
allowing the hose t o leak. If clamps aren't used, make sure the hose
has not expanded andlor hardened where it slips over the fitting, allow-
ing it t o leak.

Vacuum hoses

4 It's quite common for vacuum hoses, especially those in the emis-
sions system, to be color coded or identified by colored stripes molded
into them. Various systems require hoses with different wall thick-
nesses, collapse resistance and temperature resistance. When replacing
hoses, be sure the new ones are made of the same material.
5 Often the only effective way to check a hose is to remove it com-
pletely from the vehicle. If more than one hose is removed, be sure
to label the hoses and fittings t o ensure correct installation.
6 When checking vacuum hoses, be sure to include any plastic T-
fittings in the check. lnspect the fittings for cracks and the hose where
it fits over the fitting for distortion, which could cause leakage.
7 A small piece of vacuum hose (114-inch inside diameter) can be
used as a stethoscope t o detect vacuum leaks. Hold one end of the
hose t o your ear and probe around vacuum hoses and fittings, listen-
ing for the "hissing" sound characteristic of a vacuum leak. Warning:
When probing with the vacuum hose stethoscope, be very careful n o t
to come into contact with moving engine components such as the drive-
belt, cooling fan, etc.

Fuel hoses

Warning: There are certain precautions which must be taken when in-
specting or servicing fuel system components. Work in a well ventilated
area and do n o t allow open flames (cigarettes, appliance pilot lights,
mediately and do n o t store fuel soaked rags where they could ignite.
On vehicles equipped with fuel injection, the fuel system is under
pressure, so i f any fuel lines are to be disconnected, the pressure in
the system must be relieved first (see Chapter 4 for more information).
8 Check all rubber fuel lines for deterioration and chafing. Check
especially for cracks in areas where the hose bends and just before
fittings, such as where a hose attaches to the fuel filter.
9 High quality fuel line, usually identified by the word Fluroelastomer
printed on the hose, should be used for fuel line replacement. Never,
under any circumstances, use unreinforced vacuum line, clear plastic
tubing or water hose for fuel lines.
10 Spring-type clamps are commonly used on fuel lines. These clamps
often lose their tension over a period of time, and can be "sprung"
during removal. Replace all spring-type clamps with screw clamps
whenever a hose is replaced.
Metal lines
1 1 Sections of metal line are often used for fuel line between the fuel
pump and carburetor or fuel injection unit. Check carefully t o be sure