Radiator Pressure Cap - Jeep KJ 2005 Service Manual

KJ
RADIATOR (Continued)
INSTALLATION
2.4L ENGINE
CAUTION: Before installing the radiator or A/C con-
denser, be sure the radiator-to-body and radiator-to-
A/C condenser rubber air seals are properly
fastened to their original positions. These are used
at the top, bottom and sides of the radiator and A/C
condenser. To prevent overheating, these seals
must be installed to their original positions.
(1) Gently lower the radiator and fan shroud into
the vehicle. Guide the two radiator alignment dowels
into the rubber grommets located in lower radiator
crossmember.
(2) Connect the radiator upper and lower hoses
and hose clamps to radiator.
CAUTION: The tangs on the hose clamps must be
positioned straight down.
(3) Install coolant reserve/overflow tank hose at
radiator.
(4) Install both radiator mounting bolts.
(5) Reconnect the electric cooling fan.
(6) Install the grill (Refer to 23 - BODY/EXTERI-
OR/GRILLE - INSTALLATION).
(7) Reinstall the cooling fan to the engine.
(8) Rotate the fan blades (by hand) and check for
interference at fan shroud.
(9) Refill cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
(10) Connect battery cable at battery.
(11) Start and warm engine. Check for leaks.

RADIATOR PRESSURE CAP

DESCRIPTION
The cooling system cap is located on the coolant
pressure bottle for 3.7L/2.8L Diesel engine and the
radiator for the 2.4L engine. The cap construction
includes; stainless steel swivel top, rubber seals and
retainer, main spring, and a spring loaded valve (Fig.
18).
OPERATION
The pressure cap allows the cooling system to oper-
ate at higher than atmospheric pressure which raises
the coolant boiling point, thus allowing increased
radiator cooling capacity. The pressure cap releases
pressure at some point within a range of 110 kPa ±
14 kPa (16 psi ± 2 psi).
A spring-loaded vent valve in the center of the cap
allows the system to pressurize and depressurize
without creating a vacuum. If the valve is stuck
Fig. 18 PRESSURE CAP
1 - MAIN SPRING
2 - GASKET RETAINER
3 - STAINLESS STEEL SWIVEL TOP
4 - RUBBER SEALS
5 - SPRING LOADED VALVE
6 - COOLANT PRESSURE BOTTLE
7 - FILLER NECK
8 - OVERFLOW NIPPLE
open, coolant will escape to the overflow hose. There
is also a gasket in the cap to seal to the top of the
filler neck.
CAUTION: Use only the pressure cap specified for
this vehicle. Use of other pressure caps can lead to
coolant loss and overheating.
DIAGNOSIS AND TESTING
RADIATOR PRESSURE CAP - GAS ENGINES
Remove cap from pressure bottle or radiator as
appropriate. Be sure that sealing surfaces are clean.
Moisten rubber gasket with water and install the cap
on pressure tester (tool 7700 or an equivalent) (Fig.
19).
Operate the tester pump and observe the gauge
pointer at its highest point. The cap release pressure
should be 124 to 145 kPa (18 to 21 psi). The cap is
satisfactory when the pressure holds steady. It is also
good if it holds pressure within the 124 to 145 kPa
(18 to 21 psi) range for 30 seconds or more. If the
pointer drops quickly, replace the cap.
CAUTION: Radiator pressure testing tools are very
sensitive to small air leaks, which will not cause
cooling system problems. A pressure cap that does
not have a history of coolant loss should not be
replaced just because it leaks slowly when tested
with this tool. Add water to tool. Turn tool upside
down and recheck pressure cap to confirm that cap
needs replacement.
ENGINE 7 - 35