Internal Leakage Inspection; Combustion Leakage Test; Transmission Fluid Collar Leakage Test; Cooling System Pressure Test - Jeep J-10 Series 1982 Technical & Service Manual

80052
Hg. 1C-15 Cooling System Pressure Test
(c) Drops Quickly: indicates that serious leak
age is occurring. Examine system for serious external
leakage. If no leaks are visible, inspect for internal
leakage.
NOTE: Large radiator holes or fractures should be re
paired by a reputable radiator repair shop.
Internal Leakage Inspection
(1) Remove oil pan drain plug and drain small
amount of engine oil (coolant, being heavier, should
drain first), or operate engine to churn oil, then examine
dipstick for water globules or foam.
(2) Inspect transmission dipstick for water
globules.
(3) Inspect transmission fluid cooler for leakage.
Refer to Transmission Fluid Cooler Leakage Test.
WARNING: Use extreme caution when engine is oper
ating. Do not stand in direct line with fan. Do not put
hands near pulleys, belts or fan. Do not wear loose
clothing.
(4) Operate engine without pressure cap on radiator
until thermostat opens.
(5) Attach Pressure Tester to filler neck. If pressure
builds up quickly, combustion/compression leak exists
as result of faulty cylinder head gasket, or cracked cylin
der head or block. Repair as necessary.
WARNING: Do not allow pressure to exceed 15 psi
(103.U kPa). Turn engine Off To release pressure, rock
tester from side to side. When removing tester, do not
turn tester more than 1/2 turn if system is under
pressure.
(6) If there is no immediate pressure increase,
pump Pressure Tester until indicated pressure is within
system range. Vibration of gauge pointer indicates com
pression or combustion leakage into cooling system.
CAUTION: Do not disconnect spark plug wires while
engine is operating.
COOLING SYSTEMS 1C-23
CAUTION: Do not operate engine with spark plug
shorted for more than a minute, otherwise catalytic
converter may be damaged.
(7) Isolate compression leak by shorting each spark
plug to cylinder block. Gauge pointer should stop or
decrease vibration when spark plug for leaking cylinder
is shorted to cylinder block because of the absence of
combustion pressure.
Combustion Leakage Test (without Pressure Tester)
NOTE: DO NOT WASTE reusable coolant. If solution
is clean and is being drained only to service the cooling
system, drain coolant into a clean containerfor reuse.
WARNING: DO NOT remove cylinder block drain
plugs or loosen radiator draincock with system hot and
under pressure because serious burnsfrom coolant can
occur.
(1) Drain sufficient coolant to allow thermostat re
moval. Refer to Thermostat Replacement
(2) Disconnect water pump drive belt.
(3) Four- and Eight-Cylinder Engine: remove
thermostat housing cover and remove thermostat.
Six-Cylinder Engine: disconnect upper radiator hose
from thermostat housing, remove housing and thermo
stat, and install thermostat housing on cylinder head.
(4) Add coolant to engine to bring level within 1/4
inch (6.3 mm) of top of thermostat housing.
CAUTION: Avoid overheating. Do not operate engine
for an excessive period of time. Opendraincock immedi
ately after test to eliminate boilover.
(5) Start engine and accelerate rapidly to approx
imately 3000 rpm three times while observing coolant. If
any internal engine combustion gases are leaking into
cooling system, bubbles will appear in coolant. If bub
bles do not appear, there are no internal combustion gas
leakage.
Transmission Fluid Cooler Leakage Test
Transmission Fluid cooler leaks can be detected by the
presence of transmission fluid in the coolant. If fluid
appears in the coolant, check the fluid level of the auto
matic transmission. If the fluid level is low, test the
fluid cooler according to the following procedure:
(1) Remove transmission-to-cooler pipes at
radiator.
(2) Plug one cooler fitting.
(3) Remove radiator cap and ensure radiator is
filled with coolant.
(4) Apply shop air pressure (50 to 100 psi [344 to 690
kPa]) to other cooler fitting.