Mitsubishi Montero (1991+). Manual — part 151

REFILLING

To prevent air from being trapped in engine block, engine

should be running when refilling cooling system. After system is full,

continue running engine until thermostat is open, then recheck fill

level. Do not overfill system.

TESTING

THERMOSTAT

1) Visually inspect thermostat for corrosion and proper

sealing of valve and seat. If okay, suspend thermostat and thermometer

in a 50/50 mixture of coolant and water. See Fig. 1. Do not allow

thermostat or thermometer to touch bottom of container. Heat water

until thermostat just begins to open.

2) Read temperature on thermometer. This is the initial

opening temperature and should be within specification. Continue

heating water until thermostat is fully open and note temperature.

This is the fully opened temperature. If either reading is not to

specification, replace thermostat.

Fig. 1: Testing Thermostat in Anti-Freeze/Water Solution

PRESSURE TESTING

A pressure tester is used to check both radiator cap and

complete cooling system. Test components as follows, following tool

manufacturer’s instructions.

Radiator Cap

Visually inspect radiator cap, then dip cap into water and

connect to tester. Pump tester to bring pressure to upper limit of cap

specification. If cap fails to hold pressure, replace cap.

Fig. 2: Testing Radiator Pressure Cap

Cooling System

1) With engine off, wipe radiator filler neck seat clean.

Fill radiator to correct level. Attach tester to radiator and pump

until pressure is at upper level of radiator rating.

2) If pressure drops, inspect for external leaks. If no leaks

are apparent, detach tester and run engine until normal operating

temperature is reached. Reattach tester and observe. If pressure

builds up immediately, a possible leak exists from a faulty head

gasket or crack in head or block.

NOTE: Pressure may build up quickly. Release any excess pressure

or cooling system damage may result.

3) If there is no immediate pressure build up, pump tester to

within system pressure range (on radiator cap). Vibration of gauge

pointer indicates compression or combustion leak into cooling system.

Isolate leak by shorting each spark plug wire to cylinder block. Gauge

pointer should stop or decrease vibration when leaking cylinder is

shorted.

HEATER SYSTEM

1991 Mitsubishi Montero

1991-92 HEATER SYSTEMS

Chrysler Motors, Mitsubishi

Chrysler Motors: Ram-50

Mitsubishi: Montero, Pickup

DESCRIPTION

Heater assembly on all models is located in passenger

compartment. A heater control valve is used to regulate coolant flow

and heat output. Heater assembly contains heater core, heater control

valve, air ducts, blower motor and intake ducts. See Fig. 1 or 2.

Heater systems are blend-air type.

Fig. 1: Identifying Heater System Components (Montero)

Courtesy of Mitsubishi Motor Sales of America.

Fig. 2: Identifying Heater System Components (Pickup & Ram-50)

Courtesy of Mitsubishi Motor Sales of America.

OPERATION

Heater and fresh air operations are controlled by knobs on

some models and control levers on others. The control panel of models

equipped with control levers consists of mode control levers for

inside/outside air, temperature control, air selector and multi-speed

blower switch.

The temperature control opens and closes heater control

valve, which determines heat output. Heater mode control directs

heated air to windshield when in DEF position, to floor when in HEAT

position, or to center ventilation ducts when in VENT position. Bi-

level output is possible by positioning lever between VENT and HEAT

positions.

TEMPERATURE CONTROL LEVER

Temperature level is selected by sliding lever left or right.

Highest heat setting is when selector lever is in WARM position. With

temperature lever set at COOL position, ambient air is used for

ventilating.

AIR SELECTOR LEVER

This lever is used to select source of air flow into vehicle.