1999 DODGE RAM radiator cap

GEN ER AL C O OLIN G S YSTE M S ER VIC IN G
1999 D odge P ic ku p R 1500
GENERAL INFORMATION
General Cooling System Servicing
* PLEASE READ THIS FIRST *
The following article is for general information only.
Information may not apply to all years, makes and models. See specific
article in the ENGINE COOLING section.
DESCRIPTION
The basic liquid cooling system consists of a radiator, water
pump, thermostat, electric or belt-driven cooling fan, pressure cap,
heater, and various connecting hoses and cooling passages in the block
and cylinder head.
MAINTENANCE
DRAINING
Remove radiator cap and open heater control valve to maximum
heat position. Open drain cocks or remove plugs in bottom of radiator
and engine block. In-line engines usually have one plug or drain cock,
while "V" type engines will have 2, one in each bank of cylinders.
CLEANING
A good cleaning compound removes most rust and scale. Follow
manufacturer's instructions in the use of cleaner. If considerable
rust and scale has to be removed, cooling system should be flushed.
Clean radiator air passages with compressed air.
FLUSHING
CAUTION: Some manufacturers use an aluminum and plastic radiator.
Flushing solution must be compatible with aluminum.
Back Flushing
Back flushing is an effective means of removing cooling
system rust and scale. The radiator, engine and heater core should be
flushed separately.
Radiator
To flush radiator, connect flushing gun to water outlet of
radiator and disconnect water inlet hose. To prevent flooding engine,
use a hose connected to radiator inlet. Use air in short bursts to
prevent damage to radiator. Continue flushing until water runs clear.
Engine
To flush engine, remove thermostat and replace housing.
Connect flushing gun to water outlet of engine. Flush using short air
bursts until water runs clean.
Heater Core
Flush heater core as described for radiator. Ensure heater
control valve is set to maximum heat position before flushing heater.

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.

CAUTION: If fuel contamination due to fungi or other microorganisms is
suspected a fuel additive with a biocide may be used. Follow
the manufacturers dosage as recommended on product label. Use
biocides ONLY when necessary, excessive use can may cause
other fuel system problems.
DIESEL FUEL CONTAMINATION
WARNING: Diesel fuel system may be contaminated with fungi or other
microorganisms. Keep contaminated fuel away from open skin
cuts or sores to prevent skin irritation or infection.
DIESEL FUEL REQUIREMENTS
CAUTION: All diesel engines have been developed to take advantage of
the high energy content of No. 2 diesel fuel or No. 2
climatized-diesel fuels. It also operates on No. 1-diesel
fuels if temperatures are expected to be extended arctic
conditions -10
\bF (-23\bC).
WARNING: Do NOT use alcohol or gasoline as a fuel blending agent. They
can be unstable under certain conditions and hazardous or
explosive when mixed with diesel fuel.
ELECTROSTATIC DISCHARGE SENSITIVE (ESD) PARTS
WARNING: Many solid state electrical components can be damaged by
static electricity (ESD). Some will display a warning label,
but many will not. Discharge personal static electricity by
touching a metal ground point on the vehicle prior to
servicing any ESD sensitive component.
ENGINE OIL
CAUTION: Never use non-detergent or straight mineral oil.
ENGINE OIL FILTER (CARTRIDGE TYPE)
CAUTION: Use of Mopar Oil Filter Cartridge (P/N 04746914) is
RECOMMENDED. The engine oil filter cartridge should be
changed at every engine oil change. Use the same type oil
that will be used in the engine.
FUEL SYSTEM SERVICE
WARNING: Relieve fuel system pressure prior to servicing any fuel
system component (fuel injection models).
HALOGEN BULBS
WARNING: Halogen bulbs contain pressurized gas which may explode if
overheated. DO NOT touch glass portion of bulb with bare
hands. Eye protection should be worn when handling or working
around halogen bulbs.
RADIATOR CAP
CAUTION: Always disconnect the fan motor when working near the
radiator fan. The fan is temperature controlled and could
start at any time even when the ignition key is in the OFF
position. DO NOT loosen or remove radiator cap when cooling
system is hot.

article.
POSITIVE CRANKCASE VENTILATION (PCV)
PCV Valve
1) With engine running at curb idle, remove PCV valve from
grommet. If valve is functioning properly, a hissing sound will be
heard as air passes through valve.
2) With engine running, place finger over valve inlet. Strong
vacuum should be felt at valve inlet. Stop engine. Remove and shake
PCV valve to ensure a metallic clicking noise can be heard, indicating
valve is free. Reinstall PCV valve.
3) Remove crankcase ventilation filter or oil filler cap from
valve cover. Hold a piece of stiff paper over opening. After allowing
about one minute for crankcase pressure stabilization, paper should be
drawn against opening.
4) If paper is held against opening, performance is okay. If
paper is not held against opening, replace PCV valve and retest. If
performance does not improve, inspect system for restrictions and
clean as necessary.
MISCELLANEOUS CONTROLS
NOTE: Although the controlled devices listed here are not
technically engine performance components, they can affect
driveability if they malfunction.
RELAYS
A/C Clutch Relay
See A/C CLUTCH RELAY under RELAYS.
Radiator Fan Control Relay
See RADIATOR FAN CONTROL RELAY under RELAYS.
Torque Converter Clutch (TCC) Relay
See TORQUE CONVERTER CLUTCH (TCC) RELAY under RELAYS
Transmission Governor Pressure Solenoid Relay
See TRANSMISSION GOVERNOR PRESSURE SOLENOID RELAY under
RELAYS.
Transmission 12-Volt Supply Relay
See TRANSMISSION 12-VOLT SUPPLY RELAY under RELAYS.
Vehicle Speed Control Relay
See VEHICLE SPEED CONTROL RELAY under RELAYS.