1999 DODGE RAM gas type

be detected if leak testing is performed too quickly.
BUBBLE DETECTOR LEAK TESTING PROCEDURE
This leak detection method is recommended when it is
impossible or difficult to determine the exact location of the leak
using other methods. Although commercial bubble detectors are more
effective, household soap solutions may be used.
Using the dauber that comes with the commercial soap
solution, apply the solution to all joints, connections, fittings or
controls where a leak might be suspected. If high-suds household
solutions are used, apply them with a small brush. Wherever bubbles
form, leaks are present and must be repaired. check the entire system
as there may be more than one leak.
ELECTRONIC LEAK TESTING PROCEDURE
NOTE: Some electronic leak detectors will function on only R-12
systems or on only R-134a systems, and some will function on
both R-12 and R-134a systems. Familiarize yourself with the
tester being used and know what type of system you are leak
testing.
Electronic leak detectors should be used in well ventilated
areas. Avoid using them around explosive gases. Always follow
manufacturer's instructions for the specific tester being used. If
none are available, proceed as follows:
1) Turn all controls and detector sensitivity knob to OFF
position or zero setting. Connect leak detector to an approved source
of power. Turn switch ON, and allow unit to warm up for approximately
5 minutes.
2) Check operation of tester by positioning probe in a
reference source where refrigerant is known to be present in small
amounts. Adjust controls and sensitivity knob until detector reacts
properly. Move probe away from refrigerant source and the reaction
should stop. If it continues, adjust the sensitivity knob to a lower
setting.
3) When tester reacts properly, leak test air conditioning
system by moving probe UNDER all components, fittings and connections.
Keep the probe moving. To check evaporator insert probe into drain
tube opening or a heater duct. DO NOT allow probe to contact
refrigerant or refrigerant oil. When leaks are found, repair them as
necessary. Keep in mind that there may be more than one leak.
DYE SOLUTION LEAK TESTING PROCEDURES
CAUTION: Dye-charged refrigerant cans are available to be used as
internal leak detectors. The use of this type of solution may
void some manufacturer's warranties. Be sure to check with
the A/C system manufacturer concerning the use of dye-charged
leak detectors. Dyes which work in R-12 systems will not work
in R-134a systems.
The following procedure is for introducing a dye solution,
not dye-charged refrigerant, into A/C system.
1) Connect manifold gauge set to air conditioning system in a
normal manner. Remove center hose from manifold gauge set, and replace
it with a short piece (6" long) of 1/4" tubing using two 1/4" flare
nuts. Connect a container of dye solution to the tubing.
2) Connect one end of gauge set center hose to dye solution
container. Connect a container of refrigerant to the other end of the
hose. Operate engine at idle speed. Set the air conditioning system
for maximum cooling. Slowly open the low-side hand valve to allow the

NOTE: Electro-magnetic interference (EMI) may be caused by
incorrect installation of accessories or components. EMI can
result in improper system operation.
BACKING PLATES
BACKING PLATE INSPECTION








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Condition Code Procedure
Anchor pin bent ......... B .. Require repair or replacement.
Anchor pin broken ....... A ............ Require replacement.
Anchor pin worn, affecting
structural integrity ... B ............ Require replacement.
Backing plate bent ...... B .. Require repair or replacement.
Backing plate broken .... A ............ Require replacement.
Backing plate cracked ... B .. Require repair or replacement.
Corroded, affecting
structural integrity .... A ............ Require replacement.
Loose ................... B .. Require repair or replacement.
Missing ................. C ............ Require replacement.
Shoe lands worn ......... A .. Require repair or replacement.









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BRAKE FLUID
CAUTION: Most manufacturers prohibit the use of DOT 5 brake fluid
in a system equipped with ABS.
DOT 3, DOT 4, and DOT 5.1 brake fluids are clear or light
amber in color. DOT 5 brake fluid is violet in color. Correct fluid
required for the brake system is stamped on the master cylinder cover.
BRAKE FLUID INSPECTION









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Condition Code Procedure
Beyond service interval . 3 .. Suggest flushing and refilling
with correct fluid.
Brake fluid type
incorrect .............. B .. Require flushing and refilling
with correct fluid.
Contaminated, for example,
fluid other than brake
fluid present .......... A or B ....... ( 1) Require service.
Hydraulic component ..... 3 .. Suggest flushing and refilling
overhaul or replacement with correct fluid.
Rubber master cylinder
cover gasket distorted
and gummy .............. A .......... ( 2) Require replacement
of gasket.
( 1) - If a fluid other than brake fluid is present in the brake
system which DOES affect the rubber parts, the required
service is to:
* Remove all components having rubber parts from the
system.
* Flush lines with denatured alcohol or brake cleaner
* Repair or replace all components having rubber parts
* Flush and fill with correct brake fluid. (Code A)
If a fluid other than brake fluid is present in the brake

FLUID TYPE
Use SAE 80W-90 or 90W hypoid gear lubricant with MIL-L-2105-C
and API GL-5 ratings.
TROUBLE SHOOTING
NOTE: See appropriate table in TROUBLE SHOOTING article in GENERAL
INFORMATION.
REMOVAL & INSTALLATION
AXLE SHAFT & HUB BEARING
Removal
1) Raise and support vehicle. Remove wheel. Remove brake
caliper with hose attached, and secure aside. DO NOT allow brake
caliper to hang by brake hose. Remove brake rotor. Remove ABS wheel
speed sensor (if equipped). Remove grease cap from center of front
hub. Remove cotter pin from end of axle shaft. Remove axle nut and
washer.
2) Remove hub/bearing assembly-to-knuckle bolts. Remove
hub/bearing assembly from steering knuckle and axle shaft. Remove
brake dust shield. To remove right (passenger-side) axle shaft,
carefully pull axle shaft from axle housing.
NOTE: Left axle shaft will disengage from collar located on
intermediate axle shaft.
3) To remove left (driver's side) axle shaft, disconnect
electrical connector and vacuum hoses at vacuum shift motor. Remove
bolts, vacuum shift motor and gasket. Carefully pull axle shaft from
axle housing and collar on intermediate axle shaft.
Installation
1) Install NEW oil seal on axle shaft with seal lip facing
toward splines on differential end of axle shaft. Coat seal lip with
wheel bearing grease.
2) Install right axle shaft into axle housing. Ensure axle
shaft engages with side gears in differential.
3) To install left axle shaft, ensure collar is engaged with
splines on intermediate axle shaft. Install left axle shaft into axle
housing. Ensure axle shaft engages with splines on collar. Install
vacuum shift motor, ensuring fork on vacuum shift motor engages groove
on collar. Install and tighten bolts to specification. See TORQUE
SPECIFICATIONS table.
4) To complete installation, reverse removal procedure. Apply
silicone rubber sealant to edge of grease cap before installing.
Tighten bolts/nuts to specification. See TORQUE SPECIFICATIONS table.
DRIVE SHAFT
Removal
1) Raise and support vehicle. Ensure transmission and
transfer selector levers case are in Neutral. Reference mark drive
shaft and pinion flange for reassembly reference.
2) Remove bolts and "U" joint straps at pinion flange. Remove
center carrier bearing bolts (if equipped). Remove drive shaft.
CAUTION: The "U" joint components are not serviceable. Replace
complete assembly. DO NOT reuse.

267 RBI ................................................ 7.0 (3.3)\
286 RBI
2WD ................................................... 6.8 (3.2)\
4WD .................................................. 10.1 (4.8)\
Ram Van/Wagon
248 RBI ................................................ 6.0 (2.8)\
(1) - Approximate drive axle capacity listed. Lubricant level should
be 1/2" below oil filler hole in axle housing cover.









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FLUID TYPE
Use SAE 80W-90 for 286 models, or 90W for all other models,
hypoid gear lubricant with MIL-L-2105-C and API GL-5 ratings. Models
with Trac-Lok require addition of 6 ozs. (.18 L) Mopar(R) friction
modifier (limited slip additive). Ram Pickups equipped with Power-Lok
require addition of 8 ozs. (.24 L) Mopar(R) friction modifier.
TROUBLE SHOOTING
NOTE: See appropriate table in TROUBLE SHOOTING article in GENERAL
INFORMATION.
REMOVAL & INSTALLATION
REAR HUB, BEARINGS & AXLE SHAFT
Removal
Raise and support vehicle. Remove wheel. Remove bolts, axle
shaft and gasket. Remove nut lock from adjusting nut. See Fig. 1.
Remove adjusting nut and outer wheel bearing. Remove rear hub and
brake drum. Remove oil seal and inner wheel bearing (if necessary).
Installation
1) Pack wheel bearings with wheel bearing grease. Install
inner wheel bearing and oil seal in rear hub (if removed). Install
rear hub and brake drum. Install outer wheel bearing and adjusting
nut. Tighten adjusting nut to specification while rotating rear hub
and brake drum. See TORQUE SPECIFICATIONS table.
2) Back off adjusting nut approximately 1/8 turn to obtain .
001-.010" (.03-.25 mm) wheel bearing end play. Tap key lock into
adjusting nut and keyway on axle housing.
3) To install remaining components, reverse removal
procedure. Use NEW gasket when installing axle shaft. Tighten bolts to
specification. See TORQUE SPECIFICATIONS table.
DRIVE SHAFT
Removal
1) Raise and support vehicle. Ensure transmission and
transfer case selector levers are in Neutral. Remove wheel assembly.
Remove RWAL sensor, if equipped. Reference mark drive shaft to pinion
flange for reassembly.
2) On 2-piece drive shafts, scribe center carrier bearing-to-
frame bracket reference line for reassembly. On all drive shafts,
remove bolts and "U" joint straps at pinion flange. Remove center
carrier bearing bolts, if equipped. Remove spring clamps and brackets.
Remove drive shaft(s).
CAUTION: The "U" joint straps and bolts must be replaced. DO NOT

inspection procedures.
A visual inspection is made to determine if any required
emission control devices are missing, modified or disconnected.
Missing, modified or disconnected systems must be made fully
operational before a vehicle can be certified.
POSITIVE CRANKCASE VENTILATION (PCV)
PCV controls the flow of crankcase fumes into the intake
manifold while preventing gases and flames from traveling in the
opposite direction. PCV is either an open or closed system. See Fig. 2
.
Ensure PCV system is installed as required. Verify valve,
required hoses, connections, flame arresters, etc., are present,
routed properly and in serviceable condition.
Fig. 2: Typical Open & Closed Type PCV System
THERMOSTATIC AIR CLEANER (TAC)
The TAC supplies warm air to air intake during cold engine
operation. This system is active during cold engine warm-up only.
Under all other operating conditions, air cleaner function is the same
as any non-thermostatic unit.
Ensure required exhaust shroud, hot air duct, vacuum hoses
and air cleaner components are present and installed properly. See
Fig. 3 . Ensure any required thermostatic vacuum switches are in place
and vacuum hoses are installed and in serviceable condition. Also
ensure air cleaner lid is installed right side up. Check for oversized
air filter elements and for additional holes in the air cleaner
housing.

Single Diaphragm EGR Valve
This type uses a single diaphragm connected to the valve by a
shaft. Diaphragm is spring-loaded to keep valve closed in the absence
of vacuum. As throttle valves open and engine speed increases, vacuum
is applied to the EGR vacuum diaphragm, opening the EGR valve. This
vacuum signal comes from a ported vacuum source. Variations in the
vacuum signal control the amount of exhaust gas that is recirculated.
See Fig. 7 .
Verify EGR valve is present and not modified or purposely
damaged. Ensure thermal vacuum switches, pressure transducers, speed
switches, etc., (if applicable) are not by-passed or modified. Ensure
vacuum hose(s) to EGR valve is not plugged.
Fig. 7: Typical Single Diaphragm EGR Valve
Courtesy of General Motors Corp.
Dual Diaphragm EGR Valve
This type uses 2 diaphragms with different effective areas
and 2 vacuum sources. Although similar to the single diaphragm type,
the second diaphragm is added below the upper diaphragm and is rigidly
attached to the valve seat. See Fig. 8. These diaphragms form a vacuum
chamber which is connected to manifold vacuum.
During highway cruising when manifold vacuum is high in the
center chamber, manifold vacuum tends to pull the valve closed.
However, the vacuum signal applied to the top side of the upper
diaphragm overcomes the downward spring force and the manifold vacuum
pull, due to the diaphragm's larger piston. This regulates the amount
of EGR.
When manifold vacuum is low during acceleration, the higher
vacuum signal opens the valve, permitting more EGR. When manifold
vacuum is high during highway cruising, the valve is only partially
opened, reducing the amount of EGR.

These 3 orifices are opened and closed by electric solenoids. The
solenoids are, in turn, controlled by the Electronic Control Module
(ECM). When a solenoid is energized, the armature with attached shaft
and swivel pintle is lifted, opening the orifice. See Fig. 11.
The ECM uses inputs from the Coolant Temperature Sensor
(CTS), Throttle Position Sensor (TPS) and Mass Airflow (MAF) senso\
rs
to control the EGR orifices to make 7 different combinations for
precise EGR flow control. At idle, the EGR valve allows a very small
amount of exhaust gas to enter the intake manifold. This EGR valve
normally operates above idle speed during warm engine operation.
Verify EGR valve is present and not modified or purposely
damaged. Ensure thermal vacuum switches, pressure transducers, speed
switches, etc., (if applicable) are not by-passed or modified. Ensure
vacuum hose(s) to EGR valve is not plugged. Ensure electrical
connector to EGR valve is not disconnected.
Fig. 11: Typical Digital EGR Valve
Courtesy of General Motors Corp.
Integrated Electronic EGR Valve
This type functions similar to a ported EGR valve with a

Spark control systems are designed to ensure the air/fuel
mixture is ignited at the best possible moment to provide optimum
efficiency and power and cleaner emissions.
Ensure vacuum hoses to the distributor, carburetor, spark
delay valves, thermal vacuum switches, etc., are in place and routed
properly. On Computerized Engine Controls (CEC), check for presence of\
required sensors (O2, MAP, CTS, TPS, etc.). Ensure they have not been
tampered with or modified.
Check for visible modification or replacement of the feedback
carburetor, fuel injection unit or injector(s) with a non-feedback
carburetor or fuel injection system. Check for modified emission-
related components unacceptable for use on pollution-controlled
vehicles.
AIR INJECTION SYSTEM (AIS)
Air Pump Injection System (AP)
The air pump is a belt-driven vane type pump, mounted to
engine in combination with other accessories. The air pump itself
consists of the pump housing, an inner air cavity, a rotor and a vane
assembly. As the vanes turn in the housing, filtered air is drawn in
through the intake port and pushed out through the exhaust port. See
Fig. 13 .
Check for missing or disconnected belt, check valve(s),
diverter valve(s), air distribution manifolds, etc. Check air
injection system for proper hose routing.
Fig. 13: Typical Air Pump Injection System
Courtesy of General Motors Corp.
Pulsed Secondary Air Injection (PAIR) System
PAIR eliminates the need for an air pump and most of the
associated hardware. Most systems consists of air delivery pipe(s),
pulse valve(s) and check valve(s). The check valve prevents exhaust
gases from entering the air injection system. See Fig. 14.
Ensure required check valve(s), diverter valve(s), air
distribution manifolds, etc., are present. Check air injection system
for proper hose routing.