Chrysler DODGE D150 1993 Service Manual page 1493

25 - 16 EMISSION CONTROL SYSTEMS •
DOWNSTREAM
d c i i c c
H O S E RELIEF
H O L E S J9325-37
Fig. 2 Air Injection Pump Operation
cessive noise is fault of air injection system, discon­
nect drive belt and operate engine.
C A U T I O N : Do not lubricate air injection pump. Wipe
all oil off of pump housing. Oil in the pump will
cause rapid deterioration and failure.
C A U T I O N : Completely cover the air pump before
cleaning the engine or underhood compartment.
Refer to the Component Removal/Installation section
of this group for air pump replacement procedures.
CHECK VALVE—AIR INJECTION TUBE
A check valve (Fig. 1) is located on each of the air
injection downstream tubes.
The check valve has a one-way diaphragm which pre­
vents hot exhaust gases from backing up into the hose
and pump. The check valve will protect the system if
the air injection pump belt fails, an air hose ruptures or
exhaust system pressure becomes abnormally high.
TESTING CHECK VALVE
The check valves are not repairable. To determine
condition of valve, remove the rubber air tube from
the inlet side of each check valve. Start the engine. If
exhaust gas is escaping through the inlet side of
valve, it must be replaced.
Refer to the Component Removal/Installation section
of this group for check valve replacement procedures.
AIR PUMP DIAGNOSIS
Condition
Possible Cause
Correction
EXCESSIVE BELT NOISE
(a) Loose belt or defective auto, belt tensioner.
(a) Refer to Group 7, Cooling.
(b) Seized pump.
(b) Replace pump.
EXCESSIVE PUMP NOISE.
CHIRPING
(a) Insufficient break-in.
(a) Recheck for noise after 1600 km.
(1,000 miles) of operation.
EXCESSIVE PUMP NOISE CHIRPING,
RUMBUNG, OR KNOCKING
(a) Leak in hose.
(a) Locate source of leak using soap
solution and correct.
(b) Loose hose.
(b) Reassemble and replace or tighten
hose clamp.
(c) Hose touching other engine parts.
(c) Adjust hose position.
(d) Relief valve inoperative.
(d) Replace relief valve.
(e) Check valve inoperative.
(e) Replace check valve.
(f) Pump mounting fasteners loose.
(f) Tighten mounting screws as specified.
(g) Pump failure.
(g) Replace pump.
N O AIR SUPPLY (ACCELERATE ENGINE TO
1500 RPM AND OBSERVE AIR FLOW FROM
HOSES. IF THE FLOW INCREASES A S THE
RPM'S INCREASE, THE PUMP IS FUNCTION­
ING NORMALLY. IF NOT, CHECK POSSIBLE
CAUSE.
(a) Loose drive belt.
(b) Leaks in supply hose.
(c) Leak at fitting(s).
(a) Refer to Group 7, Cooling.
(b) Locate leak and repair or replace as
required.
(c) Tighten or replace clamps.
(d) Check valve inoperative.
(d) Replace check valve.
J9325-38