Air Injection Manifolds; Diverter Test; Check Valve Test - Jeep 1979 CJ-5 Technical & Service Manual

1K-12 EXHAUST SYSTEMS
This moves the metering valve down against its upper
seat and away from its lower seat, diverting air pump
output pressure to atmosphere (fig. 1K-15). Air pump
output is diverted only momentarily because of a bleed
hole in the diaphragm. This hole allows vacuum to
quickly equalize on both sides of the diaphragm and the
diaphragm spring returns the metering valve to its nor-
mal position.
If the air pump develops excessive output pressure,
this excesive pressure overcomes the diaphragm spring
tension, pushing the metering valve down. Pump output
pressure is diverted to atmosphere. When pump output
pressure returns to normal, the metering valve moves
up from the upper seat and against the lower seat,
returning to its normal open position. Pump output
pressure is directed to the exhaust manifold(s).
D I A P H R A G M D I A P H R A G M
PRESSURE
RELIEF O U T L E T
( M E T E R I N G
V A L V E IN
BYPASS
POSITION) A 5 Q 2 7 7
Fig. 1K-15 Diverter Valve—Typical
Oiwerter Test
(1) Start engine and run at idle.
(2) Check diverter vents. Little or no air should flow
from vents.
(3) Accelerate engine to 2000 to 3000 rpm and rap-
idly close throttle. A strong flow of air should pass from
the diverter vents for approximately 5 seconds. The high
flow diverter used on some engines should vent for ap-
proximately 3 seconds. If air does not flow or if backfire
occurs, make certain vacuum sensing line has vacuum
and is not leaking.
N O T E : The diverter valve diverts air pump output
when a vacuum of 20 inches Hg or more is applied at
vacuum sensing line. Diverter also operates when pump
output exceeds 5 psi (8 psi on some models).
(4) Slowly accelerate engine. Between 2500 and 3500
rpm air should begin to flow from diverter vents.
Diverter Replacement
The diverter valve is not serviceable and must be
replaced if defective. The valve is attached to a bracket
or suspended by the hoses between the air pump and air
injection manifolds. Removal involves disconnecting the
hoses, the vacuum sensing line and bracket clamp, if
used. Installation entails connecting the hoses, vacuum
line and bracket clamp, if used.
AIR INJECTION MANIFOLDS
The air injection manifold is constructed of cold-rolled
steel with a zinc plating and distributes air from the
pump to each of the injection screws.
A check valve, incorporating a stainless steel spring
plunger and an asbestos seat, is integral with the air
injection manifold. Its function is to prevent the reverse
flow of exhaust gases to the pump during pump or belt
failure or diverter valve bypass operation. Reverse flow
would damage the air pump and connecting hoses.
The distribution tubes of the air injection manifold
are connected directly to the exhaust manifold. The hol-
low attaching screws conduct airflow into the manifold.
Cheek Valve Test
To check the air injection manifold check valve for
proper operation, disconnect the air supply hose at the
injection manifold. With the engine running above idle
speed, listen and feel for exhaust leakage at the check
valve. A slight leak is normal.
Removal—Six-Cylinior Engine
(1) Disconnect air delivery hose at check valve.
(2) Remove injection screws from each cylinder ex-
haust port.
N O T E : Some resistance to removal may be encoun-
tered due to carbon build-up on the screws.
(3) Remove air injection manifold.