Form 824426
Page Number - 19
1) Apply 10” vacuum
(cold engine)
4) When engine is
warm (coolant
above 125°F)
2) Gauge will read 10”
3) Gauge will
read zero
2) Apply 10” vacuum
When engine is cold,
vacuum reading
should be zero
1) Warm engine
(above 125°F)
3) Gauge must read
source vacuum
RESULTS:
Vacuum when warm
Lower valve okay
No vacuum when warm
Replace PVS
Vacuum Gauge
4-PORT PVS TEST
UPPER VALVE FLOW
LOWER VALVE FLOW
RESULTS:
No vacuum when warm
Upper valve okay
Vacuum when warm
Replace PVS
thermaL-controLLeD vacuum-switchinG vaLves
3) If full vacuum flows through the valve when
heated, it is okay . If there is no vacuum flow or
there is vacuum flow when the coolant is cold,
replace the valve .
Follow this procedure to test the three-port
vacuum-switching valve:
1) Apply 10” Hg of vacuum with your vac uum
pump to the middle port of the valve with a vacuum
gauge at each of the other two ports .
2) Refer to the same color-coded valves and same
temperature specifications as for the two-port valve
above . If the vacu um switches at the specified
temperature, the valve is okay . If there is no
vacuum to the lower port above the specified
temper ature, replace the valve .
The four-port valve must be tested two times, once
at the top two ports and once at the bottom two
ports as shown in the accompanying illustration
(FIGURE 16) .
1) Apply 10” Hg of vacuum with your vac uum
pump to one of the top two ports . The valve should
hold vacuum when above the specified operating
temperature .
2) If flow occurs when the valve is warm, replace it .
3) For the lower two ports, vacuum must pass
through the valve only when the engine is warm;
otherwise, replace the valve .
FIGURE 16: TESTING THE FOUR-PORT PVS
