The heated automatic drain valve will activate the
heating element when the valve body is warmed to 30 C
Every six months or every 80,000 km (50,000 miles) the
automatic drain valve should be removed, disassembled,
cleaned and lubricated. Parts showing signs of wear or
deterioration should be replaced.
Early production automatic reservoir
drain valves were equipped with a filter.
Whenever service of any nature is
performed on the chassis, this filter may
be removed and discarded, if desired.
applications and note each time an application is made if
an exhaust or air occurs at exhaust port of the drain
valve. If no air comes out, push the wire stem. If no air
comes out, the filter is plugged and valve should be
removed and cleaned.
With system charged and pressure stabilized in system,
there should be no leaks at the drain valve exhaust. A
constant slight exhaust of air at the drain valve exhaust
could be caused by excessive leakage in the air brake
If the automatic drain valve does not function as
described, or if leakage is excessive, it is recommended
that it be removed and repaired or replaced.
Set parking brake or block vehicle while service
is being performed.
Drain air system.
Disconnect heater wire if valve is so equipped.
Remove automatic reservoir drain valve.
Block and hold vehicle by means other than air
Drain air system.
Thoroughly flush and clean reservoir before
installing drain valve.
Aerate any tank thoroughly if any solvents have
been used in the cleaning process.
When installing the reservoir automatic drain valve
equipped with a heater and thermostat, first determine if
the vehicle electrical system is a 12-volt or 24-volt and
that the heater/ thermostat unit is of the same voltage.
The No. 14 gauge lead wire on the valve should be
connected to the "on" position of the engine control or
ignition switch. Use an 8-amp fuse for one valve, a 15-
amp fuse for two valves and a 20- amp fuse for three
valves. All electrical connections must be waterproof.
Refer to Fig. 12 for disassembly of valve and proceed as
Remove four capscrews and lockwashers.
Remove cover and sealing ring.
If the heater or thermostat has failed, the entire cover
must be replaced. Do not remove the thermostat cover
plate. It is moisture sealed and removal could result in
early thermostat failure.
Remove valve guide.
Remove inlet and exhaust valve.
Remove adapter assembly.
If the automatic drain valve is equipped with a
filter and retainer, they may be discarded if
CLEANING AND INSPECTION
Cleaning solvent may be used on metal parts.
Rubber parts should be wiped clean.
Inspect all parts for wear or deterioration.
Replace all parts not considered serviceable
during these inspections.
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