SERVICE MANUAL The    heated    automatic    drain    valve    will    activate    the heating element when the valve body is warmed to 30 C (85 F). MAINTENANCE 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. IMPORTANT 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. SERVICE CHECKS Operating Test With system charged, make several foot valve 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. Leakage Test 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 system. 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. REMOVE 1. Set parking brake or block vehicle while  service is being performed. 2. Drain air system. 3. Disconnect heater wire if valve is so equipped. 4. Remove automatic reservoir drain valve. REINSTALL 1. Block  and  hold  vehicle  by  means  other  than  air brakes. 2. Drain air system. 3. Thoroughly    flush    and    clean    reservoir    before installing drain valve. 4. 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. DISASSEMULY Refer to Fig. 12 for disassembly of valve and proceed as follows: 1. Remove four capscrews and lockwashers. 2. 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. 3. Remove valve guide. 4. Remove inlet and exhaust valve. 5. Remove adapter assembly. 6. If  the  automatic  drain  valve  is  equipped  with  a filter   and   retainer,   they   may   be   discarded   if desired. CLEANING AND INSPECTION 1. Cleaning solvent may be used on metal parts. 2. Rubber parts should be wiped clean. 3. Inspect    all    parts    for    wear    or    deterioration. Replace   all   parts   not   considered   serviceable during these inspections. CTS-4079-CHAPTER II- PRINTED IN UNTIED STATES OF AMERICA PAGE 8