Engine Rebuild, Break-In, and Tune-Up
CAUTION: Do not drain coolant until the coolant
temperature is below operating temperature.
Always loosen water pump drain valve (A) and
block drain valve (B) slowly to relieve any
IMPORTANT: Both water pump drain valve and block
drain valve must be opened to
completely drain the engine.
6. Remove and check thermostat(s). See REMOVE AND
TEST THERMOSTATS in Group 25.
Service Cooling System Safely
7. Drain and flush cooling system. See FLUSHING AND
SERVICING COOLING SYSTEM in Group 02.
IMPORTANT: Air must be expelled from cooling
system when system is refilled. Loosen
temperature sending unit fitting at rear
of cylinder head, bleed plug at top front
of cylinder head, or plug in thermostat
housing to allow air to escape when
filling system. Retighten fitting or plug
when all the air has been expelled.
8. Fill cooling system with coolant. Follow
recommendations in Group 02.
9. Run engine until it reaches operating temperature.
Water Pump Drain Valve
Check entire cooling system for leaks.
10. After engine cools, check coolant level.
NOTE: Coolant level should be even with bottom of
radiator filler neck.
11. Check system for holding pressure. (See PRESSURE
TEST COOLING SYSTEM AND RADIATOR CAP in
Group 105 of CTM134.)
Cylinder Block Coolant Drain Valve