Century V6-231 3.8L (1985)
Thermostat: Customer Interest
A/C - Poor Heater Performance
Bulletin 85-1-12
Date Mar. '85
Ref.. No. 85-079-1
SUBJECT:
HEATER PERFORMANCE
MODELS AFFECTED:
1985 ELECTRA WITH 3.8L MFI, V-6 ENGINE (LN3) 1984 & 1985 CENTURY WITH 3.8L MFI, V-6 ENGINE
(LN3) 1985 REGAL SOMERSET WITH 3.0L MFI, V-6 ENGINE (LN7)
195~ THERMOSTAT ON 3.8L MFI (LN3) ENGINE
Recent changes on the LN3 engine used in the Electra and Century, have resulted in changes to heater performance in cold weather. A 195~ F. high
bleed rate thermostat assembly has recently replaced a 180~ F. thermostat.
If a comment of poor heater performance in cold weather is received, install thermostat part number 3041390, and replace coolant outlet gasket, part
number 1250390. Refill engine cooling system with proper coolant and ensure that all trapped air is expelled. Check coolant protection level for
adequate protection.
PROPER COOLANT FILL
On the Electra, Century and Regal Somerset, as well as other models, care should be taken to remove any trapped air from the engine cooling system. Air
trapped in the heater core can significantly degrade heater performance and cause heater temperature cycling. To ensure adequate fill and remove
trapped air, use the following procedure:
CAUTION: Use proper precautions to help avoid the danger of being burned when removing or installing radiator cap and when expelling any trapped
air.
1.
Remove radiator cap. If engine is hot, allow it to cool down until radiator cap can be safely removed. Top off coolant in radiator to within 3" of the
top.
2.
Place HVAC controls in A/C mode, or auto on C68, and temperature to highest setting.
3.
Start engine and allow it to warm up while idling until thermostat opens. Coolant level in radiator will rise somewhat when thermostat opens. In
cold ambients, run until radiator core is hot to the touch.
4.
Allow engine to continue idling until lower radiator hose to water pump is hot.
5.
Cycle the engine speed up to about 3000 RPM five times, and back to idle. This should expel any trapped air in the system.
6.
After the air has been expelled, fill the radiator, check the protection level, and install the radiator cap. The fan may not cycle in cold ambients.
7.
Fill coolant overflow reservoir to the hot level. Check for any coolant leaks with engine running.
Coolant bypass from the intake manifold to water pump is being added on the LN3 and LN7 engines for coolant temperature cycling.
