405 L4-1905cc 1.9L (1989)
Thermostat: All Technical Service Bulletins
Thermostat Housing - Coolant Leak
BULLETIN NO. 434
DATE:
DECEMBER, 1991
SUBJECT:
COOLANT LEAK FROM THERMOSTAT HOUSING
MODELS:
ALL 1989,1990 AND 1991 MODEL YEAR 405 VEHICLES UP TO VIN 0518560
COMPLAINT:
Under certain conditions it is possible for the thermostat housing to develop a slight leak. This may eventually cause a significant drop in the radiator
level, leading to illumination of the coolant level warning light or, in extreme conditions, overheating.
In addition, Mi16 vehicles may experience erratic cooling fan operation due to leakage from the housing to the temperature sensor.
CORRECTION:
On 1991 model year vehicles built as of VIN 0518560, the factory has installed a reinforced thermostat housing and a new style seal. The new seal is a
one-piece unit that fits around the circumference of the thermostat instead of the two o-ring style seals that were used on the 1989, 1990 and early 1991
models.
REPAIR:
Install the new style thermostat housing and seal. This will require the addition of an adapter plate available under part number 0013.01.
PARTS REQUIRED:
Part Number
Description
Qty
0013.01
Adapter Plate
1
1336.87
T-stat Housing - J2 manual
1
1336.88
T-stat Housing - J2 automatic, J4
1
1339.53
T-stat Gasket - new style
1
1339.10
T-stat Gasket - original style
1
1338.11
Thermostat - J2
1
1338.03
Thermostat - J4
*
6921.83
Bolts
2
6947.22
Washers
2
5404.02
Bleeder Cap
1
6981.41
Clamp
1
*optional
PROCEDURE:
-
Loosen radiator stopper to partially drain cooling system
-
Retighten stopper securely
-
Remove and discard the thermostat housing, seals and bolts
-
On J2 vehicles, discard tbe thermostat
-
On J4 vehicles, inspect the top cover of the thermostat in the area of the locating pin for signs of cracking; replace only if necessary
-
Wash adapter plate thoroughly with warm soapy water to remove any particles left behind by the machining or burnishing process
-
Install a new original style seal (1) (P/N 1339.10) on the engine block side of the thermostat's coolant housing
-
Place the adapter plate (2) on the housing so that it contacts the seal; be sure to line up the bolt holes
-
Install the new style seal (3) (P/N 1339.53) around the outer circumference of the thermostat
(4) and place it into the adapter plate
-
Install the new style thermostat housing (5) with the longer bolts (6) and washers
-
Tighten the bolts to one daN-m (7.37 ft.lbs.)
