Subaru Impreza 2003 Service Manual page 102

PERIODIC MAINTENANCE SERVICES
2. RELATIONSHIP OF SUBARU COOLANT
CONCENTRATION AND FREEZING TEM-
PERATURE
The concentration and safe operating temperature
of the SUBARU coolant is shown in the diagram.
Measuring the temperature and specific gravity of
the coolant will provide this information.
[Example]
If the coolant temperature is 25°C (77°F) and its
specific gravity is 1.054, the concentration is 35%
(point A), the safe operating temperature is −14°C
(7°F) (point B), and the freezing temperature is
−20°C (−4°F) (point C).
(2)
1.100
1.090
1.080
1.070
C
1.060
(1.054)
(1)
1.050
1.040
(4)
1.030
1.020
1.010
1.000
-40 -20 -10
-30
(-40) (-22) (-4) (14) (32) (50) (68) (86)
(1) Coolant gravity
(2) Safe operating temperature
(3) Concentration of coolant
(4) Freezing temperature
(5) Coolant temperature
(3)
60%
B
50%
A
40%
30%
20%
10%
0 10 20 30 40 50
(104) (122)
(5) C ( F)
PM-00025
COOLANT
3. PROCEDURE TO ADJUST THE CON-
CENTRATION OF THE COOLANT
To adjust the concentration of the coolant accord-
ing to temperature, find the proper fluid concentra-
tion in the above diagram and replace the
necessary amount of coolant with an undiluted so-
lution of SUBARU genuine coolant (concentration
50%).
The amount of coolant that should be replaced can
be determined using the diagram.
[Example]
Assume that the coolant concentration must be in-
creased from 25% to 40%. Find point A, where the
25% line of coolant concentration intersects with
the 40% curve of the necessary coolant concentra-
tion, and read the scale on the vertical axis of the
graph at height A. The quantity of coolant to be
drained is 2.12 (2.2 US qt, 1.8 Imp qt). Drain 2.1 2
(2.2 US qt, 1.8 Imp qt) of coolant from the cooling
system and add 2.12 (2.2 US qt, 1.8 Imp qt) of the
undiluted solution of SUBARU coolant.
If a coolant concentration of 50% is needed, drain
all the coolant and refill with the undiluted solution
only.
(3.2,2.6)
(1)
(2.1,1.8)
(1.1,0.9)
(1) Quantity of coolant to be drained
(2) Necessary concentration of coolant
(3) Concentration of coolant in vehicle cooling sys-
tem
PM-26
(US qt, Imp qt)
(2)
3
45%
A
2
40%
35%
30%
25%
1
20%
15%
10%
0
10 20 30
(3)
40 50
%
PM-00026