What is the best way to fix a coolant leak, and what kind of
maintenance is recommended for the cooling system?
Vol. Per Cent Coolant Boiling
Point °F (at 0 psig)
Freezing Point °F
10
215
+25
20
217
+16
30
219
+4
40
222
-12
50
226
-34
60
231
-62
70
238
-84
80
250
-57
90
272
-33
100
330
-9
Replacing coolant on a regular basis will prolong the life of the
radiator and other cooling system components. Most new car
maintenance schedules call for coolant changes every three years or
50,000 miles. Many professional mechanics consider that too long and
recommend every two years or 24,000 miles.
There are some who argue that annual coolant changes on late model
vehicles with bimetal engines (aluminum heads/iron blocks) and/or
aluminum radiators is a good idea.
It does not really make much difference how often the coolant is
changed as long as it is changed before losing its corrosion
resistance. Antifreeze is made of ethylene glycol (which never wears
out) and various additives (which do wear out).
Some additives provide "reserve alkalinity" to neutralize internal
corrosion before it can start. As long as the coolant is changed
before its reserve alkalinity is depleted, the cooling system should
be no worse for the wear. If you wait too long, the result can be
expensive internal corrosion in the radiator, heater core and
engine.
How can you tell when it is time to change the coolant? The only way
to know if the coolant still has adequate corrosion protection is to
test it. By dipping a test strip in the coolant and noting its color
change, you can determine coolant condition and whether or not it is
time to replace it.
When coolant is changed, the system should be reverse flushed rather
than simply drained. This helps dislodge and remove accumulated
debris and debris in the system. It also removes old coolant that
would otherwise remain in the engine block.
Use of a cooling system cleaner is not necessary unless the system
has been badly neglected and is full of lime deposits.
The cooling system should be refilled with a 50/50 mixture of
ethylene glycol antifreeze and clean water. This provides freezing
protection down to -34 degrees F and boil-over protection to 265
degrees F.
When coolant is changed, inspect belts and hoses. Make a visual
inspection for leaks. Pressure test radiator and cap. Check
operation of heater and defroster.
The thermostat does not need changing unless it has been causing
trouble or the engine has severely overheated. If a thermostat is
replaced, it should have the same temperature rating as the
original. This is extremely important on late model vehicles with
computerized engine controls. Fuel, ignition and emission functions
are all affected by coolant temperature.
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