1985-1998 [Subscribe to Daily Digest] |
The objective in flushing coolant is to remove ALL of the old coolant. There is no one single way to do it, but there are several things that will make the job easier.
First, drain the coolant from the radiator. The most important thing here is to unscrew the drain plug when the car is cold. Reason is the plug can be hard to remove when the radiator is hot. You can use needle nose pliers to remove the drain plug, the pliers will slip through the cutout in the plastic underneath the car. After the plug is out, you can loosen the expansion tank cap to speed the draining process. Put a tub underneath the drain plug to collect the old coolant. You want to dispose of the coolant in the sanitary sewer, don't let it drain into the storm drains.
After the radiator has drained, refit the drain plug (don't lose the o-ring that provides the seal) and fill the cooling system with clean water. Now you need to get the old coolant out of the engine block, since the coolant there will not drain through the radiator. The easiest way to do this is to buy a Prestone flush kit, and cut the heater hose so that you can insert a flush tee. Ideally, you want to cut the hose from the heater core back to the water pump ("upper" hose), but honestly it is a lot harder than cutting the hose from the engine to the heater core ("lower" hose). The flush tee is the outlet for the coolant. You need to stick a garden hose into the coolant expansion tank during flushing for make-up water. It does not need to go full blast, just enough to keep the coolant level up. The coolant level should be visible in the expansion tank during flushing. Now start the engine so that you have water pump pressure to force coolant through all the passages. Flush until clear water comes out of the flush tee, it may take 15 minutes.
I do not think it is necessary or advisable to "backflush." I would not recommend removing the thermostat, that in itself is a 90 minute job to remove and replace. When all the old coolant has been flushed out, put the cap on the flush tee and drain the radiator again. You are ready to fill with fresh coolant (use the extended life coolant, it is phosphate free). You can fill however you like, but do not dilute the coolant to 50% before adding it to the car. If you do, the water in the block will dilute it further and you will end up with less than 50% mixture. Add a gallon of coolant and how ever much distilled or deionized water is required to fill the cooling system. Done! Don't be surprised if the coolant level goes down a bit when you drive it after a coolant flush. Air is being purged from the cooling system and that takes a while. Just check the coolant level and top off.
If you really want to pamper the car's cooling system, use Prestone Superflush BEFORE you flush to clean the internal surfaces of the cooling system. It is a mild cleaner consisting of surfactants (detergents) and citric acid. On older cars, you will see noticably cooler operation after chemical cleaning/flush.
posted by 208.59.2...
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