Time to change the coolant in my 1997 C5. What is the proper procedure for re-filling and bleeding out the air. I don't have access to a shop manual.

Thanks!

Stephen

 

DRAINING THE SYSTEM
Drain the radiator using a 5mm allen to rotate the drain petcock about 1/2 turn or so counter clockwise. Coolant will come straight down the drain pipe. You will get about 1-1/2 to 2 gallons out.

If you also want to drain the block there are (2) plugs on each "side" of the engine block that need to be removed.
The first one is located on the passenger side of the engine above the starter, just below the cylinder head and uses a 5/16" allen socket to remove it. You can buy this 3/8 drive allen socket at sears for about $4. You should also remove the starter unless you want coolant to run all over it.

The second one is located on the drivers side toward the front of the engine kind of behind the alternator below the cylinder head. This one uses a 17mm allen. You can buy this allen wrench at sears for about $9.
Both plugs are kind of tight so take your time and they come right out. Put a little thread sealer on them before you tighten them back up.
NOTE - Do not remove the plug above the oil filter which looks like the ones mentioned above because oil will come out.

REFILLING THE SYSTEM
Pour in a 50/50/ mix of Dexcool/Water in the tank and allow it to fill the system. Burp the hoses to help remove the air. Leave the cap off of the tank and continue to add coolant as the level drops. When the temp reaches 170* slowly rev the engine to 3000rpm and back down. Do this 4 or 5 times to purge the air out and recheck the level in the tank. Add coolant as necessary until it is at the bottom of the tank screen. Put the cap on and then pat yourself on the back.

 

Quick question. If you run the car with tap water running in the radiator with the petcock turned won't it get all the coolant that is in the block? So then all you would have in the block itself is water. :confused:

 

:iagree:

:cheers: :cheers: :cheers:

 

Yes it will. I did this myself, last weekend when I was replacing all my hoses. After nothing but clear water was coming out for awhile, I shut off the engine and continued to let everything drain until it stopped completely. I put in approx 6.5 quarts of Dex-Cool (for a 50/50 mixture) and then refilled with distilled water (69 cents/gal at the store :)). Checked it several times over the next several days and everything's fine.
BTW, a 1/4" drive nutdriver fits the drain plug opening perfectly. Just remember that it is only a quarter turn to open. If it starts draining very slowly, just reach up an very gently (it's plastic) pry the drain plug out with a small screwdriver (or by hand if it's cold) until the flow is going faster. If you pry it all the way out don't worry. Just wipe it off and put it back in when your finished draining. To reinsert, it needs to be pushed into the hole until it stops, and then turn it 90 degrees to lock it. Just don't manhandle the plug or lose the o-ring it has on it and you'll be O.K. HTH!
Robert :)

BTW, turn your heater all the way to max hot while running the engine. I don't think we have heater control valves on our cars, but I didn't want to take any chances on old coolant staying in the heater core.