Hey everyone, I just received a letter in the mail from GM telling me to get a radiator flush. I went to my regular mechanic and he said he will do it. Although he did say he'll remove my thermostat and stick a garden hose in and drain it the old fashion way. I'm looking to see if I can flush it myself. I remember reading someone using distilled water to flush their radiator. What should I do?
Thanks
T.J.

 

I've only used distilled water in my vehicles, but then again I'm an **** S.O.B.

 

I only use distilled as well. $0.58/gallon at Wally World. I don't like the "put in the garden hose" method, and prefer to go by the service manual. Haven't read up on my C5, but on my C4 it was drain system, refill with water and run car. Cool down, drain and repeat until system is clear. Then drain and fill half capacity with 100% coolant to obtain the 50/50 mixture. Took me a couple of days to do the whole thing, but wasn't too hard except for recycling all that coolant mix.

 

Check this out...

http://www.idavette.net/hib/C5diy/c5diy1.htm

 

If you drain the radiator then remove the two bolts that hold on the thermostat/ housing you can flush the entire systen using a garden hose without starting the engine. By covering the various ports with your hand and aiming the water in the other ports the old coolant will be flushed out of the block, heater core and radiator. When the water comes out clean from all areas replace the thermostat/ housing and two bolts. Refill with new coolant and tap water.

 

When you drain the radiator, you only get about half the coolant out of the system. If that's all you intend to do, then refilling with a 50-50 mixture is the correct procedure. However, you now have a coolant that is 50 % old antifreeze and 50 % new antifreeze. Since I do not like this, I use a garden hose to flush the whole system with the engine running, the heater on and the petcock open. After about 10 minutes, the water comming out of the petcock drain is very clear. You should also siphon all the coolant out of the recovery tank so that it is clean. Shut off the water and the engine and let the radiator drain all it can. I then pour 2-3 gallons of distilled H2O into the recovery tank, and since it is the highest point of the cooling system, the distilled water backflows through the system, hopefully forcing out all the city water. At the least, the water left in the system should have a smaller percentage of chlorine and other dissolved minerals than the city provides. Let the radiator drain again for the last time, then close the petcock. Fill the radiator and recovery tank with approximately 7 quarts (1 3/4 gallons) of Dexcool and you are finished. After a short running time, the full strength Dexcool in the radiator will mix with the fairly pure water in the rest of the system. Additional runs and shut -ffs will mix the full strength Dexcool in the recovery tank into the rest of the system, giving a 50-50 mixture.