I'm in the process of changing the timing belt, idler, water pump on my 2005 Aveo. I figured since I was changing the water pump, might as well flush the cooling system.
Timing belt change went without a hitch. Cooling system is another story. About half way through the belt change, I noticed a leak from the rad. I first I thought it was coming from the stop cock, but I later learned it was coming from the rad (water dripping). When I refilled the colling system with 50/50 DexCool, the bottom three inches of the rad fins turned red from the DexCool and eventually I could see a leak spewing coolant in the rad (when the car was running). The rad doesn't leak when the car is not running.
For the flush, this is the procedure I followed:
- I used Prestone Super Flush and followed the instructions
- after using the Prestone and waiting for the system to cool, I did a modified system "rinse/flush" by hooking a garden hose up to the pickup line running to the pressurized remote surge tank. I dis-connected the return line the goes from the rad to the remote tank - this is where the system was discharged into a 5 gallon pail. I blocked off the other return line the ran from the manifold. I started the car and ran the flush until the water ran clear.
- I drained what I could from the system via the stop cock on the bottom of the rad - I closed the stop cock after the system drained.
- the motor and rad stayed empty over two nights while I worked on the timing belt, etc.
- nighttime temps hovered around freezing, but above freezing in the garage - I had water laying in a bucket and there was no ice forming.
So here are my theories:
1) Prestone Super Flush is not really compatible with aluminum components and rads and it "ate" my rad (unlikely).
2) Prestone Super Flush is really good at what it does and any "gunk" that was plugging leaks in the rad was washed away and the rad leaked.
3) Despite draining the rad and (hopefully) the block, water in the rad froze and burst some of the tubes that still has water in it. I doubt this, since there wasn't even a skim of ice on the water I had in the garage. Also, the thermometer I have in the garage never went below freezing.
4) I damage one of the fins that damaged a tube.
What do you guys think happened?