Rad Leaking after System Flush - 2005 Aveo

[whitefish]

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?

[Thymeclock]

I'd say it's either #2 or #4. Even if it were below freezing, any water left in it would have had room to expand, so it would not have burst a tube.

Five years seems too soon for a radiator to go bad, however.

[whitefish]

I'd say it's either #2 or #4. Even if it were below freezing, any water left in it would have had room to expand, so it would not have burst a tube.

Five years seems too soon for a radiator to go bad, however.

I agree about the freezing and about the rad going in 5 years. Seems too coincidental that it would leak after the flush. I'll give Prestone a call tomorrow. I would be surprised that leaning on the rad fines while I loosened the stock cock would do that much damage to the rad!

I had another question on the rad replacement:

I have an auto with ac. It appears that the AC condensing unit is in front of the rad with the trans cooling lines going into the rad. Is the ac condensor and rad separate or one unit? GM references a "1st design", assuming that there is a second design? Which is which?

Thanks!

[petrified.rabbit]

condenser is separate but they are bolted together.

The auto tranny lines, the cooler is in the end tank? so if it is, you need an automatic specific radiator.

As for your leak, where is it leaking? I would guess if it was THAT cold, and you turned the drain the plastic might have cracked. Since it had age, and temperature against it. All of your theories "work" though, but where the leak is will let you the problem, not someone guessing on the internet.

[whitefish]

condenser is separate but they are bolted together.

The auto tranny lines, the cooler is in the end tank? so if it is, you need an automatic specific radiator.

As for your leak, where is it leaking? I would guess if it was THAT cold, and you turned the drain the plastic might have cracked. Since it had age, and temperature against it. All of your theories "work" though, but where the leak is will let you the problem, not someone guessing on the internet.

At first it was difficult to see exactly where the leak was, but after the engine got up to temp, there was a small stream of antifreeze coming from one of the tubes near the bottom of the rad. The leak was at a fin, which makes me think I may have accidentally damaged the fin which damaged the tube. The leak is not at the plastic drain.

[mikedudley17]

Well at this point we can establish that the radiator is bad so instead of hunting for answers id be hunting for a radiator. Guessing what is wrong with the radiator wont fix it. If its cracked id be checking out components around the coolant system. Plastic parts will become brittle over time.

[Thymeclock]

condenser is separate but they are bolted together.

The auto tranny lines, the cooler is in the end tank? so if it is, you need an automatic specific radiator.

As for your leak, where is it leaking? I would guess if it was THAT cold, and you turned the drain the plastic might have cracked. Since it had age, and temperature against it. All of your theories "work" though, but where the leak is will let you the problem, not someone guessing on the internet.

At first it was difficult to see exactly where the leak was, but after the engine got up to temp, there was a small stream of antifreeze coming from one of the tubes near the bottom of the rad. The leak was at a fin, which makes me think I may have accidentally damaged the fin which damaged the tube. The leak is not at the plastic drain.

Fins don't leak, but the tubing will, if perforated.

You do see an actual stream of liquid escaping? This is a long shot guess: sometimes, for example if that drain cock is leaking, fluid can be diverted, possibly squirting up in a narrow stream that might appear to be coming from elsewhere. Check the drain cock and particularly the seal on it. If the seal is distorted it will leak.

If it's not the drain cock, you have 3 choices: Add a leak sealant additive and pray it works, remove the radiator and have it professionally repaired, or install a new radiator.

[whitefish]

Thanks Thymeclock. Yes I can see an actual stream of coolant. Couldn't at first, but when the car got up to temperature it appeared. At first I thought it was the drain plug as well, so I replaced the o-ring. No dice.

mikedudley17 - I guess I'm asking questions on the net to determine whether or not people have had problems with Prestone Super Flush. Or, I was a little concerned that water may have froze in the tubes and caused a crack that way. Don't want to make the same mistake twice, but sort of need to know if I made one in the first place.

At any rate, have a new rad now. Let you guys know what I found on the old one when I pull it out.

BTW, anything special that needs to be done when pulling and re-installig the tranny cooler oil lines?

[whitefish]

Problem solved. There was a pinhole leak in the rad. Not sure how it got there, but its there. The new jobber rad I got was an exact replacement - drain plug and everything. Replacement went without a hitch.

Quick question - I have a little weeping around the inlet for transaxle oil cooler line (the one the bolts on, not the return). Is the washer a compression washer (i.e. use once and throw away)? If so, I guess I would need to replace.

Also, how much oil is in the oil cooler - just wondering how much I need to top up the oil in the transaxle.

Thanks again!

[mikedudley17]

Good to hear everything went well. Do you remember how you made the radiator swap? I ask this because I bet a nice how-to could be had from this for others who may run into this problem. Even though its a somewhat simple project, some people can be intimidated by the work and fear not being able to do it correctly so they end up spending the money to take it to a mechanic.