Rad Leaking After Coolant Flush

whitefish · April 5, 2010

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?

bluArrow · April 5, 2010

5) The car is a $6000 Korean import manufactured by Daewoo that used cheap components because it was(is) built to a price point.

I'm going to go with number 5. Anyway, it's off to the dealer for a new radiator.

whitefish · April 5, 2010

GM puts stop leak from the factory in its vehicles. Did you replace it when you flushed?

Really? The GM DexCool literature I read specifically said not to add any additives to the coolant.

Even if I added stop leak, I don't think it would stop this size of leak (can actually see a stream of coolant coming from the rad at operating temp).

I agree about these cars being a POS. Spend nothing on the car and spend it all on parts. Never again.

whitefish · April 5, 2010

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!

Nytemare · April 5, 2010

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!

pretty sure your right on the compression washer

and I believe it takes about 1 quart in the cooler, maybe a little more, 2 Quarts would definitely be enough. That trans doesn't have a dipstick either does it. If you over fill the trans slightly it doesn't make much difference in those cars.

whitefish · April 6, 2010

Thanks Nytemare,

Yes, the tranny has a dipstick. Didn't look like there was a quart of oil in the cooler. Maybe most of it drained back into the transaxle???

The dipstick shows enough oil at cold - will have to test after warmed up. I'll take some ATF with me tomorrow on my commute (only 20 miles) just in case.

Nytemare · April 6, 2010

Thanks Nytemare,

Yes, the tranny has a dipstick. Didn't look like there was a quart of oil in the cooler. Maybe most of it drained back into the transaxle???

The dipstick shows enough oil at cold - will have to test after warmed up. I'll take some ATF with me tomorrow on my commute (only 20 miles) just in case.

Cool...at least you got a dipstick...that's one thing your "cheap POS Daewoo made Chevy" gave you over a real Chevy...

Those sealed for life trans-axles are the stupidest idea ever.