2008 Chevy Cobalt LS Coupe
app. 88,500 miles
2.2L DOHI Ecotec
5 Speed Manual
So, after buying a Haynes Repair Manual and reading the suggestion that the coolant be flushed every 30,000 miles, I've decided to tackle the job myself. It's never been flushed/refilled since I've owned it (I made the mistake of buying brand new, but that's another headache for another time). The coolant was filled well-above the cold mark. I only drained from the bottom of the radiator (passenger side) and did not drain any additional coolant from the water pump. After the coolant finished draining, I closed the drain valve. I refilled with cold filtered water at the "cold mark" on the expansion tank. I started the engine & let it run idle until it got to about 160 degrees. From there, I revved the engine at about 2500rpm for about 30 seconds, & a few short times until the temp got to 180. I shut the engine off, looked underneath, and saw water leaking from behind the engine. It was water, without question. It was leaking from some opening facing outward towards the engine, dripping down to the frame. Later, I noticed water dripping near the exhaust. It dripped quite a bit when the engine was running & eventually stopped when turned off. Both radiator hoses, the radiator itself, and the water pump looked fine. Oil looked great & was within normal level (I changed it myself yesterday). For what it's worth, I cheaped out & got the $17 crap oil change a couple months ago and felt guilty about it, so I used Mobil 1 oil & a Mobil 1 Extended Performance filter this time.
Not sure what I did wrong, or if the flush just exposed a leak due to the build-up from the old coolant. Any constructive feedback is welcome. Thanks!