I was taking off from several stop lights on the way home today, not really even getting on it, and all of a sudden it "sounded like a Suburu" to steal a phrase from someone else. This sound persists, and luckily I was almost home, a couple miles or so, because I noticed the coolant temp rising. It got almost to 250 before I shut it off. I saw the coolant boiling, overflowing, whatever, and let it cool off a bit. I started it back up and it made some ticking sounds near the right side, by the oil cap, and then started howling a little like if you were blowing on the opening of a bottle. I got the car backed into the garage and noticed at that time the low coolant light had come on. The only coolant I noticed leaking anywhere was out of the overflow. I checked the dipstick and it looked ok.

I started thinking about it and thought maybe the water pump went out. I am not sure if that would make the exhaust sound change, though.

 

The subaru sound usually comes from the car running on 3 cylinders, a lot of times caused by a lifter breaking and preventing a valve from opening. However, that wouldn't cause coolant issues. I almost want to say you might be plagued with the porous block issue but that should show on your dipstick. All I can suggest is pull the valve cover just to check everything under there and maybe do a compression and leakdown test to see if you come up with anything out of the ordinary

 

Yeah the Subie sound is usually a lifter, but with the coolant issue, it's probably time to start looking at everything. Find the coolant leak, if you can't, it's probably internal to the engine.

Check oil, check spark plugs, do a compression test.

Also pull the valve cover and look for broken pieces.

Have a fun weekend.

 

The "subaru sound" and running poorly sounds like you may have a valvetrain problem, broken lifter?

I don't know what's wrong with your car but this is the order i would check things, probably from easiest to hardest (or at least for me)
- take off the valve cover and see if any lifters are bent / fell off.
- it kinda sounds like you may have skipped a tooth on the timing chain, check timing next?
- compression test maybe? people break ring lands on these engines if they push too much boost, but usually not at stock boost level, i'm guessing a broken ring land would show up in a compression test? or maybe a boroscope in the combustion chambers? (i'd borrow a compression test tool from the local autozone, a cheapo boroscope is 7 bucks on ebay)

Get the engine running first, then you'll deal with the overheating problem which i think is a separate issue. Everyone is paranoid about the "pourous block" it's not nearly as common as you would think, there are what 20? maybe? known cases, out of THOUSANDS of cobalts... When i first bought the cobalt, on a very cold day my coolant light came on, car was low on coolant, i added some, it has been the same level for 2 years now. guess what, just cause my coolant light came on, doesn't mean i had a porous block, it's been fine for 2 years.
If you have a pourous block, like the other thread you posted in, you saw that the guy had to refill his coolant DAILY. So like i said get the engine running first, then we'll see how much coolant, if any, it consumes.

 

Roughly 1% of 08-09 Cobalt SS Turbos had porous blocks. We have maybe 20 on here but that doesn't include the tons of others that aren't on this site.

That doesn't sound like a lot but it is.

 

I heard something pop, possibly a chain. Could be timing... sound from exhaust got low and hollow sounding, not higher pitched and peppy like usual. Then got hot and coolant got low. I am hoping it's something easy to fix and the coolant loss was simply it getting hot and boiling out.

It is going to take me a long time to troubleshoot this, but, I appreciate all the feedback, and I will work on it as I get time. I don't have any mechanic buddies so this is not going to be fun.

 

If the timing chain broke I wouldn't have been able to drive it the 1-2 miles the rest of the way home, would I ? Is the water pump chain-driven?

 

Water pump is chain driven but on a separate chain from the timing. It is connected to the balance shafts and crank shaft. But to answer your question, if the timing chain broke, no you wouldn't be able to drive it

 

I've blown a spark plug out of the head before, and ended up with the same lower/hollow exhaust sound, but i also had flashing CEL and basically zero power. horrible to drive in that condition, IF that were the case. A new coil pack fixed it. go with these guys ideas first though, i'm definitely not gonna claim to know it much lol

 

If you physically blow a spark plug out of the head, that's gonna take more than a coil pack to fix it

 

Thanks for the help!

To be a little more specific, this is what happened:

1) I was accelerating from a stop, and I heard something give. I can't remember exactly what kind of sound it was, but it was obvious. Immediately I heard the difference in the exhaust sound.

2) I had to stop and go several more times before I got home. Other than the sound, and the smell of coolant, everything seemed normal, including boost, etc. Maybe there was a loss of power, but it wasn't enough for me to really notice. About that time I noticed the temperature rising.

3) The temperature got to about 250 before I got it in the driveway and turned it off. At that time I looked under the hood, and didn't notice anything except the coolant was coming out of the overflow. I plan on doing another check later today to see if I missed anything.

4) I started the car back up, and listened to the engine. That's when I noticed an odd sound, kind of a tick that was out of place, on the right side in the vicinity of the oil cap. Pretty soon I heard the hollow whistle like if you were blowing on the opening of a bottle. I assume this was steam in the cooling system somewhere. I didn't nail down exactly where it was coming from as I turned the engine back off right away.

5) After sitting there for a while in disbelief, according to the temperature sensor it was back down under 200 degrees. I realized I couldn't leave the car there like that. I started the car back up, backed it out of the driveway into the street, turned it around, and backed it back into the garage. During that time I didn't notice the whistle sound or anything, and according to the temp sensor reading it didn't rise that much more in temperature. As I was backing the car in is when I noticed the low coolant warning had popped up.

It "seems" to be running ok other than the odd exhaust sound, and the overheating.

I know your time is valuable, and any input or opinion is a great help. As I said before this is going to be a slow process for me, but the more information on possibilities I have, the better spent my time will be when it comes to trying to troubleshoot the problem.