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Discussion Starter #1 (Edited)
Hello all,

Just recently bought a 2012 Volt (this past February) after reading tons of threads on this awesome site. I really like the car!

Brief Rundown:
170K on mostly the engine (30 lifetime MPG)
3 DTC Codes: P0131, P0137, and P0420
Changed Oil, Spark Plugs, and Air Filter
No mods except LED Headlights + Switchbacks
Little bit of oil residue around valve cover
Whistling noise when ICE runs
No Issues with battery/good range

I assumed the cat was probably going, but didn't think there would be other issues with the engine. Recently, I wanted to change the valve cover due to issues regarded on this site (and on cruzetalk.com) about the PCV valve in the engine (LUV 1.4L engine from Volt is used in Cruze) as it is making a loud whistling noise (from PCV inlet).

Yesterday, I wanted to verify the PCV inlet was actually causing the whistling noise, so I opened the hood and pulled the cover off the engine (intake still connected) and put my finger in front of the PCV inlet. Sure enough, that was the source of the whistling sound. However, I was checking the O2 sensors with my scan tool as the engine began to warm up (after 3-5 minutes of the engine running). But then, white smoke began BILLOWING out of the exhaust pipe and also rose from the engine bay and shut it off immediately. Not good. It smelled sweet, and seems that the head gasket is shot. But, the gas tank was also low (30 mi gas range left). I then proceeded to take the spark plugs out (Which I changed recently) and found the the 2 leftmost cylinders were wet, and the rightmost two were dry. New Code appeared: P0300 - Random Misfires Detected.

Given the circumstances, what seems to be the probable cause?

(a) Blown Head Gasket
- 2 wet spark plugs, white smoke from exhaust + engine compartment

(b) Bad Gas - ~ 1 Gallon left in tank, only filled tank once (93 Premium) after purchasing vehicle

What's so odd is it just happened now, and not when I was running in ER and ERDDT modes for the past month. And when I changed the oil (when I bought the Volt), it was not milky at all. In addition, the original spark plugs I took out were not wet and all looked fairly similar to each other. I plan on filling up with some good gas tomorrow and try running the engine again, and see if that changes anything. Thank goodness my commute is < 35 Miles, so I don't have to worry about driving in Extended Range mode in the meantime.


Thanks for reading! Also, more pictures + posts to come.

-17netters
 

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Sounds like the bad PCV valve is causing the engine to consume large amounts of oil. I would proceed with the replacement and I am 90% sure it will fix all of your issues.
 

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Discussion Starter #3
Typo: P0400 should be P0420.
 

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Oil smoke is usually blue, excess gas is blackish, and water is whitish... Sounds like a head gasket to me.
 

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Discussion Starter #6
AlmostEV - I thought that might of been the issue before, but IMO there is too much smoke to be a PCV issue.

Tomt - I've seen that posted elsewhere, which makes me believe that a blown head gasket is the probable cause.

srmarti - I'll see if I can rent a leak down tester this week, considering that it could be a good way to verify a blown head gasket.

I've also been considering replacing the engine, as there are some volts in scrapyards near me.
 

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Discussion Starter #7
Update:

After filling up with a full tank of 93/Premium gasoline, I ran the engine for about 15-20 minutes. It first started smoking a ton at first, but then began to clear up. Before I started the engine, I cleared the codes and the P0300 code didn't come back. So apparently, whatever is in the tank is pretty bad.

Considering that when I bought the Volt from the dealer, the tank was only a 1/4 full, which that gas probably was old and had water in it. In addition, I haven't filled the tank in about 2-3 weeks when it was low, so there might have been some additional condensation buildup.
 

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Good that it sorted out on the happy side and thanks for posting the results.
Was there a real stink to the old fuel? I had a generator on my motor home that had not been used for years. The gas stunk so bad when I finally got it running. Actually had to drain the fuel tank.
 

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Discussion Starter #9
Manitoba Keith- Yes, it actually smelled pretty bad when it started burning out the old gas... once it stopped smoking it stopped smelling bad.
 

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Oil smoke is usually blue, excess gas is blackish, and water is whitish... Sounds like a head gasket to me.
Agreed... mostly.

A compression check will help determine if there is/are leaks from cylinders, and maybe where. Has the coolant level changed? Does it have oil in it? Also, check the oil for coolant.

Many years ago, I had a Dodge Omni that worked well from many years, until one day, it would barely idle, and had no power. I performed a compression test, and found a leak between adjacent cylinders. The mechanic suggested that the coolant had eroded the cylinder block under the head gasket. The coolant had never been changed over the life of that engine (about 8 years).

My Volt was at the dealer a month ago for a failed 12V battery (6yr old, and I'd seen it coming - Arg!). The dealer was pushing for urgently needed brake fluid and transmission fluid replacements (neither due for a couple years), but had neglected to mention the coolant was slightly overdue for replacement (6 months past the 5 year due date).

I think dealers may be reluctant to replace the coolant. Given the special equipment necessary, and the "Service HV Charging System" tech bulletin (which also happened to me), I might understand why.
 
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