2012 Chevy Sonic - Ignition-system Problems

[Number_35]

Our friends' 2012 Sonic (NA 1.8 l automatic c. 120K km) has been marooned out at their daughter's family home in a small town near here. It would start but ran very poorly, and the check-engine light flashed, indicating a misfire.

I advised them not to drive it back, as the misfire could quickly ruin the cat.

I was finally able to get out there this afternoon. Removed the original plugs (NGKs) - all four were black and wet, one of them dripping with oil, and another moderately covered with oil. The electrodes didn't look too bad though. I figured the oil seals at the bottom of the spark plug wells were leaking. My friend had bought new AC plugs in advance, and we installed them. The car started fine, but ran roughly, again indicating a misfire.

My friend ran over to a local parts store, which fortunately had the coil pack in stock. (It's a single unit on the Sonic, so I couldn't troubleshoot by swapping individual coils to see if the misfire followed the coil.)

Anyway, the new coil pack fixed the misfire, and the car runs well now.

But, I'm concerned about the oil leakage.

I think it's quite possible the valve cover gasket failed (it's a one-piece unit which includes the four spark plug oil seals), which caused the plugs to get saturated with oil and misfire, which stressed the coil pack, causing it to fail. If that's the case, it's important that we change out the VCG as soon as possible.

Further, I watched a YouTube video later, which showed that the PCV valve is integrated into the plastic valve cover. I hypothesize that if the PCV valve gets blocked, the blowby pressure could blow out the spark plug gaskets, resulting in oil-fouled plugs and eventually another failed coil. Make sense?

Who's got experience with this engine? Apparently the normally-aspirated 1.8 was also used in the more-common Cobalt.

Does it make sense that a blocked PCV valve would cause this chain of events, or is it more likely just coincidence?

If the PCV valve portion of the VC is blocked or even iffy, can I clean it with TB cleaner, etc., or is it best to change the VC out?

Thanks in advance for your thoughts.

 

[GMBoy]

The PCV issue is much more common on the 1.4T motor, basically every one fails eventually. I have only seen one 1.8 bad valve cover so it can happen. I would for sure do the new valve cover because it is not expensive and you get new gaskets solving the leak issues....not much more expensive then just doing the gaskets alone.

 

[JoelB]

On a random side note I would suggest inspecting the intake elbow for cracks. It was a common problem on the 1.8 for a few years. My wife's sonic was getting a random lean code and it turned out it had split in one of the "ribs". New ACDelco unit off rockauto fixed it up.

 

[GMBoy]

On a random side note I would suggest inspecting the intake elbow for cracks. It was a common problem on the 1.8 for a few years. My wife's sonic was getting a random lean code and it turned out it had split in one of the "ribs". New ACDelco unit off rockauto fixed it up.

Yep! I forgot that. I have seen that as well...plastic just disenegrates

 

[Blinker]

The cobalt used the 2.2 Ecotec, which are very different.

Has the timing belt ever been changed?

 

[Number_35]

The cobalt used the 2.2 Ecotec, which are very different.

Has the timing belt ever been changed?

Ack, you're right, I meant Cruze, not Cobalt. At least I didn't say Cavalier or Monza ... or Vega.

My friend bought the car new - I'm pretty sure the timing belt is original. I think it's rated for around 150K km, so mileage-wise it should still be good, but I'll mention to him that it will need to be done at some point. Do you know if it's an interference engine?

 

[Number_35]

My friend brought the car over to my place on Saturday, and mentioned that it had started making a bad noise once he reached town after driving in from the country. It sounded like an accessory bearing on the way out.

But then I checked the oil, and found it off the dipstick. Added a couple of litres but called my friend and recommended an oil change - he brought over a 5 l jug of synthetic 5W-30 (the weight recommended on the oil filler cap on the valve cover) and a cartridge filter. And then of course I worried that the noise was the result of running the engine with low oil ...

As well, the coolant reservoir was effectively empty, and the there's no cap on the rad so it's hard to tell how low the level actually is. (A glance at the reservoir is misleading - the hose to the rad leaves the reservoir partway up, so although you can see coolant in the bottom of the reservoir, that coolant cannot be drawn into the radiator.) So I thought I'd do a drain and fill, and so asked my friend to pick up a jug of premixed Dex-Cool equivalent.

The car has no temperature gauge, so it's hard to know whether or not it got dangerously overheated. I suppose if it were that bad, the idiot light would have come on.

But first things first - I changed the valve cover gasket, which went fine. Just the little bit of driving the car had done since the ignition repair had caused the spark-plug wells to start collecting oil again. The round gasket sections around the spark-plug wells were hard and brittle. The top of the head was pretty grungy.

Then I did the oil change - took 5 l with the filter. Both the drain plug and the plastic filter housing were on way too tight for my liking. The oil didn't look too bad streaming out, but then I realized close to half of it was the new oil I'd put in the day before.

Then I tried to track down the noise, still hoping it was an external accessory. I was unable to isolate the source with my stethoscope, and was unsuccessful in trying to remove the serpentine belt without a dedicated tool.

Sunday I bought the cheapy serpentine-belt removal and installation tool from Canadian Tire. The thin-walled 13 mm socket split immediately. I returned the tool, and bought a much better one from Princess Auto. (PA had two levels of the tool - the low-end one looked much like the one I'd broken, so it was an easy decision to buy the better one.) Like night and day. Was able to remove the belt easily with the good tool.

The only belt-driven accessories are the water pump, the tensioner, and the alternator. The car does not have AC or PS.

The WP and tensioner spun smoothly and quietly by hand. The alternator made some noise, though it didn't feel rough. I went ahead and pulled the alternator. Pretty tight - I donated some skin and blood to the cause.

This morning I found a local starter-alternator specialist who did the job for about 2/3 the cost of the cheapest rebuilt or new unit we could get locally.

I installed the alternator this afternoon, drained the rad (only got a couple of litres out), and then refilled the rad. Went through quite the burping procedure (the cooling system rather than myself) and am satisfied there are no air pockets left. There's a little plastic plug near the top of the rad to facilitate purging the system of air.

So now the car's running well and quietly. I hope the low oil and coolant didn't significantly shorten the engine's life.

Photos to follow!

 

[Number_35]

Here's the new valve-cover gasket:

Oil is starting to infiltrate the spark-plug wells only 50 km or so after the plugs were changed:

The old valve cover was quite dirty inside, and the old gasket was very brittle in places:

The head had more black crunchy carbon grit than I would have liked:

Here's the alternator, dropped down for access to the electrical connections:

The alternator is removed and reinstalled through the gap in front of the brake hose and behind the harmonic balancer (crank pulley):

View from above, after alternator removal, with the air box removed - the alternator isn't coming out the top!

 

[Number_35]

The PCV issue is much more common on the 1.4T motor, basically every one fails eventually. I have only seen one 1.8 bad valve cover so it can happen. I would for sure do the new valve cover because it is not expensive and you get new gaskets solving the leak issues....not much more expensive then just doing the gaskets alone.

I should have taken your advice; in trying to save my friend some money, I replaced only the VC gasket.

I've since done more research - there are a number of YouTube videos, and Sonic/Cruze forum threads out there, all indicating that the integrated PCV valve is fragile and fails frequently. There are discrete replacement units available, but it seems that most people are not successful in getting it to seal, so they wind up buying a new valve cover anyway.

I did blow and suck through the PCV tube when the VC was off, and noticed that there was airflow both ways. I'd assumed that rather than a valve it was just a port with a fixed restriction.

So, it appears the PCV membrane has failed. (The car has 125K km [ c. 78K miles] on it, and the folks online say these often fail between 60K and 80K miles.)

Given that it's failed open, what problems will that cause?

The engine does have some significant oil leaks, which would explain why it was down 2 - 2-1/2 litres, and I'm wondering whether the open PCV valve could be the cause. (I understand that if the PCV valve were blocked, the crankcase would be pressurized, and oil leaks would result, but I don't know whether an open valve would also cause oil leaks.)

Another thing is that the oil filler cap on the VC looks to be slightly concave, like there's suction happening.

My friend is going to bring the car over, and I'll do more investigation. He is discouraged about what he's already had to spend, and would like to avoid buying a new valve cover if possible.

Thoughts? Any Chevy 1.8 specialists out there? Thanks in advance.

 

[Number_35]

I checked the Sonic again today - when the engine's running, there's a significant amount of suction under the valve cover, making the oil filler cap hard to remove.

There's no apparent suction (again with the engine running) when one pulls the dipstick.

I don't know whether the integrated PCV valve is supposed to act like a simple modular PCV valve (i.e. like a one-way valve) or not. I was able to blow and suck air through the hose fitting when I had the valve cover off.

I don't want to have my friend spend money on a part he doesn't need.

Is there a test I can do with a vacuum gauge that would help?

Thanks.

 

[boom10ful]

Excessive vacuum in the crankcase will cause the engine to run lean because it will be sucking unmetered air through any seal that it can like the rear main seal.

 

[Number_35]

Excessive vacuum in the crankcase will cause the engine to run lean because it will be sucking unmetered air through any seal that it can like the rear main seal.

That should set a code, correct?

 

[boom10ful]

That should set a code, correct?

It should but not always. Check with a scan tool and see your fuel trims. It should show lean if that's your problem.

 

[Number_35]

It should but not always. Check with a scan tool and see your fuel trims. It should show lean if that's your problem.

Thanks, will do.

 

[GMBoy]

I should have taken your advice; in trying to save my friend some money, I replaced only the VC gasket.

I've since done more research - there are a number of YouTube videos, and Sonic/Cruze forum threads out there, all indicating that the integrated PCV valve is fragile and fails frequently. There are discrete replacement units available, but it seems that most people are not successful in getting it to seal, so they wind up buying a new valve cover anyway.

I did blow and suck through the PCV tube when the VC was off, and noticed that there was airflow both ways. I'd assumed that rather than a valve it was just a port with a fixed restriction.

So, it appears the PCV membrane has failed. (The car has 125K km [ c. 78K miles] on it, and the folks online say these often fail between 60K and 80K miles.)

Given that it's failed open, what problems will that cause?

The engine does have some significant oil leaks, which would explain why it was down 2 - 2-1/2 litres, and I'm wondering whether the open PCV valve could be the cause. (I understand that if the PCV valve were blocked, the crankcase would be pressurized, and oil leaks would result, but I don't know whether an open valve would also cause oil leaks.)

Another thing is that the oil filler cap on the VC looks to be slightly concave, like there's suction happening.

My friend is going to bring the car over, and I'll do more investigation. He is discouraged about what he's already had to spend, and would like to avoid buying a new valve cover if possible.

Thoughts? Any Chevy 1.8 specialists out there? Thanks in advance.

Yes, that is a bad valve cover due to the failed PCV. You will have to replace it.

 

[Number_35]

Yes, that is a bad valve cover due to the failed PCV. You will have to replace it.

I don't suppose GM issued a recall for this -
it seems to be a poor design with a high failure rate

I wonder if anyone's put a conventional PCV valve inline with the hose from the VC to the IM?

 

[Number_35]

I'm going to replace the valve cover. RA has options - Apex, AutoTechnica, Dorman, SKP, and GM Genuine.

I know that Dorman does not have a good reputation. Don't know anything about Apex or AutoTechnica. I think SKP is OK, but am leaning towards just spending the extra and going with GM.

Thoughts, recommendations? Thanks!

 

[GMBoy]

I'm going to replace the valve cover. RA has options - Apex, AutoTechnica, Dorman, SKP, and GM Genuine.

I know that Dorman does not have a good reputation. Don't know anything about Apex or AutoTechnica. I think SKP is OK, but am leaning towards just spending the extra and going with GM.

Thoughts, recommendations? Thanks!

I have used the GM, Dorman and SKP without issues. The Dorman part is actually one of their "OEM FIX" items where they supposedly make improvements to the original design. I have installed about 7 or 8 of them without issue. I used an SKP once and it was good too.

 

[Number_35]

I have used the GM, Dorman and SKP without issues. The Dorman part is actually one of their "OEM FIX" items where they supposedly make improvements to the original design. I have installed about 7 or 8 of them without issue. I used an SKP once and it was good too.

Thanks, it's good to hear that the aftermarket units are good.

My friend chose to play it safe, and I've ordered the Genuine GM part. Due here Thursday, so we'll see.

 

[JoelB]

This car seems to be in pretty bad shape for 78k miles and 9 years. Doesn't make me feel great about my current daily driver