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GENERAL MOTORS DOES NOT CARE ABOUT MY HEALTH
Gina, unfortunately it would seem that your service manager doesn't care about you. That doesn't mean GM doesn't care about what's going on. I can imagine how frustrated you are, but as others have suggested you need to switch things up a little, try another dealership or talk to someone else at your dealership. If that fails start a Lemon Law claim process. Call GM directly, but don't expect to talk to the CEO.

There's a Gm Customer Service rep on this board named Stacy, get her involved, give her your dealership info and plead your case with her.

In the short term try to identify what things seems to make the problem with your car worse. If you're always driving at really high speeds when this happens, try slowing down and/or taking a different route. Try turning the recirculation function from "frsh air" to "recirculated air" and open a window. Try different things to keep the car from venting fumes into the cabin. If nothing works stop driving the car! It's not worth your health.

Good luck and keep us posted!
 

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I returned there today and told them to fix the problem, then return my car. They found coolant leaking through the threads of one water pump mounting bolt. A new water pump was installed under warranty and all is good.
Today? I hope all is well, but I'd feel more confident after a few days of driving the car to be sure the problem doesn't come back. It would seem the root of the problem for most people is not a leaky water pump bolt.
 

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It's a known issue with the water pump. The replacement solves the problem.
I stand corrected! I was not aware... is this one of the failure modes for people with the coolant smell inside the car?

I may look at this on my car; my overflow is a little low, I can't see any leaks anywhere and I have never experienced the smell inside the car. If it hadn't been for the coolant smell threads popping up I may not have even looked at my coolant level until the spring!

Regarding the VIN cutoff, do we have any information regarding the builds that are affected?
 

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Thanks for your support, sounds just like what I get from General Motors.
OK Gina, no need to get upset with us. This is a free internet forum full of very helpful people. If you come here with a problem and get anything positive at all out of it you are ahead and it didn't cost you anything but your time. If you get nothing out of it it didn't cost you anything but your time. Even if we DID know what was wrong with your car and how to fix it, there's nothing we could do about it... you are still at the mercy of your local dealership and/or anyone you can get on the phone at GM.

This is also the internet - you need to know how to filter the information you receive to get out of it what you need. Growing a thicker skin is also a good idea as not everybody will immediately offer you a shoulder to cry on. Learn to ignore the stuff that doesn't help and focus on the stuff that does.

Having said that, we do not know the cause of this problem. Anyone on this forum who is experiencing the same issue you are is in the same boat you are. Some people have done some research and negotiated their way into having GM buy back the car. If your health and well being is at much at risk as you say it is, this should be something you are researching yourself. We are not Lemon Law lawyers.

You can be assured if there is any progress with this issue you will find out about it on this forum. This could be very helpful in dealing with your local dealer to have the issue fixed if it comes in the form of a TSB (Technical Service Bulletin) or recall notice.

Please be patient and take this forum for what it is; a bunch of regular people, most of whom own a Cruze, some of whom have the same issue you do, and none of whom can (at this moment) help you out of your situation.

I wish you all the best and I hope you let us know if you make any progress in dealing with the issue. It is that type of contribution that is most valuable to others on forums like this.
 

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I have a question… perhaps this has been covered already, perhaps not.

When the coolant level is getting low is the dealership replacing the missing coolant with more 50/50 coolant/water mixture, or are they just topping it off with water? Is the coolant concentration being checked after several top ups?

Why I'm asking; hot pressurized coolant leaks, hot pressurized water evaporates.

A car that has had its cooling system topped up several times with a 50/50 mix should test one of two ways: Either the coolant/water ratio is still good (indicating a leak), or the ratio is skewed with too much coolant (indicating water vapour loss). Everything I'm reading so far suggests the latter, and the fact that GM has devised an interim "fix" involving a modification to the vapour vent on the overflow tank seems to confirm it.

So now my wheels start turning.

The cooling system is a closed circuit designed to operate at a certain temperature and pressure. Operating temperatures should result in operating pressures somewhere below the maximum set by the overflow tank cap pressure. If the pressure exceeds the cap set pressure the system vents, causing the coolant smell everyone is complaining about.

Something is causing the pressure in the system to increase beyond the designed operating pressure. That something is most likely coolant boiling. Localized coolant boiling causes vapour and pressure increases within the system, the vapour builds and must be vented.

This car has a turbocharger. This will be important after my next paragraph.

Cruzex pointed something out that I was not aware of, and that was the car's electronic thermostat being programmed to regulate coolant temperature above 220F in certain circumstances (I knew the Cruze ran hotter than some, but I didn't know it was that hot). The hotter the coolant is the closer it is to its boiling point, so the less cooling ability it has (ability to absorb heat from hotter engine parts) before it boils.

Back to the turbocharger. It is an exhaust driven air pump that is cooled by both oil and coolant, exhaust driven being the key word here. The coolant going to the turbocharger and oil cooler comes from the top forward facing port of the coolant outlet on the driver's side of the cylinder head. This is the smaller of the two ports, the larger one on the bottom feeds hot coolant to the radiator (the rear port feeds hot coolant to the heater core and the tube coming vertically off the top allows vapour to travel directly to the top of the overflow).

The coolant going to the turbo has already passed through the engine and is hot. The turbocharger is being heated by exhaust gasses and is cooled by the already hot coolant going to it (as well as the engine oil being supplied to its bearings). This, as far as I know, is similar to the plumbing on most turbocharged vehicles. BUT, the Cruze operates at higher coolant temperatures than most engines I know of. At highway speeds the turbocharger is getting a lot of heat from the exhaust

If the flow of coolant through the turbo is not sufficient it is possible that the coolant is vaporizing when it gets into the hot turbocharger. This would cause vapour through localized boiling of the coolant, and would increase coolant system pressure to the point of venting vapours from the overflow tank.

If this is in fact the problem, the only way to solve it would be:

1. Increase coolant flow through the turbo
2. Increase oil flow through the turbo
3. Decrease the operating temperature of the engine coolant.

1 and 2 seem doable, but I'm not sure what it would take, maybe a plumbing change is all? If there is any kind of restrictor in the coolant line to limit the feed of coolant this could be easily changed. There is a TSB regarding restricted or reduced oil flow to the turbocharger, so this could have something to do with it (339359 and 339360 read the same):

Service Bulletin 339360 for Chevrolet ENGINE AND ENGINE COOLING | AutoMD

I would suggest a good starting point for anyone with this issue contact their dealer and ask if one of these two TSBs applies to their car. If it doesn't I might push harder and ask that they check it out anyway… reduced oil flow to the turbo could cause the turbo to run hot, boiling coolant or causing damage to the turbo's bearings.

3 would have implications with mileage, so I doubt that would be an option as it would require TONS of re-certification even if the numbers ended up coming out the same. Also, a reduction in coolant temperature would have to be pretty drastic to cure a problem like this… I doubt dropping the coolant temperature 5-10 degrees would eliminate this kind of issue.

I'm not sure what's going on inside this little powerplant, but the signs lead to coolant boiling somewhere and my finger would point first to the turbo.
 

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There's actually a software update that is supposed to cool off the turbocharger with the engine fan once the engine is shut off... ...This software package also has other benefits to it (like improved acceleration smoothness when the engine is cold). I should be having it done to my car soon, and I will fill the tank back to the proper level and see if it makes any difference whatsoever.
Please let us know more about this update! If you can get a TSB # from your dealer and any kind of indication which years/builds of cars are affected that would be GREAT!
 

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I still believe the crux of the problem is that the ECM and its software can't manage the temperature properly. I believe that this design was targeting maximizing gas mileage and lowering emissions. The side effect is that the motor just gets too hot at times. It depends on the driving environment and the engineers weren't able to predict (or test) all possible combinations of inputs. If that is true, they may take a very, very long time to come up with a fix for this design.
Well, it would seem so far that most of the people experiencing this issue are simply driving down the highway with the heat on... I would have thought that scenrio was well covered in their development! :)
 

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Well, everything I posted regarding the cause of the problem was based on gut feelings and poor on-line parts assembly drawings, so I went out and took a little deeper look. I pulled the heat shield off the manifold/turbo to get a better feeling for what's going on down there.

The hot coolant outlet on the driver's side of the cylinder head has several ports on it, as can be seen in this picture:
Auto part Engine Fuel line Vehicle Car

The hose going straight up is the vent tube alowing vapours back to the overflow, the forward facing port below that is the coolant feed for the oil cooler and turbo (the one I'm interested in), and the large hose below that is the hot coolant supply to the rad.

Looking a little lower:
Auto part Engine Vehicle Automotive engine part Fuel line

Here you can see the coolant feed line divide; the thick steel line goes down and back to the oil cooler, and a smaller line tees off of that. It's a rubber hose with expanded aluminum heat shielding pulled over it, and right where the shielding ends it changes from a rubber hose to a steel line. This is the coolant line to the turbo. If you look just below the turbo's coolant line you will see a small diameter steel line coming out of the oil filter/cooler assembly; this is the oil feed line to the turbo. Both lines pass underneath the manifold and bend forward to feed the turbo. The oil feed attaches to the top of the turbo center section, it's the large round silver bolt. Just visible down behind the turbo's center section is the coolant feed, it's the silver hex-looking thing just to the left of the oil feed.

Another view:
Auto part Engine Fuel line Vehicle Automotive engine part

The rust-colored metal piece between the manifold and compressor housing is the center section of the turbo where the bearings are, and where the oil and coolant feed for cooling. Seeing how close everything is packaged with the exhaust drives home how important cooling is in these components. The turbo has oil film bearings that would get cooked if it weren't for the coolant feed.

So after looking at all this, the oil and coolant lines are both steel and are both not shielded from the radiant heat of the exhaust manifold which they pass relatively close to. In the case of the oil line, it is my understanding that many turbos use a restrictor to limit oil flow, so the flow of oil to the turbo could be happening at a fairly slow rate which would mean the oil spending more time in the steel line and potentially heating up before getting to the turbo.

The same can be said for the coolant line, but I imagine the flow rate of coolant through the line would keep heat absorbtion from the manifold relatively low (but I have no way of knowing what the flow rate actually is).

One thing I can tell you for sure is that when the engine gets to it's targeted operating temperature the coolant flow rate through the turbo will be reduced. This is because flow through the turbo is dependant on the pressure difference between the suction side of the water pump and the hot side coolant outlet. When the thermostat opens the suction side of the pump can feed from the radiator, and the high pressure coolant in the outlet is allowed to flow through the upper rad hose to the radiator (and the radiator is a large low-restriction flow path). This reduces the pressure difference across the turbo's coolant circuit, reducing the amount of flow through both the turbo and the oil cooler.

All of this so far seems to feed my theory of coolant boiling in the turbo, and would explain why the coolant vapour smell only happens after driving the car for an extended period - long enough to get the engine to its operating temperature and get the thermostat open.

Having said all that, please remember that this is JUST A THEORY. In no way have I proven anything here, all I'm doing is trying to figure this out. Also, I'm fairly certain that most turbocharged cars are plumbed in a similar fashion, though every engine will have its own characteristics. If I am onto something it may explain why it is taking a while for GM to come up with a fix.

Another thing that went through my mind was the actual issue of the smell in the car and how it gets there. I've read several reports of people having their heater core replaced and the problem remaining. I remember reading somewhere that there was an admission by GM that "porous" materials in some heater cores were being blamed even though there was no leaking coolant evident. Air can pass though materials that liquids can't simply because it is made up of smaller molecules. If there is vapour circulating in the cooling system, it is possible that the vapour could escape through a porous material without any coolant leaking through. Just a thought... and if this is indeed part of the problem it adds a whole other dimension to the issue and makes solving the problem that much more complicated for GM: they will be tracking two different problems with similar symptoms.

I don't know if this information will actually end up being useful or not, but it would seem that adding a small radiator or even an auxilliary pump (or both) to the turbo's coolant line could help to cure this, IF COOLANT BOILING IN THE TURBO IS THE ISSUE IN THE FIRST PLACE. Remember, I'm just posting information that may or may not have anything to do with this problem.
 

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It would appear that my '12 Eco (built in May '12) is not immune to this issue. While I was poking around under the hood I noticed my coolant is actually quite low, and there is lots of evidence of coolant vapour escaping through the vent on the overflow tank.

Note the crusty orange-ish deposits around the vent:
Auto part Automotive exterior Bumper


And the low coolant level (fill arrow is on the corner of the tank):
Auto part Engine Vehicle


This means I now have a direct interest in this issue! And here I thought I was just curious for the sake of others! :)

My daily commute is EXTREMELY easy on the car, so easy in fact that when it is as cold as it has been for the last month or so I doubt I'm even getting the engine to the operating temperature where the thermostat opens. HOWEVER, I was on the highway about two weeks ago with the cruise control set at 100 km/h (62 MPH) for about an hour each way, and I remember smelling something and thinking it smelled like burning plastic, but it was a very faint smell. Until I read all the reports of the same type of smell (in addition to the coolant smell) I never thought anything of it after checking under the hood to make sure nothing was actually burning of course.

For the record, I have yet to smell any coolant. At home I park outside, and at work I'm in a large-ish underground parking garage, so I wouldn't have a chance to smell any coolant vapours built up around the car. I have not smelled coolant in the car either. It will be interesting if this issue still looms in a few months when the weather warms up here... will I be choking on coolant fumes also? Am I a lucky customer with a good (non-porous) heater core? Did I just jinx myself?

I'm really curious as to two seemingly common symptoms regarding this issue:

1. Cars seem unaffected until some time/mileage passes.
2. Burning plastic smell... what the heck is it? (maybe a rubber coolant line cooking and becoming restrictive? WILD guess!)

I'm going WAY out on a limb here so take this with a grain (or bag) of salt, but it almost seems like some plastic/rubber component goes through a heat related change (burning smell) after which the coolant vapour issues start. Does anyone with the problem have a different story than that? So far from what I've read it seems to be a fairly consistent chain of events. The plot thickens...
 

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CHEVROLET: THE OIL FEED PIPE NEEDS CHECKING AND REPLACED. IF RESTRICTED, AND TURBOCHARGER ASSEMBLY SHOULD BE REMOVED AND REPLACED, AND THE ECM SHOULD BE VERIFIED FOR LATEST CALIBRATION TO ALLOW TURBOCHARGE TO COOL, TO REDUCE LIKELIHOOD OF OIL COKING OIL FEED PIPE. MODELS 2011-2012 CRUZE, SONIC.
Finally the whole text! Thanks!

Well, oil coking has been a problem with turbos since the beginning of time (turbo time, anyway). I seriously wonder if the two issues are related? I also wonder if replacing the turbo is necessary for the obvious reason (coked bearings and feed lines), as well as maybe changes to the coolant plumbing??? Hmm...
 

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More "progress" with investigating this issue.

I went out at lunchtime at work yesterday to run an errand and left the heater control set to full cold the whole time to get the car nice and hot. It was snowing quite heavily yesterday also, so pushing the car around through deep snow is extra work for this little engine and gets it heated up real quick. When I got back into my underground parking I sniffed around the edge of the hood and could smell coolant.

So on my way home from work yesterday for the last 10 minutes of my drive I set the heater to full cold again to get the car as hot as possible. I pulled into the garage and shut the car off, immediately popped the hood and recorded this video (you might have to turn up the volume a bit to hear it properly):

Boiling Coolant 2 - YouTube

Low and behold, beneath all of the popping and creaking of cooling metal parts (which is normal by the way) you can hear the sound of air bubbles making their way through the turbo/oil cooler coolant feed line. This means there IS localized boiling of coolant in either the turbo or oil cooler, and I'd put my money on the turbo being the culprit.

NOW BEFORE WE JUMP TO ANY CONCLUSIONS, all I've shown here is that there's enough residual heat in the turbo after shutting the engine off to boil the coolant inside of it. Whether or not the turbo actually boils coolant while the engine is running is another question I'm not sure I'll be able to answer, but I will offer this information. I was driving the car very easily at low speeds (without the heater going) on clear plowed roads prior to parking it in the garage, and was doing so in -12C (10F) weather. When I opened the hood there was a very faint smell of coolant, not strong at all but it was there. I could not detect any vapour escaping from the vent on the overflow tank. I would guess that someone blasting down the interstate at 80 MPH on a 100F day would be introducing thermal loads far greater than what I have done here.

Whether the Oil Feed TSB discussed above has anything to do with this issue I don't know, but it certainly seems like the two could be related (reducing either oil or coolant flow to the turbo will cause it to heat up more). It would be interesting to see someone with the coolant vapour problem have the TSB done and report back their findings. I will be contacting my dealership to see if the TSB applies to my car, and if it does I will try to get them to show me the whole TSB so I can understand exactly what is going on with the fix and what it does and does not address. If the turbo is boiling off the coolant in it after the engine shuts down, the turbo's center section could be getting hot enough to "coke" oil in the bearings and feed lines.
 

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I have a 2013 eco mt on order, and this thread is really causing me to pause.
I agree with XR. I wouldn't let a "potential" issue like this influence a buying decision. Any issue such as this will definitely have a fix coming, and it now looks like there may be two issues in play here, the most severe of which (coolant smell inside the car) appears to have been solved in the other thread. Sure it's only a one car sample at this point, but there is some very convincing information there and it sounds like it could be a legitimate solution. Also keep in mind how many hundreds of thousands of Cruzes there are running around. Not everyone has these issues.

I just got my '12 Eco MT in July last summer and I'm loving it so far. I'm sure you'll love yours too.
 

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OK, so I've done some reading. I Googled "turbo coolant boiling" and found lots of people claiming that coolant boiling inside the turbo is normal after shutting the car off. The hot turbo will cause the hotter coolant to rise and cause thermosiphoning (hot coolant rising flow) similar to the way a tank circulation block heater works.

What I still don't know is whether this boiling is enough to cause the pressure in the system to exceed the cap relief pressure and vent vapours. I also don't know if there's coolant boiling inside the turbo while the engine is running and there's coolant flow through the turbo. I would assume no, but there's that TSB thing that still needs to be looked into.

Does anyone feel like putting a camera under the hood of their car to record the venting of coolant vapours from the overflow? :)
 

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I thought adding coolant addressed that boiling coolant sucking sound.
I haven't topped off my coolant yet, it is still a little low. I'm planning to pick up some distilled water tonight and top it up.

With the reservoir at a higher level, the system pressure should be higher since there is less air to compress. It is possible that the higher pressure could raise the boiling point of the coolant slightly, which could reduce coolant boiling in the turbo. I don't think it would eliminate it, but it could reduce it.

Another thought is that maybe the coolant level drops (venting after shut-off) until the volume of air in the overflow is great enough to allow the turbo to boil coolant without pushing the system pressure above the cap relief pressure. Hmmm... I will have to check this out. Every time I've shut the car off and checked for venting I haven't seen it happening, but my reservoir level was already low. If I top off the reservoir and the venting starts after shut-off, this could be it.

I can smell coolant when I pop the hood even with the engine running, but the smell does not seem to be coming from the overflow. It seems to come from the hot water outlet from the cylinder head area, since putting my nose down around the vent tube to the overflow seems to get the most potent smell, but that said the smell is still pretty slight, not strong at all. My coolant level has not appeared to drop since I started checking it.
 

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Smell locations can be quite misleading in a hot engine bay. Just saying.
Yep - I'm being really general. When I put my nose right up to the vent on the overflow I can't smell anything, but hovering my nose around the small coolant tube that runs from the hot water outlet to the overflow reveals a very slight coolant-like smell. This is generally over the hot water outlet on the side of the cylinder head where four hoses and a coolant temp sensor all hook into the outlet, and the outlet itself mounts and seals to the cylinder head. Lots of potential there for a leaky joint, but I won't get worried about it until I get a closer look down there.

For all I know what I'm smelling could be the smell of the coolant seeping through the rubber hose... it's very faint, but is only noticeable in that area.

Also, I'm not too sure if the coolant is actually boiling. You can achieve a pretty effective thermal siphon without reaching boiling temperatures, which by the way are very high for antifreeze/coolant.
Did you get a chance to see the video I posted? In the video you can clearly hear bubbles travelling through the turbo's coolant supply line. What you can't hear in the video is the low rumbling "hiss" of the coolant boiling inside the turbo. It sounds kinda like a block heater.

The next time you drive your car, turn the heat off several minutes before getting to your destination to get her nice and hot, turn off the ignition, pop the hood and stick your head down by the manifold. Within about 30 seconds or so from turning off the engine you'll hear a noise similar to a kid trying to slurp the last few drops of his drink out of the bottom of the glass with a straw. Then listen closer, beyond all the clicking and popping of cooling metal, and you'll hear the boiling coolant in the turbo. You'll need to be in a quiet environment to hear this, I didn't notice it until I listened in my garage with the door closed.

I did a quick Google search on this and it seems to be quite common in turbocharged vehicles. Yes, the boiling point of coolant is quite high (~265F), but the temperature of exhaust parts is much higher than that. Once the heat soaks in the coolant will boil.
 

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Dropping the coolant level to the bottom of the arrow seems to have stopped the venting through the cap/tube for me. When it was higher, there was constantly a coolant smell any time it got up to temp from the teens - 40F.
Well, this would back up my theory. I'm going to do a little experimenting. My coolant is low, but for all I know the level dropped quickly when I bought the car and hasn't moved in a while. I will post my findings.
 

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My Cruze was delivered new with coolant in the reservior tank just covering the outlet hose on the bottom of the reservior tank...

...However others have gotten original GM cap replacements and have seen similar issues reoccur.
I'm one of them... both of my Saturns and my Corvette used the same type of tank cap, and I've had to replace them on both cars. In both situations they allowed water vapour to escape, letting the system go low. The 'Vette went low enough that air got into the system, the pump cavitated and the car started overheating on me on the highway.

EDIT: I haven't checked, but it's possible the Cruze still uses the same cap design? I'll have to look when the 'Vette comes out fo rthe summer... I hope not!

Interesting about the coolant level on delivery. Mine is a '12 also, and I never thought to look at the coolant level when it was new. When was yours built?
 

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I thought twice about it. I'm waiting here to see what the resolution of the issue is before I plunge in with a purchase. I don't need a $20,000 headache.
Seeing what other people have posted recently about their cars being low on coolant at delivery makes me think GM has done this intentionally to avoid this issue. As jblackburn pointed out, in his case the coolant level was low on delivery and he didn't experience any coolant odors until filling the overflow beyond that level.

I have not experienced ANY coolant smell inside my car at all. The only time I smell any coolant is if I pop the hood right after driving and stick my nose down near the hoses. That isn't a problem in my book. Though I CAN see evidence of vapour escaping the vent on the overflow bottle, that would be considered "normal" as that's why the vent is there. I am interested in this "issue" purely from a geeky Engineering point of view... I love looking into things and figuring them out, as in I like to know what's going on and exactly WHY things happen the way they do.

I bought some distilled water last night and plan to top up the reservoir to the cold fill mark after work today. If my car starts venting coolant when topped off but stops again after the coolant level drops, I would say that's a pretty good indication that this issue is under control. At that point it would just be a matter of GM letting people know that the coolant "fill" level had been revised.

We should be really close to hearing feedback about what appears to be the main cause of the "coolant" smell inside the car, which appears right now to be simply a few cars built with either too much grease on parts of the heater core vent module, or just some grease in the wrong place. Regarding odors from teh overflow tank venting, if GM has intentionally reduced the coolant fill level to resolve this, all new car builds should be without this issue and any cars built before this fix came into effect will have a temporary venting issue that will pass as soon as enough water vapour escapes and the coolant level drops in the tank.

If my mother needed a new car tomorrow I wouldn't hesitate to recommend a Cruze. It has been a great car for the 8 months I've owned it, I am VERY happy so far.
 
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