# Oil filler cap ejection/oil eruption



## cruzin2012 (Jan 12, 2012)

Today coming to work I had to get into the turbo a bit to pass another driver. I usually don't get on the gas too much for better mileage. When I came to my next stop I smelled a fuel and oil burning smell. I thought it was the truck in front of me and continued the 1/4 mile or so to my work. When I parked and stopped the engine I found out it was my car :sad:... I opened the hood and there is oil spray and the oil filler cap is laying on top of the engine near the rear. There is a large 8" diameter spray of oil on the hood and oil covering various parts in the vicinity of the oil filler hole. Glad it didn't burst into flames.

I thought that maybe the cap was not closed tight and it just fell off but when I see the oil spray I think there was probably a good deal of pressure and maybe a loose cap. The cap is not cracked or broken.

PCV valve? Turbo seal? any ideas......

Contacted GM to have the car towed to the dealer which is only a couple miles away and will have them look at it tomorrow.

2012 Chevy Cruze Eco manual ~33,000 miles


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## Merc6 (Jun 8, 2013)

Did they recently change the oil?


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## cruzin2012 (Jan 12, 2012)

No. Over 6k miles since last change.


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## cruzin2012 (Jan 12, 2012)

No ECU codes. I am thinking that the last oil change the cap was left not fully tight and just finally popped off.


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## Robby (Mar 1, 2013)

The improperly secured cap has merit.....it is fairly easy to have only one of the two engagement legs, uh, engaged.

When you got on it for a moment the crankcase went to positive pressure and spit the cap (and lots of oil).

At least you caught it, creating a story rather than a fire......good catch.

Rob


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## Vetterin (Mar 27, 2011)

I would go with the loose oil cap also.....except it seems odd that you could drive 6000 miles without at least a leak around the cap.


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## blk88verde (Apr 30, 2011)

> I would go with the loose oil cap also.....except it seems odd that you could drive 6000 miles without at least a leak around the cap.


 If the oil cap were loose, I would expect a poorly running engine or Check Engine Light.


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## piccoj99 (Nov 3, 2015)

I have the same exact car and experienced the same exact problem this summer. I also have no reason to believe the cap was loose or ill-fitting. Did you have any subsequent problems? 3 months passed and then I started to get a rumble at idle. They replaced the pcv valve and it seemed to help. But then recently found oil leaking, presumably from the head gasket. To me, it's running pretty well. Took it in to a dealership but apparently they overbooked on the day I scheduled (today, btw). Now I'm trying to decide who I should take my business to because they have consistently let me down. Wondering if this car is going to do the same. I like the car quite a bit, but am definitely starting to get annoyed.


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## jblackburn (Apr 14, 2012)

piccoj99 said:


> I have the same exact car and experienced the same exact problem this summer. I also have no reason to believe the cap was loose or ill-fitting. Did you have any subsequent problems? 3 months passed and then I started to get a rumble at idle. They replaced the pcv valve and it seemed to help. But then recently found oil leaking, presumably from the head gasket. To me, it's running pretty well. Took it in to a dealership but apparently they overbooked on the day I scheduled (today, btw). Now I'm trying to decide who I should take my business to because they have consistently let me down. Wondering if this car is going to do the same. I like the car quite a bit, but am definitely starting to get annoyed.


Uh...valve cover gasket?


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## neile300c (Jul 8, 2014)

What's weird is we had a 2012 Sequoia come in for an oil change, the oil cap was sitting on the fender. The customer said they didn't go under the hood and notice, but there was no oil under the hood, and no oil missing on the dipstick. We even ran it, and the oil pressure light didn't even come on. It was 4000 miles, but almost a year since her last oil change.

But, if the threads are not stripped on the cap, it obviously it screwed off, or was loose where it could come off.


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## Robby (Mar 1, 2013)

neile300c said:


> What's weird is we had a 2012 Sequoia come in for an oil change, the oil cap was sitting on the fender. The customer said they didn't go under the hood and notice, but there was no oil under the hood, and no oil missing on the dipstick. We even ran it, and the oil pressure light didn't even come on. It was 4000 miles, but almost a year since her last oil change.
> 
> But, if the threads are not stripped on the cap, it obviously it screwed off, or was loose where it could come off.


In general, V-8's and V-6's will not throw oil from the oil fill.
This is because, as long as the PCV is working, the positive/negative crankcase pressure moments are very low.....more cylinders make for a more even blow by pulse.

Engines of four or less cylinders have dramatic crankcase pressure changes....in the case of a 4 cyl, 2 rising while two pistons dropping...one of which adds a bit of blowby to the equasion.....in addition to this, on the Cruze, a pressure fedcamshaft is directly under the oil fill cap so with the cap off it just heaves oil out the fill hole.

This may be why they started using a baffled oil fill tube beginning sometime in 14......the cap doesn't have to act as a splash shield and potental leak point.

Rob


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## JustinA2012! (Nov 5, 2017)

I?ve got the same issue? Same car but the RS model. Was it a loose cap that was decided? What could cause such high oil pressure?


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## Robby (Mar 1, 2013)

JustinA2012! said:


> I?ve got the same issue? Same car but the RS model. Was it a loose cap that was decided? What could cause such high oil pressure?


I believe it ended up that the cap was incorrectly seated. A fairly easy thing to do on the pre baffled fill caps.......not a high pressure issue, but there is a large volume of oil thrown off the camshafts and it'll get pushed out of any seam it can find.

Remove/re install the cap......look carefully that is level with the cover.......clean up the mess it makes.

Rob


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## Jarhead (May 9, 2021)

Robby said:


> I believe it ended up that the cap was incorrectly seated. A fairly easy thing to do on the pre baffled fill caps.......not a high pressure issue, but there is a large volume of oil thrown off the camshafts and it'll get pushed out of any seam it can find.
> 
> Remove/re install the cap......look carefully that is level with the cover.......clean up the mess it makes.
> 
> Rob


Hate to admit it but evidently I didn’t put the cap on properly and resulted in the cap blowing off and oil spewing all over.
I changed the valve cover a couple days due to the diaphragm issue/CEL. Along with the valve cover was a new oil cap “O” ring. I dutifully changed it out as well. The new O ring is stiffer and my guess is changed the feel of installing the cap. Found the cap in the engine bay and took my Time reinstalling . Lesson learned😊


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## jblackburn (Apr 14, 2012)

Jarhead said:


> Hate to admit it but evidently I didn’t put the cap on properly and resulted in the cap blowing off and oil spewing all over.
> I changed the valve cover a couple days due to the diaphragm issue/CEL. Along with the valve cover was a new oil cap “O” ring. I dutifully changed it out as well. The new O ring is stiffer and my guess is changed the feel of installing the cap. Found the cap in the engine bay and took my Time reinstalling . Lesson learned😊


They redesigned the whole oil cap because this was so common. So it’s not just you that has made the mistake. The updated cap is much taller and easier to tell when it’s actually installed correctly.


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