Why would a cam shaft plug pop out?

Alright, I am very certain that the cause of the mess of the oil spraying over my engine has to do with the Cam Shaft Plug. The one that is missing is above the oil pump on the passengers side, here: I did not notice that it was missing as I am still new to owning the car ( See here) and I needed to drive it right away to Minneapolis as I had military drill weekend this weekend. I initially thought that the suspect was here: and I was able to remove clean and seal (the o-ring on it was barely doing its job) and secure in place. After driving back from Minneapolis, I noticed that there was still oil leaking and it was not until today, after more research and looking at various picture of the M96 engine did I see that I was missing the green plug entirely. My question is, what would make this pop out? I have a plug on order and I look forward to just popping it in and calling it a day, but we all know that it is never just that easy. Are there vacuum issues that I should look out for? The oil cap comes off fine at idle, so I am certain that it is not the AOS. I do get a check engine light, OBDII code P0507, which equated to 'Idle Air Control Higher Then Expected'. The engine seems to idle fine, however. Any insight will be appreciated. I have owned the car less then a week, and though I enjoy working on the car, I would really just like to get on the road and have a nice drive and enjoy the weather. Thanks. DC Josh

Usually caused by excessive sealant on the top of a camcover "sealing" a oil passage & causing the pressure overload. Thankyou for your military service!

They can be slightly difficult to seat without a good rap with a piece of wood. Maybe somebody did an XXX R&R and didn't seat it properly? Probably no big thing. Pop another in there.

Those are positive reply's, and are about in line with what I have looked into. The car was transported on a trailer from California last week. I am suspecting the angle which the car was pitched may have caused for excessive oil drain toward the 'back' of the engine, causing pressure upon start up and popping it out. This theory is based on no knowledge, just a gut instinct. Again, any other insight is appreciated. DC Josh

Get a visual on the other cam plugs to see if they are installed flush. It's difficult to remove them if they are. Also look for sealant around the cam cover edges.

I just had all of them taken out for the IMS job. They are not at all easy to pop out, they are pretty snug against the casing. Is there a possibility that somebody didn't put a new one back in after some work done on the car? IMS, or anything that required locking the cams on the particular bank?

Replace the plug and keep an eye on it. Maybe it was just a bad plug - but if it pops out again, start reading up on the threads others have posted about this. Byprodriver's comment - excessive sealant causing a pressure spike - appears in a few other threads I've read about this...

There is another reason the green plug(s) come out. If the steel plug in the cam has come out/is leaking it will pressurize the area between the cam end and the green plug, popping it out with force. If that happened you would have dumped quarts of oil in a very short time.

Alright, round three of this mystery. I ordered the green plug based off of the pictures that I had seen of the M96 engine. It turns out that I need the OEM brown plug or aftermarket black plug: Found Here The brown plug is a little larger and there are only two per engine. Sooooo, I am back to where I started, a little wiser. But the part will be here tomorrow from Pelican and I am hoping that this will not just 'pop' out again.

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Frank, I am certainly not dumping quarts of oil out; it is very much a mist and it does accumulate and then drip onto the exhaust making a mess and causing smoke. I am just hoping that there is not a vacuum or pressure related issue that I need to address, otherwise, I will be looking at this problem again in the future.

The Cam Plug came from Pelican Parts today. I went to the lift at school and installed the plug as well as cleaned up as much of the oily mess as I could. Attached is the culprit. That $10 plug caused me a lot of worry and grief. I'm just glad I was able to figure it out. So far, it is holding, but I will be keeping an eye out on it to see if it 'pops' its way out again. DC Josh

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my steel cam plug and green plug cam out. How do I fix this and can I fix it with the cam in the motor?

I would recommend dropping the engine - at the very least, you can drop it 6-8", but it'll be much easier with the engine all the way out. I think I've read that some people thread the cam end plugs...

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If the expansion plug in the end of the cam came out you will have to drop the engine and pull out the cam. This happened to me years ago when I was fixing my intermix and used a home made tool to hold the cams in place and it deformed the expansion plug. When it popped out the green plug was forced out and oil spewed from the engine. It would have emptied the engine of oil very quickly! I searched and searched and could not tine the exact fit expansion plug. I ended up taking all four cams out, taking them to a machine shop and have the ends of the cams threaded and installed threaded steel plugs with Loctite to hold them in place. By the way this is one of the "modes of failure" that Flat Six lists and they do this on all their engines. They also replace many of the other expansion plugs on the engine.

The big brown cam seals have been know to pop out on the 3.6 engine if the driver lays on the rev limiter too long. There is a positive crankcase pressure that will start to pulse and can become strong enough to pop out the seal. Just stay off the rev limiter and it should be fine, if not you need to have the crankcase pressure/blow-by checked..