Can't get the oil filler cap off

[RuskiE39]

Woke up this morning and wife was telling me her car wouldent start, most likely the battery since it's really old and the battery light was flashing when she said she tried turning it over. But anyways, I decided to do a quick check and look at the oil and coolant, both were low... tried to un-screw the cap and it just keeps spinning and spinning... I don't know what to do and don't want to risk snapping the cap and dropping little plastic shards into the engine. Any ideas?

[Ed CT]

I suppose you could try wrapping some twine or stronger nylon thread counter-clockwise under the cap, and pull that when you turn the cap in hopes that the thread will turn the two prongs that hold the cap onto the VC. Last resort is to remove the valve cover itself.

EDIT: Is it sub-freezing where you are? Maybe it's frozen from crankcase moisture, and all you need is a heat gun or hair dryer.

[RuskiE39]

I suppose you could try wrapping some twine or stronger nylon thread counter-clockwise under the cap, and pull that when you turn the cap in hopes that the thread will turn the two prongs that hold the cap onto the VC. Last resort is to remove the valve cover itself.

EDIT: Is it sub-freezing where you are? Maybe it's frozen from crankcase moisture, and all you need is a heat gun or hair dryer.
Nope, it's quite warm.. about 50 degrees. I'm going to go play around with it and see what I can do... I can't even ever find this being an issue anywhere on google.

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Got it off!!

[Ed CT]

Nope, it's quite warm.. about 50 degrees. I'm going to go play around with it and see what I can do... I can't even ever find this being an issue anywhere on google.

I had one break on a '73 mustang - had to pick the two metal prongs out of the rocker assemblies!
Try the twine or string thing while pressing down on the cap to relieve the interference fit.

[philly98540]

Low on oil? Damn, I thought you had the flush that solved that one for you. Or have you put on a lot of miles?

Maybe all the checking and filling checking and filling finally made the cap fail. You may have exceeded the 10^6 rated open/close cycles. JK. How'd it fail?

[RuskiE39]

Well... this thread just turned into a DIY... guys, I would also recommend adding this to your list of maintenance items.

I ended up lightly tapping on the top of the cap with my palm to see if I could break any sludge or anything else forcing it in place. Somehow, I ended up cracking off a piece of the plastic cap at the very edge where I could see underneath where the main plastic/metal/o-ring where. After that, I could see a small groove under the plastic where I could stick the tip of a flat head screwdriver in to get leverage and twist the cap off. I ended up slipping and completely breaking the entire plastic cap off.

http://i59.tinypic.com/2a4vmrn.jpg

And so I was left with this:

http://i60.tinypic.com/rrpct1.jpg

I wasent sure what was under the plastic cap and my biggest fear was getting plastic shrapnel inside the motor from breaking it off. But not to worry, the underside from the plastic cap is completely sealed and you can twist off by hand from here.

http://i58.tinypic.com/2zp2ttx.jpg

Get this replaced guys! This is as bad as your hood cable snapping and leaving you stranded somewhere.

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Low on oil? Damn, I thought you had the flush that solved that one for you. Or have you put on a lot of miles?

Maybe all the checking and filling checking and filling finally made the cap fail. You may have exceeded the 10^6 rated open/close cycles. JK. How'd it fail?
http://res.cloudinary.com/urbandictionary/image/upload/a_exif,c_fit,h_200,w_200/v1404878212/s8k5gwvy8e3qkfnqbr5v.jpg

This is my wifes car. Do you even read? Lol jk. My E39 is almost at 3,000.... that's oil change time.

[philly98540]

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http://res.cloudinary.com/urbandictionary/image/upload/a_exif,c_fit,h_200,w_200/v1404878212/s8k5gwvy8e3qkfnqbr5v.jpg

This is my wifes car. Do you even read? Lol jk. My E39 is almost at 3,000.... that's oil change time.

Duhh. Shame face on...

[Ed CT]

So, looks like the top half wasn't turning the bottom half?
Glad to see there was no shrapnel into the engine, although I see you cut your thumb when you slipped - clean it out or you may end up with a grease tattoo (I have one!)

[RuskiE39]

So, looks like the top half wasn't turning the bottom half?
Glad to see there was no shrapnel into the engine, although I see you cut your thumb when you slipped - clean it out or you may end up with a grease tattoo (I have one!)

Haha, yeah I have plenty of "tattoos."

But that's basically right. It looks like under the plastic cap there are 4 slots that hold it on to the main part and they all look to have failed.

That's what those tiny little pieces on the cap are, those where the teeth that held it on.