E60I

Hi guys,

I am probably the first guy to replace the oil filler cap on an E60. I did a search by topic/thread and even googled it (not trying hard enough?).

To be specific, my car is a '06 BMW 530i. The ring around the oil filler cap (see attachment) is made of "hard plastic". I tried lifting/twisting motion while turning it counter clock wise; and that did not work. I resorted with a flat screw driver, pried it out and broke a small piece of that "hard plastic" ring. May I get some suggestions on how to properly install the new oil filler cap without breaking it?

Thank you in advance for your help!

Boland01

I beleive on my 2010 535 all you need to do is take the engine cover off- 4 bolts. With that removed you should be able to ust lift off the oil fill cap assembly. Assuming it's the same as mine.

BimmerFan52

Not sure I understand the question. Are you trying to replace a portion of the cap, or trying to learn how to install and remove the cap without breaking it? Sorry in advance if I misunderstand.

If it is the latter, the cap will engage with the valve cover when the two metal tabs on the cap engage with the cutouts in the hole in the valve cover. Ideally the cap should lock with the lettering on the cap readable while standing in front of the engine. To install, hold the lettering so it is straight and readable (call it the 12 oclock position). Then rotate the lettering counter-clockwise about 135 degrees or so the lettering instead of being straight up at 12 oclock is now about 7:30 on an imaginary clock, and the tabs on the cap will pass through the cutouts in the valve cover hole and the cap will drop right in and engage with the valve cover. Then rotate it clockwise back to the 12 oclock position to lock it.

I find that my cap after a few thousand miles almost becomes frozen and can be very difficult to remove with one hand. I end up having to put pressure with both thumbs in two opposite corners of the cap, forcing it to rotate counter-clockwise to break it loose to remove it.

E60I

Guys,

Thank you for the help!

Sorry, if my descriptions are not clear!

I want to remove the old oil filler cap and install a new one in. I will follow BimmerFan's instructions and report back later.

Just curious, is it even possible for the oil filler cap to leak oil?

Thanks!

BimmerFan52

It is unlikely that the cap would leak oil as the oil is not pressurized within the valve cover.

But if the cap seal against the valve cover is defective it can allow outside air to "leak" into the valve cover, which is a problem. During idle the intake system is at a pressure lower than the outside atmosphere in order to draw air into the engine. All of the air should pass through the air intake duct system and across the Mass Air Flow Sensor (MAF), which carefully measures the volume of air and sends this information to the computer to enable it to meter fuel to keep the ratio of fuel to air precise.

If there is any leak in the system after the MAF which would allow extra air to enter the engine, then the fuel/air ratio is thrown off which can cause the engine to run roughly (the actual ratio is low on fuel because extra air was added without the MAF knowing it and is referred to as a "lean" mixture). This leak of air is commonly referred to as a vacuum leak.

To test the effect of a very bad vacuum leak, while your engine is idling, loosen and slightly lift the oil filler cap momentarily (be ready to replace it quickly). The engine should stumble and almost die. Loosening the cap replicates a huge vacuum leak, but even a small one at the edge seal of the oil filler cap can cause rough idling.

Unfortunately, most vacuum leaks are tiny tears or pinholes in rubber diaphragms and seals elsewhere on the engine and can be real nightmares to locate and repair.

E60I

BimmerFan52 or anyone,

I think a faulty/leaking oil filler cap is causing my engine to shake. Can someone please give me easier instructions on how to remove and replace it?

If I was to stand on the driver's side of the engine and facing forward, the "BMW" letters of the filler cap would be facing me in an upright and closed position. What do I need to do to remove and replace it? Does the oil cap have to be in the open or closed position when I turn it a certain way to remove and install it?

Thank you in advance for your help!

Redtwin

I am still trying to understand why the valve cover would be under vacuum. It isn't part of the intake system and if valve stem seals were so bad that they were allowing the pistons to suck air in from the valve cover (thereby creating vaccum), you would have an impressive smoke screen out the exhaust.

If removing the oil filler cap cause a change to the engine idle, that is indicative of a faulty crankcase ventilation system which would result in a pressurized valve cover. If the valve cover became pressurized this could cause oil to be pushed past the oil filler cap and valve cover gasket.

If you are finding lots of oil around your oil filler cap, the issue could be due to the CCV system rather than just the oil seal itself. I mean, you could just replace the seal in the oil cap, but the cause of the seal failing would still be there and the oil /pressure will find it's way out somewhere else...probably past seals that are more difficult and costly to repair.

E60I

The oil indicator in i-Drive shows the level to be a bit above the MAX line. Can overfill cause the oil leak out of the oil filler cap?

Engine idles smooth but feels rougher when I shift to either R or D (drive). Oil separator and hoses were replaced a few weeks ago.

Still, I would like to know how to replace the oil filer cap to see the result. I read somewhere that the car can run rough if the oil cap is not properly sealed.

BimmerFan52

Pull your oil filler cap off while the engine is running to see the results.

E60I

Successful Technique: Turn oil filler cap counter-clockwise until it stops. Then, lift.


Results after new oil cap replacement:


-Car shows a huge improvement! It idles a lot smoother.


-No more sluggishness or lack of power on acceleration.


Thanks!