What can force oil out of the filler cap? - The Unofficial BMW M5 Messageboard (m5board.com)

nlk10010 · 5th September 2003, 20:25

So I brought my M5 in to Rallye yesterday morning so that they could take the next step in trying to solve the problem of engine oil seeping out of the filler cap. Apparently, BMW told them to replace the entire valve cover as well as, I presume, the cap.

OK. Well, after you change a few caps and it doesn't work I guess that's a reasonable thing to do. So the SA says the work load seems light, probably can get the car back to me later in the day. Of course "later in the day" he says they need to keep it overnight to test it. Call in the morning, 11-12. Morning, 11AM and the SA says "it's still leaking"! (I supplied the exclamation point).

Now being of logical bent I'm trying to figure this out. I imagine it COULD be a bad run of covers and/or oil caps, but other M5s he's seen don't do it (I have no reason to question this, and am glad he gave me the opposite of "they ALL do it"). What else? I ask to see my car (to make sure it's not parked at some McDonalds) and he takes me in to see it, all hooked up with tubes. Not to make light of those with REAL problems, but I feel like I'm visiting a close relative in intensive care (sort of like Walter Matthau at the beginning of a movie I THINK was called "A New Leaf" or "A New" something or other). SA says they're testing to see if there's a vacuum or pressure condition forcing the oil out of the cap.

Well, after thinking about it I suppose that's the only other thing it COULD be. Kudos to them for proceeding logically but my question is (sorry it's been so long since I started this)...anyone heard of anything like this? I searched the forums but most of these stories revolve around a faulty cap or faulty seating thereof.

The only other idea I had was that the oil is 5W-30, very thin when it gets hot, but STILL don't think it should leak out of the cap and, IAC, it hasn't been that hot around here the last few days.

Any pointers to a TSB or discussion would be appreciated. In lieu of flowers donations can be sent to....

=NLK=

mottati · 5th September 2003, 21:41

elevated crankcase pressure can certainly force oil out thru the cap! Certainly not a good thing. Do a search, as I remember someone, i believe in the UK, who had the same problem and ended up with a new short block, due to piston ring wear causing increased pressure in the engine. His symptom was also oil leaking from the cap...

good luck, be happy for warranties....

Mike
00 M5

nlk10010 · 5th September 2003, 21:56

I tried searching and was only able to come up with a thread started by RaveE55 who said this was what the person he sold his car was told. Apparently there was an oil leak which the new owner thought was just a bad cap.

This thing was leaking from the moment I picked it up- I told the salesman and noted it in my journal.

I can't wait to see what happens with THIS.

Thanks for the heads up, Mike.

=NLK=

RM5 · 5th September 2003, 22:31

I have gone thru 3 caps and it still seeps out. I think the caps are not seating right.

F. T. Kirwan · 5th September 2003, 23:12

This used to be a symptom of high pressure in the crankcase. Have they checked for that?

Good luck.

Tom Kirwan

03 Le Mans Blue?Caramel
02 Z3 3.0
04 Cayenne S

Rcl4668 · 5th September 2003, 23:42

Since my car was new I have checked my oil pretty much weekly. Frequently (appr. 50 percent of the time), when I check my oil I notice some oil has seeped out of the filler cap onto the surrounding area. Usually, I also have to add about a quarter to an eighth of a quart of 5w-30 each week to keep it at the full level on the dipstick. For whatever reason, I have always just assumed that this was normal for the engine. Should I have my dealer check this out?

PS: Our M5s don't have an oil pressure guage but oil temperature has always been within normal levels, engine performance has been normal, and I have had the SES light go off only once, due to an improperly tightened gas filler cap.

Thanks for your input,

/Rich

nlk10010 · 5th September 2003, 23:46

RM5: I know, I think I tried 3 caps in total as well (AT LEAST 3). My inclination is to say that the cap's at fault except that other M5s that this dealer has seen do NOT exhibit the problem (I don't know what weight oil they use). IAC, I can't afford to ASSUME it's just the cap. I know you can create problems by trying to fix something that ain't broke but I simply have no way of knowing what's going on.

Tom: You know, I get so flustered when I talk to these guys I forgot to ask, simply, did they test for high pressure. I know they were AWARE of the possibility since the SA mentioned it but I saw the mechanic tonight and he just said he'd done everything BMW had told him to do and now he had to wait for the factory rep to show up on 9/23. I would hope that this had occurred to BMW and that they had asked him to do that kind of test, in which case I would feel relieved since he obviously didn't find anything. But who knows?

Only thing is, he told me he doesn't have time to put the car back together

in time for me to take it today so I'll have to wait until Monday. And I wanted to take it to the Meet at Old Westbury Gardens this weekend.

Oh, well, I'll just listen to the Playboys sing "Over the Weekend" until I go back Monday or Tuesday and go through more angst seeing if they've taken the car home or otherwise damaged it.

Man, I'm not built for this.

Thanks for taking the time to post.

=NLK=

x703jko · 6th September 2003, 01:08

I'm not sure this is relevant to the discussion, but I've always noticed some seepage of oil near the cap. Not enough to make me worry, but enough to make me wonder.

At first my SA told me that it was probably oil that was left around the opening when I topped off the oil. But I am very meticulous when it comes to cleaning the oil fill port. And, whenever I go to top off the oil, I notice that when I open the port, there's always a bit of oil on the part of the port that makes contact with the gasket. When I went back to the dealership the SA told me that was normal and that there would be some seepage due to the high hydrodynamic and aerodynamic pressure that results from the oil circulating through the engine. Not sure I buy that....I would tend to think that the cap should have a gasket that should withstand that kind of pressure.

I'm going to see them next week for an oil change. I think at that point I'm goint to ask for a new cap.

Jeff

mottati · 6th September 2003, 01:16

NLK,
You're right, it was ravee55's post i was thinking about. I had just taken delivery of my 00 M5 when i read it, and upon opening the hood that evening, noticed oil around the cap! I went to the dealer the next day, got a new cap and, touch wood, no oil since.
BUT, there must be some kind of crankcase vent valve (PCV valve, in old world speak) that perhaps could be plugged, allowing the crankcase pressure to increase.
Good Luck,
Mike

MIB · 6th September 2003, 01:28

Very Common problem,

I got the, They all do it, and after awhile it will stop.

Mine could be a little different as I'm not using much Oil, 10W60.

In 9,500 Km's I've used about 2.5 litres. I think this is very minimal considering my car lives at 7,000.

But it looks more like Oil vapour than Oil. It gets shiny around the surround area of the cap like as if oil is leaking out, but when you wipe it with a paper towel, it is dry but there really isn't much on the white towell.

So its almost as if its vapour coming out of the cap. It did stop for awhile but its doing it again. My S/A is not concerned and again said very common.

P.S. My 540 never did it, 3 years never used a drop. He said common for a Beast.