I think my oil filler cap is leaking...

adg44 · Post by **adg44** » Tue Oct 16, 2007 6:44 pm

Here is the story:

I topped off about .3 quarts yesterday, and I cleaned the cap and everything around it - it was spotless.

I was riding today and I looked down and noticed that oil had trickled down the front of the valve cover, and the cap was oily.

I assume the cap just needs a new o-ring or something simliar.

Has this happened to anyone else? I only have 8,200 miles.

- Anthony

Ves · Post by **Ves** » Tue Oct 16, 2007 7:08 pm

Yeah, do a search, there's threads on this. I bought all the parts, replaced them, and it hasn't leaked since. You need the piece the goes into the valve cover, the o-ring that goes with it, a new cap, and new cap o-ring. I think all the parts together are less than $10.00.

Post by **wncbmw** » Tue Oct 16, 2007 7:52 pm

Before you go too far, be sure that all the surfaces are clean when you put it back on. I had some weeping at the oil cap and members of this board advised me to clean with a rag before screwing it back in. I did and the weeping stopped, never to return.

If that doesn't work, then replacement parts might be in order.

adg44 · Post by **adg44** » Tue Oct 16, 2007 7:55 pm

wncbmw wrote:Before you go too far, be sure that all the surfaces are clean when you put it back on. I had some weeping at the oil cap and members of this board advised me to clean with a rag before screwing it back in. I did and the weeping stopped, never to return.

If that doesn't work, then replacement parts might be in order.

I had cleaned the cap and the filler "neck" after I topped off.

Here are the parts that I found:

11 14 7 659 578 filler pipe 1 $4.50
11 14 1 340 901 o-ring 1 $1.50
11 14 1 340 900 oil cover lid 1 $3.10
11 14 1 340 902 o-ring (18X4) 1 $2.00

paithorn · Post by **paithorn** » Tue Oct 16, 2007 8:34 pm

Yup, mine was similar case recently and it is solved with the o ring replacement.......

Sunbeemer · Post by **Sunbeemer** » Tue Oct 16, 2007 8:47 pm

Same here. Replaced o-ring in cap and slowed it down to almost nothing for several months, then leaking returned and I replaced o-ring around filler pipe and no leaks since (over 1 year ago). Note: the Filler pipe came out easily with the valve cover off (during a valve adjustment) but I couldn't remove it with my finger through the hole with the cover on, it had to be pushed out from inside the valve cover. There have been some threads about this in the past.

riceburner · Post by **riceburner** » Wed Oct 17, 2007 6:27 am

Check you remove the o-ring and dry it off AS WELL as cleaning the cap and the neck.

Post by **rdsmith3** » Wed Oct 17, 2007 8:26 am

I have replaced the whole assembly twice, and it stops the leaking each time. However, eventually things loosen up and the leaking returns. I guess I will have to make this an annual maintenance task.

Capt. Blackadder · Post by **Capt. Blackadder** » Wed Oct 17, 2007 9:47 am

rdsmith3 wrote:I have replaced the whole assembly twice, and it stops the leaking each time. However, eventually things loosen up and the leaking returns. I guess I will have to make this an annual maintenance task.

Or, you could get Viton replacement O-rings from somewhere like McMaster-Carr. That ought to stop the leak for good.

geothepencil · Post by **geothepencil** » Wed Oct 17, 2007 10:04 am

Oiled up my shoe quite nicely one day. A new O ring fixed the leak. It still mists a little around the cap. Guess I'll do the whole thing someday.

geo

wile e · Post by **wile e** » Wed Oct 17, 2007 5:47 pm

Will the locking oil cap fix this problem or does it tend to have the same problems after awhile as well?

Post by **challey** » Wed Oct 17, 2007 6:08 pm

Will the locking oil cap fix this problem

Not sure about the locking oil cap but the Moto Techniques http://www.moto-techniques.com/bmw.htm cap definately cures the problem permanently. And even though it doesn't lock, since it requires a hex key to remove, it offers a fair degree of protection from your average neer-do-well. The only draw back is the price (~$60 with shipping) but it's a one-time purchase.

Charlie

wile e · Post by **wile e** » Wed Oct 17, 2007 6:31 pm

Cool thanks Challey.

Post by **rdsmith3** » Thu Oct 18, 2007 10:35 am

Capt. Blackadder wrote:
rdsmith3 wrote:I have replaced the whole assembly twice, and it stops the leaking each time. However, eventually things loosen up and the leaking returns. I guess I will have to make this an annual maintenance task.
Or, you could get Viton replacement O-rings from somewhere like McMaster-Carr. That ought to stop the leak for good.

Do you know that for a fact? We are dealing with cheap plastic parts that do not fit well, and that continually expand and contract from heating/cooling (and probably expand/contract in a different way than the metal). It is not a great design. Is it true that a different type of O ring will overcome the problems and create a better seal?

One of those fancy metal caps might be the cure, but I am reluctant to spend $60 for an oil cap.

Post by **challey** » Thu Oct 18, 2007 10:52 am

I very much doubt that replacing what is probably a Buna-N O-ring with Viton will be a permanent fix for the problem. As rdsmith notes, the root of the problem is the design and materials of the plug assembly. Not only does the plastic oil plug not expand at the same rate as the Mg valve cover, it also becomes more flexible when hot which has to affect its power to effectively seal things.

The metal replacements are pricey but it's a one-time expense. For 60 bucks, you not only fix the problem for good, you also get the peace of mind that comes with knowing that you will not get stuck on the road due to an oil plug failure and that a malevolent passer-by can't easily remove the plug. BTW, the MotoTechniques plug comes with Viton O-rings in place.

Seemed like good value for money to me, which is why I changed things out before I had a problem.

Charlie

Post by **sjbmw** » Thu Oct 18, 2007 11:44 am

+1 challey.

I picked up the BMW locking cap for $35 at my dealer's open house a few years ago.

Be on the lookout for dealer open house discounts for this type of stuff, can save a few sheckels....

Capt. Blackadder · Post by **Capt. Blackadder** » Thu Oct 18, 2007 12:11 pm

No, I don't know that for a solid fact, hence the "ought to" part of my reply. However, the Viton O-ring solution has worked perfectly for my cam chain tunnel covers for almost five years now, and I have no reason to think that the same won't apply for the oil fill cap.

Post by **ProductUser** » Thu Oct 18, 2007 12:23 pm

rdsmith3 wrote:I have replaced the whole assembly twice, and it stops the leaking each time. However, eventually things loosen up and the leaking returns. I guess I will have to make this an annual maintenance task.

I am very careful not to spill any oil around the plastic assembly. If I do, I pop it off, clean it, reinstall.

Once I'm done adding oil, I will clean the fill cap, fill cap o-ring, the assembly the receives the fill cap o-ring with a rag saturated with soapy water. This removes all of the oily residue. I've been using the same o-ring and assembly for over 30k miles.

ProductUser