Oil fill cap leaking

[chamba002]

Also, wipe off the excess gasket sealant too... I did that after I initially placed the oil cap back onto the valve cover. After wiping the excess sealant I placed the cap back on and let it cure for a day. Cheap and simple fix.

[wahwill]

I had this issue and took the gasket out to take a close look. The gasket had a slight crack in it which I'm sure caused the leaking.

I flipped the gasket around, cleaned it thoroughly and put it back on. It stopped leaking after that but got a new cap and gasket under warranty anyway.

[victrams]

I had a leak at the filler cap and tried different caps but it still leaked. Dealer recommended I replace the whole valve cover. I noticed once the paints start to wear, there is an uneven lip surface by the filler hole. I lightly sanded the lip to make it smooth and put some high temp touch up paint to seal it. Just make sure you confirm that it is from the filler cap area by cleaning first and seeing where the oil starts from. Leak has been gone and hoping it stays that way.

[Z K]

Originally Posted by victrams

I had a leak at the filler cap and tried different caps but it still leaked. Dealer recommended I replace the whole valve cover. I noticed once the paints start to wear, there is an uneven lip surface by the filler hole. I lightly sanded the lip to make it smooth and put some high temp touch up paint to seal it. Just make sure you confirm that it is from the filler cap area by cleaning first and seeing where the oil starts from. Leak has been gone and hoping it stays that way.

I have the same problem. I tried all sorts of different oil caps, including the ones mentioned in this thread. None were working for me. The surface of the lip that the cap mounts to is chipped and the surface is uneven.

How did you sand down the surface without dropping stuff into the oil? For touch up paint, aren't those usually sprays? Did you get a brush on one?

[IamFODI]

Originally Posted by Z K

I have the same problem. I tried all sorts of different oil caps, including the ones mentioned in this thread. None were working for me. The surface of the lip that the cap mounts to is chipped and the surface is uneven.

How did you sand down the surface without dropping stuff into the oil? For touch up paint, aren't those usually sprays? Did you get a brush on one?

I finally got around to doing this sanding operation based largely on doogee's advice.

First, I dampened a piece of a shop towel with oil so that dust would have an easier time sticking to it, and put it in the fill hole. Then I got my sweet Metro Vac hand vac, put the flex hose and crevice tool on it, turned it on, held the nozzle on the inner edge of the hole next to where I was sanding, and took it nice and slow. I tried to move the sandpaper and vac nozzle in unison. I figured that between what debris fell outside the engine, what the sandpaper held onto, what the vac picked up, and what fell and stuck onto the shop towel, little if anything would enter the engine.

Afterward, I cleaned up first by running the vac nozzle around the rim, and then by wiping the rim down inside-to-outside before gently extracting the shop towel. Then I poured a little oil onto the cam gear and chain to rinse them off for good measure.

It looks like I still have a leak, but it's MUCH slower now -- like a weep, almost unnoticeable.

FWIW.

[doogee]

Originally Posted by IamFODI

I finally got around to doing this sanding operation based largely on doogee's advice.

First, I dampened a piece of a shop towel with oil so that dust would have an easier time sticking to it, and put it in the fill hole. Then I got my sweet Metro Vac hand vac, put the flex hose and crevice tool on it, turned it on, held the nozzle on the inner edge of the hole next to where I was sanding, and took it nice and slow. I tried to move the sandpaper and vac nozzle in unison. I figured that between what debris fell outside the engine, what the sandpaper held onto, what the vac picked up, and what fell and stuck onto the shop towel, little if anything would enter the engine.

Afterward, I cleaned up first by running the vac nozzle around the rim, and then by wiping the rim down inside-to-outside before gently extracting the shop towel. Then I poured a little oil onto the cam gear and chain to rinse them off for good measure.

It looks like I still have a leak, but it's MUCH slower now -- like a weep, almost unnoticeable.

FWIW.

Nice you got around to it!

If you didn't give the gap a thorough cleaning, the oil you're seeing could just be a little residual from underneath the seal on the cap.

[IamFODI]

Originally Posted by doogee

Nice you got around to it!

If you didn't give the gap a thorough cleaning, the oil you're seeing could just be a little residual from underneath the seal on the cap.

Had the same thought. Gonna monitor it.

[Redd]

I had the same oil cap leak when I got my car. Changed the oil cap for the one from the E46 M3 which some forums said was tighter. Leaked reduced significantly but still slowly wept oil over time.

Then I replaced my valve covers due to the paint bubbling. Zero leaks since then, using the same E46 M3 oil cap.

[dparm]

As I've mentioned before, a little bit of weeping is normal. Oils that contain esters have some polar action so it will actually climb up the threads and down the side -- you often see this on opened bottles of oil that have been sitting around for a while.

[///M Power-Belgium]

Originally Posted by Z K

I have the same problem. I tried all sorts of different oil caps, including the ones mentioned in this thread. None were working for me. The surface of the lip that the cap mounts to is chipped and the surface is uneven.

How did you sand down the surface without dropping stuff into the oil? For touch up paint, aren't those usually sprays? Did you get a brush on one?

Originally Posted by IamFODI

I finally got around to doing this sanding operation based largely on doogee's advice.

First, I dampened a piece of a shop towel with oil so that dust would have an easier time sticking to it, and put it in the fill hole. Then I got my sweet Metro Vac hand vac, put the flex hose and crevice tool on it, turned it on, held the nozzle on the inner edge of the hole next to where I was sanding, and took it nice and slow. I tried to move the sandpaper and vac nozzle in unison. I figured that between what debris fell outside the engine, what the sandpaper held onto, what the vac picked up, and what fell and stuck onto the shop towel, little if anything would enter the engine.

Afterward, I cleaned up first by running the vac nozzle around the rim, and then by wiping the rim down inside-to-outside before gently extracting the shop towel. Then I poured a little oil onto the cam gear and chain to rinse them off for good measure.

It looks like I still have a leak, but it's MUCH slower now -- like a weep, almost unnoticeable.

FWIW.

=> https://www.m3post.com/forums/showthread.php?t=704497

[SAMM3Y]

Originally Posted by dparm

As I've mentioned before, a little bit of weeping is normal. Oils that contain esters have some polar action so it will actually climb up the threads and down the side -- you often see this on opened bottles of oil that have been sitting around for a while.

I have the new style oil cap on newly refinished vc's... it still has a thin oily film around the neck, this makes sense appreciate the info... thanks

[IamFODI]

Originally Posted by dparm

As I've mentioned before, a little bit of weeping is normal. Oils that contain esters have some polar action so it will actually climb up the threads and down the side -- you often see this on opened bottles of oil that have been sitting around for a while.

I've noticed oil weeping down the side of an opened bottle of oil, but I figured that was from residual oil on the threads. I don't think I've ever seen it after thoroughly cleaning the threads on the bottle and cap.

Either way, this explanation does make some sense. Wouldn't it also suggest that there should be a difference in leakage rates for different oils?

[Shredicus]

I've actually ruined some clothes by storing an opened (but TIGHTLY sealed) bottle of ester-based engine cleaner near them. As mentioned by dparm it literally crept up and out of the bottle... Really odd behavior.

[rpedroza83]

I have bought two oil caps at BMW dealer and still have the leak too. I have 70k miles and now my valve cover are leaking as well too. Are ya'll seeing this issue too?

[M3MPH1S]

Originally Posted by rpedroza83

I have bought two oil caps at BMW dealer and still have the leak too. I have 70k miles and now my valve cover are leaking as well too. Are ya'll seeing this issue too?

My mileage was higher than that, but as described in the OP, my valve covers went around the same time as the oil cap issue cropped up. I posted an update on the OP and someone else in the thread had the same solution - I would 100% recommend using some type of gasket maker to fix the oil cap issue and I would definitely recommend replacing your valve cover gaskets AND spark plug tubes.