Oil on exhaust heat shield: valve cover NOT leaking.

[betsy325e]

Dear Thirtiods,

http://www.realoem.com/bmw/enUS/show...diagId=11_1047

I've got oil on top of my exhaust heat shield after driving around. Not a lot, basically just a thin film of it that smokes just enough to be annoying.

Naturally, I assumed the oil was coming from my valve cover gasket -- replaced gasket. Oil still there.

Then I checked the valve cover for flatness with a straight edge and feeler gauges. It was a little wowed, but nothing crazy.

I just now cleaned everything, had a very thorough look for a crack or SOMETHING..., applied RTV to the areas where I suspected it must still be leaking oil from on the valve cover gasket (basically to the left of spark plug #1 and to the right of spark plug #3). Drove it around. STILL OIL. Definitely not coming from above.

I thought MAYBE a tiny leak was spraying coolant on the heat shield...but no. Just a tiny film...no spray anywhere...no spray on anything in the way. I don't get it.

I remember reading somewhere that oil can "wick" out the exhaust studs...is that true? I can see that there is definitely oil on the manifold right below where it's showing up on the heat shield. ...Anyone ever come across this? Driving me nuts.

[jlevie]

The only places that oil could be coming from are the valve cover, oil filer cap, or camshaft sprocket seal. Throughly clean that side of the engine and watch for the first sign of seepage.

The holes for the exhaust manifold studs are blind, so there is no way for oil to work out there.

[dnguyen1963]

The oil level sensor can be leaking too and the radiator fan can blow it up there, might be a stretch here.

[betsy325e]

Yeah, I didn't think the oil "wicking" on the studs made much sense...why they'd need to go through the block seemed a little ridiculous haha. But I thought I'd entertain it just because I have no idea wtf this oil is coming from. I did see on the same thread that it could be the cam sprocket seal...I'll have to give that a much more thorough once over tomorrow, but how it's selectively and consistently making it down to cylinder #1, past cylinder #2 and on to #3 on the heatshield...no idea if it is that.

I'm really quite stumped. Like I said,everything above where the oil is collecting on the heat shield is nice and clean. Only shows up on top of the heat shield for cylinders 1-3, and only underneath cylinders 1 and 3...the area where 2 sits is perfectly clean.

Only shows up once the engine is at operating temperature...but I can then sit there and stare for minutes (and, oh -- believe the time I have spent staring at this trying to figure out wtf ...) while the engine runs and not see anything to indicate wtf the leak is coming from.

[jlevie]

If you can't easily spot the source, adding dye to the oil and observing with a UV light almost always works. Most any shop will have the dye and light and the cost should not be much for the test.

[TobyB]

You were thinking of the M10. The exhaust studs go through on those.

t

[betsy325e]

UV dye. That sounds like too much fun NOT to play with. Thanks, gonna check that out.

I definitely wasn't thinking of the M10. I barely know anything about the M20, let alone the M10 haha. Thanks for giving me the benefit of the doubt.

[jlevie]

You will be amazed at how well (and fast) the dye and UV light works.

[betsy325e]

Do I need to do an oil change after putting magical from the future dye in the oil, or is it (as I would assume) not an issue for it to be in there for the next 2,500 mi?

[jlevie]

I normally change the oil and filter after using the dye. That may not be necessary, but I've never found an authoritative reference that says anything about that issue. I figure that the oil and filter is cheap and there is no point, in my mind, of taking chance.

Assumptions, unless based in sound data, are a really bad idea and can be dangerous.

[jeffnhiscars]

I've used the dye ($6@ oreilly) and left it in there. You only use an ounce or 2 so there's not much dilution in 5 qts of oil. It also gives the oil a very cool green shimmer that adds a whole new dimension to checking the dipstick :)

[dnguyen1963]

For those who want to know...

https://en.wikipedia.org/wiki/Fluorescein

[Old city bimmer]

That's pretty cool on the dye test.