The top of my valve cover on my 617 engine is noticeably oily. Typically, what is the source of this film? Is it the breather hose on top or the gasket on the cap? Also, my breather hose has a strange hose clamp I've never seen before. Fits perfectly, so it looks factory, but there's no tightening screw. Is this normal?

Thanks for any advice out there.

Doug

There is no such thing as a normal oil leak. It can be the breather hose or the oil cap.

The breather hose often gets a split down the seam that can be difficult to see. Take it off and inspect it. If it is cracked you can replace it with the new style flat hose upgrade or the same style you already have.
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The oil cap leaks past the rubber seal. You can replace the seal or the cap but it can still leak. If you apply some high temperature wheel bearing grease to the seal it will stop the leak completely.

Hey! That's a good idea!

I try to keep my engine pretty clean, but I always have a little seepege arount the breather tube and oil cap. Hopefully, this will fix it.

One thing on the breather hose clamp: It needs to be oriented correctly. If you look closely, there are indentations on the hose that correspond to the shape of the clamp. You'll get a much better seal if the clamp is situated correctly.

Thanks for the replies. When I said "normal," I was referring to the hose clamp. Mine doesn't have a screw on it. Is that the way it's supposed to look or am I missing the screw?

I seem to recall that the clip for the breather is a spring type clip. Does it have some "nubs" on it to grab and compress with pliers?

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

No screw on my clamp either. It's the same as yours.

Pull the clamp off and look at the hose closely and you'll see what I'm talking about.

Right its a spring style clamp meaning its most likely original. The indentations are just from the clamp's pressure compressing the plastic over the decades.

Speaking of time, its likely lost much of its clamping force over the decades. I'd go ahead and replace the clamp with a worm-style clamp and see if that stops the leak. Just don't overtorque the clamp.

if this comes off how fast can it drain the oil down to a dangerous level? Lets say it splits and completely pops off. Just curious, im doing a LONG trip soon. Of course, I will be inspecting the car at every rest stop/gas station

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1981 300SD 512k OM603

At worst it will make an oil stain on the hood pad. You can't run the engine dry with a broken breather hose.