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Discussion Starter · #1 · (Edited)
My first post should save many e36 owners a lot of trouble and time. My E36 appeared to have smoke leaking from the rear of the valve cover near the firewall. I changed the valve cover seal, spark plugs, pcv valve kit and the boot. None of the work I did fixed the problem of the smoke blowing into the air vents and stinking me out of my first used black BMW. After I did all the work and the smoke still appeared in the same location. WTH!!! Problem solved thanks to me going about everything the hard way for you in advance.

Some other people call this smoke blow-by or blowby.

Start your engine from cold wait till your smoke appears like it's pouring out of the valve cover. Then take off the oil fill cap and it appears like the leak moved from the valve cover seal to big hole you just made in the valve cover by removing the cap and releasing the pressure. Right? LOL! NO! Read on and try this test.

Now cover and seal the oil filler cap seat hole for the oil fill cap with your hand. Test the temp first to make sure you don't burn yourself.

Where did all that nasty smoke smell go? What the fish? The smoke disappeared into thin air?


Sorry I'm laughing at myself for doing a lot of extra work.

The aluminum valve cover seat ring is pitted so the rubber gasket on the oil fill cap can't work properly. The cheapest fix sounds a little crazy but works great! Coat inside the filler cap lip, both sides of washer and the cap valve seat with valve cover sealant. Put the cap on with sealant wet still. Then wipe a ring of sealant around the gap between the valve cover seat and the oil filler cap. Wait for the full cure time for the sealant and your done.

Use your dipstick tube to fill the engine with oil for now on when you do oil changes. Just buy a funnel that has a small output filler hole.

TIP: Clean all surfaces completely before applying the sealant.

Some people think there is an oil leak and that may be but if my test works you don't have an oil leak you have a leaking valve cover oil filler cap seat or a bad seal washer inside your filler cap.

Please reply with comments:)

D'oh, You Kids!
1984 633CSi, 1985 635CSi, 1985 325e, 1987 325is, 1993 325is, 1995 318is, 1995 M3, 2003 F150
31,082 Posts
You could just by a new oil filler cap for $15. :dunno:
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