The Tappet Cover's Function on a e39

[B5vZ]

Hi guys,
I would love for someone with a bit more technical knowledge to explain this one to me: I have a 2001 e39 525, and I went to the mechanic today to find out what the burning smell is in my car after long drives.
After inspecting it he concluded that it was oil leaking from the engine, and when it heated it caused the burning smell (fair enough; I understand that much).

Now here is what I don't get:
he told me that it might be from a cracked tappet cover (the black plastic part over the engine with the BMW logo etc.), and this is where I got confused: I always though the tappet cover was a purely aesthetic part of the engine, to hide the mechanics under it from us mere mortals, and that any oil leakage problems would be from underneath the tappet cover (e.g. tappet seals etc.), and so fixing a cracked tappet cover would not be solving anything, but merely cover any problem underneath it, since the engine shouldn't be leaking oil ever anyways, even with the tappet cover completely off, and so the problem lies somewhere under the cover.

Is what I am saying in anyways true, or am I just being an absolute n00b?

 

[zaleonardz]

Not quite dude

Your getting confused between an engine cover and the tappet cover, also known as a rocker cover.

Its the cover that directly fits over the head to close it off, its a common failure point on many BMW's, or at least the seal, so if your picking up weird burning smells, your mach is probably correct.

Not saying that he is, but it is plausable.

Case in point, if you removed all the engine covers, the tappet cover would stay behind as you need to remove about 12 screws from it..

Hope this helps.
:rollsmile:

 

[whattingh]

engine cover with logo on
tappen cover
seal. Normally the one that cause the leak

 

[Sankekur]

If the gasket is leaking especially on the parts that go around the sparkplug holes be sure to replace is at soon as possible, as oil leaking into the sparkplug holes could lead to damage of the coil packs and you don't want to have to replace that as well.

 

[B5vZ]

Thanks for all the help.
I'm having the car serviced on saturday, and hopefully the leak is small and has nothing to do with the tappet cover (here's hoping).

 

[P1000]

Oh, and the cover you were first talking about, is called an acoustic cover. I think from the name that it has as much to do with blocking sounds as it does making it look prettier.

 

[zaleonardz]

tappet cover and or gasket replacement is a 15 minute job, maybe 20 minutes....

 

[P1000]

Whoops, accidentally clicked on the thanks button, meant to reply, but no worries, Leonard definitely deserves a thanks, and I see no one has given him any yet.

Leonard, you forgot to add the 45mins it takes to remove all the acoustic covers before you get to the tappet cover.

 

[msm]

Agree with ZL.

I common fault on this engine is not the engine cover gasket, but the valve cover gasket (or also known as tappet cover gasket) that develops leaks. Oil then drips onto the cats/headers causing the burning smell.

90% chance of that causing the problem and not the engine cover gasket. It's difficult to trace because the headers are so hot, it dries out that whole area when hot (and also produces the burning smell).

---

tappet cover and or gasket replacement is a 15 minute job, maybe 20 minutes....

Took me about 1 hour to do it, cos I cleaned every little bit before I put it back.

---

One more thing for this job: Inspect the little rubber gromets that go around the bolts - some of them are the cause of the leaks too. It may be worthwhile replacing all the lower ones (about 4) as they tend to become stiff with age.

 

[B5vZ]

Took the car in on Saturday and it turns out it is a cracked Tappet Cover, but the crack is on the outside, so no damage to the actual engine. Couldn't get it replaced Saturday, since they didn't have stock or time to order me one, so getting it replaced some time later this month.

Guess I just have to drive a bit slower then usual.

Thanks again for all the help guys

 

[whattingh]

hmmm what could have caused a tappet cover to crack.....?

All I can think someone dropped something heavy on it.....

 

[msm]

hmmm what could have caused a tappet cover to crack.....?

Was also pondering this???

 

[B5vZ]

Heat/Expansion/Contraction over 10 years, would also do the trick.

Whatever the reason is, I trust that my mechanic isn't trying to conn me or anything