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E39 (1997 - 2003)
The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki

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Old 03-26-2014, 09:19 AM
monkeyman_69 monkeyman_69 is offline
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exhaust manifold studs

I'm chasing a small oil leak(s) at the exhaust manifold. I replaced the VCG and it's solid. Mirror/flashlight and fingers all show it's dry. I think I'm getting oil leaking out around the threads on the studs holding the manifold to the cyl head. I unbolted the manifolds and in the process about half the studs came out, too. 2 of them came out w/ metal shavings. An E46 forum says sometimes the stud seizes to the aluminum. A BMW mechanic friend said not to worry, just thread in the new one. So... 1) should I remove all of them and add non-locking loctite to new studs to stop the oil leaks? 2) Should I leave the studs that didn't come out and live w/ the slow leak? 3) Since 2 holes may be stripped, do I have to tap or helicoil them? '97 528i, 260K.
PS. I've scoured this forum and can't find this exact problem. And thanks to all; you've helped me fix my tie rods, radiator, sunroof, hood release, radio, and trunk latch.
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Old 03-26-2014, 09:27 AM
JimLev JimLev is offline
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I don't have an I6 or ever taken the exhaust manifold off one but I doubt that the exhaust studs holes would be the source of leaking oil.
Are you sure the oil is coming out of the stud holes or did it run down from the valve cover gasket when it was leaking?
As hot as the studs get the oil should be burned off.
A remote possibility is the head is cracked somewhere.
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Old 03-26-2014, 10:28 AM
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bartelbe bartelbe is offline
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Quote:
Originally Posted by JimLev View Post
I don't have an I6 or ever taken the exhaust manifold off one but I doubt that the exhaust studs holes would be the source of leaking oil.
Are you sure the oil is coming out of the stud holes or did it run down from the valve cover gasket when it was leaking?
As hot as the studs get the oil should be burned off.
A remote possibility is the head is cracked somewhere.
You are correct, the i6's exhaust manifold bolts holes are not open to inside the head. Start looking else where for your leak.
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Old 03-26-2014, 10:32 AM
monkeyman_69 monkeyman_69 is offline
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2-3 studs seem "wet". I don't drive the car much. It sits and when i start it, a little white smoke along the exhaust manifold. It's gone in a minute. The car sits again (days to weeks), then smokes again. If it's leftover oil from a bad VCG, why would the studs re-wet w/ oil? I can see it on the end before starting. I can't rule out a crack though. I've heard of some engines where stud holes go thru into oil channels. Not sure if the I6 is like that.
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Old 03-26-2014, 10:36 AM
monkeyman_69 monkeyman_69 is offline
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I missed bartlebe's comment. Thanks.
If there is no flowing oil on the back side, I'm left w/ these options: a crack or old oil from the VCG, right? I'll just live w/ a crack until she dies. What about my existing studs and shavings from 2 holes?
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Old 03-26-2014, 10:46 AM
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bartelbe bartelbe is offline
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Tiny shaving is normal, aluminum threads on the other hand not so. The bolt holes are fairly deep and as rule of thumb 7 good engaged threads is all that is needed to take advantage of the bolts/studs strength. I used silver anti-seize thhe studs.
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Old 03-26-2014, 11:00 AM
JimLev JimLev is offline
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Wipe off the area just below the valve cover next time the engine has cooled down and then do it again before you drive it.
If it's wet the valve cover gasket is leaking.
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Old 03-26-2014, 02:04 PM
monkeyman_69 monkeyman_69 is offline
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The car hasn't run in over a week. I'll do the wipe test and report back.
As for 7 threads, I should have enough. Not that many shavings came out. Do I use the double nut technique to get the current studs out and to install the new ones? Or should the new ones go in by hand? Don't want to over torque them.
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