VCG Change, new issues

[TheGreenOx]

(for what its worth, I searched first)

TL: DNR - Changed VCG the (mostly) right way and some problems remain, plus a new hesitation under load around 3k

2000 540/6 m62TU

Finally had a change to do Valve Cover Gaskets today. Used a PDF DIY that's for 740s that many said was good and it seemed to be. Also read a LOT on here. Install went fine and as expected; used glycerine and all that. Covers came right off with no issue and the gasket didn't try and fall out. Used sensor-safe gray stuff on the half-moons and rubbery spot for the upper timing cover as instructed. Didn't take off the metal clips before pulling the electrical boxes off...I trued to pivot the box to see the connectors and they all popped off without issue or protest.

Here's what got weird:

1 - the torque wrench I have was a bit too beefy, lowest setting was higher than the specified values, so I guessed. On the second stud I tightened I went too far and sheared the stud. Its (I think) the second from the front of the 8 that surround the spark plugs. Obviously that's bad, but how bad? Can I back it out (drill) and replace the stud? Or is it something fancy and wholly German? For my guess I went to 'reasonably tight' and added a quarter turn. Worked for the rest of the studs, which I would say (with no empirical certainty) that they're similarly torqued and tight enough.

2 - There was some oil smoke coming from under the engine in front of the pass side, from up under the heads. I'm assuming this was dripped oil during the install, but was still slightly present after a 10 minute run-up and 15 minute test drive. (yeah I did that missing a stud, is that real bad too?). Startup was uneventful aside from some smoke and rough idle that were present prior to this job. (CCV is a little over a year old, had smoke on start issues before, more below)

3 - During that perhaps-not-a-great-idea test drive, it ran pretty well actually! Seemed to notice more power off-idle which was an issue before. However, a few times during the drive I noticed clicking sound (best description I've got, but it could have been a dieseling sound) which was associated with a significant power loss. Usually this was during application of power. If I let off and got back on gas it was normal. But it was enough to curtail the test drive after I tried and duplicated it a few times. Power was as expected during most of the test drive (at least as good as if not better than prior to VCG job)

A few notes that might help:
I was losing light toward the end of the install and its possible the half-moons might night have aligned perfect on the driver's side. I could feel what I was darn sure was the gasket in the right place but couldn't actually see down in there. (I tried) So it may be that simple? I also probably didn't let the RTV (or whatever exactly it is) gasket maker set for long enough. It was probably less than an hour between putting the gasket and cover back on before I started the thing.

A few weeks earlier I discovered that I had a coolant leak (reservoir and a hose) and a bad coolant level sensor because the car overheated. Coolant temp got as high as maybe 260. I have a Scan Gauge II that stays plugged in and gives me (among other things) coolant temp. Reservoir and hose were replaced and its run fine (as good as it did before at least) since. No codes or CEL anywhere. Did get an airbag light as I usually do below 40degF.

I've had some smoke on startup issues in the weeks prior to the overheat and its had an ongoing rough but not terrible idle. Replaced the CCV on the back of the intake manifold about a year ago (meyle) and no issues until a few weeks ago. The amount of smoke was proportional the time it sat, so 10 hours of work = a little smoke (more than a little) but 2 days of sitting waiting for the coolant parts yielded a lot smoke and it cut off after a second or two. Has run fine (as good as before) since then.

I'm out of weekend, light and patience. So I thought I'd throw it up here. I'll retrace my work as soon as I'm able, but I'm pretty darn sure I put everything back or I wouldn't have started the thing. I'll recheck the back 'half moons' and the RTV job as well as double check the injectors. But given that it ran as expected for at least some of that test drive, I'm figuring most of the "hey, dumbass" parts were in place.

If it sits until next weekend (it will) I'll take all that off again anyway as I want to do the intake gaskets, valley pan and all the stupid pipes in there as well. and also an oil change (M1 0w-30 Euro is what I've been using). Haven't done any of the fun bits under the timing covers.

Any thoughts are appreciated, not necessarily looking for the Bible, I'm hoping maybe someone has had similar results before and can share their fix.

[JimLev]

It's still too long, lol.
Didn't read it all. Sounds like you broke the stud that screws into the top of the cam cap. You should be able to back it out after you take the valve cover off. If you can't get it out Harbor Freight sells left hand drill bits.
I never use a torque wrench on the valve cover. A 1/4" drive ratchet is fine, just keep tightening all of them in a crisscross pattern until they are bottomed out, then just a slight tweek more and your done.

[geargrinder]

re: the smoke/oil - yeah its really hard to tell in a case like this - do your best to wash down the oil and be sure anything is 'new' before jumping to conclusions...