habbyguy

Yes, re-using aluminum bolts will result in that kind of carnage. OTOH, the aluminum bolts that are NOT TTY (Torque To Yield) are fine to re-use (like the many bolts that hold on the transmission pan/filter, for example).

I just finished (among other things) replacing my valve cover gasket. Had something go south in the valve train (bumped one of the rollers that transfers the Valvetronic cam's input to the intake lifters, when putting the valve cover back into place), so got to take the valve cover off again, and replace the gasket, and of course, all the bolts. Sigh...

Ryengoth

My N54 VC does not have tty alum screws. They are held in the cover with retention collars so they don't fall out. Also there are 3 grounding studs that hold half of the inner cover down. Those aren't replaced.

I know the pan screws were TTY replaceable due to sealing force. The windage tray, though? That's absurd. I put less than 4lbft on those 4 and they didn't even snap. They FELL in half. That means that they were already stretched beyond tensile strength when installed. Wonder why the oil pans leak? Those damn TTY alum screws stretch overtime and let the seal loose. I've a mind to replace them all with 316 screws to eliminate that.

habbyguy

It can be tricky getting the right (very, very low...) torque on those small TTY aluminum bolts. I botched a couple myownself doing my valve cover, getting used to the new 1/4" torque wrench (the click was very subdued). Could be someone over-torqued them originally, and they stretched to the point of almost-but-not-quite-failure.

I know that sometimes the aluminum bolts are there because steel bolts will react badly with the material they're threaded into, but I think I'd have preferred having to use anti-seize with steel bolts!

Ryengoth

No, those screws are absolute crap. Might as well use nylon. They are not cut from 6061 which would never shear like that from stretch. I have many parts CNC cut in it and it's not that. Most automakers that choose to use cast alum for the engine block choose either aluminized steel fasteners or zinc galv. It comes down to casting quality, alloy quality, fastener torque, thread depth and blind versus open hole with sealant. Galvanic seize can be caused by dissimilar metals but if thread sealant or threadlocker is used there's less room for it to build up and cause thread seize. Either way, the BMW service manual has instructions on EVERY bolt removal to use heli-coil thread repair as needed. They EXPECT their engine block fastening engineering to fail. As so many say, if you can't afford a BMW new you can't afford a used one either.

banglenot

I'm rusty on the N54, but on my N52 the aluminum TTY's were because of the block assemblies alloys reaction with steel.

I dropped the oil pan (meaning I dropped the front frame assy 6 inches to get enough room to pass through the pan) because of an oil seep at 90K miles.

I saw you dropped yours. For me, it was a great time to drop in engine mounts because the engine was supported as I dropped the frame. The mounts were cheap.

Also, monumental suckage to work on jackstands. There's a youtube out there where a guy built support boxes out of 2x4, raised the car about 18"-24" for a big improvement in comfort. 10 layers = 18". My guess is he could easily add another 6" for real comfort under there. Also, the lumber is probably worth more than the car.

Ryengoth

Already swapped the mounts. Also doing a trans pan and fluid change as well as xfer case fluid change and new o-rings on the diff stub and mid-bearing bracket.
So the block apparently is magnesium. That worked out so well for Pontiac Fieros that most of them are gone from flaming blocks.

Ryengoth

When you have to remove the entire front suspension to fix an oil pan leak you can't set the front wheels on anything...

Ryengoth

Two of the 4 broken windage tray screws came out without a problem using left-hand bits. The other two required drilling and repair so I used a couple M6 Time-Serts from my master kit with the tails ground off so the screw will pass through it. Installed with orange Loctite so they can be removed if needed later. The book says to use helical coil repairs but I've never used them. If these have to come out at some point it won't be me dealing with it and I doubt the car will live that long anyway.

twh

N52 has magnesium block superstructure.
N54 is all aluminum.
I've used Time-Sert before, they are very nice.