E90 330xi Exhaust Bolts

[turbojimmy]

Hi all -

I'm replacing the flex disc and center bearing on our '06 330xi. Step one, and the step I dreaded the most, is removing the exhaust system.

The job is going as poorly as I had predicted. I was able to remove 2 nuts where the pipes meet the manifold and snapped off a third. The 4th and last is in a tough spot - the pipe configuration won't let me get any sort of saw or cut-off tool in there. Any tips or tricks to getting at that exhaust bolt? I have some tools for extracting rounded nuts that I haven't tried yet, but I don't think I can get them up in there either.

With regard to the bolts/studs - are they replaceable? They don't seem to have a head on them. Are they pressed into the manifold? Can they be tapped out and replaced with bolts? Or do I have to drill them out?

Thanks!

[White94RX]

They are pressed in. Your best bet is to go ahead and break it off. Once that's done, you can remove the exhaust, and then comes the hard part. We use a torch to heat them, and then a hammer to knock them out. Just use some nuts and bolts when you go back together. Or go to the dealer and buy the studs if you wish, but there's no point really. I can't remember how close the o2 sensors are in that section of the exhaust, but if they're close you better remove them before getting the torch out. The heat will kill them.

[turbojimmy]

They are pressed in. Your best bet is to go ahead and break it off. Once that's done, you can remove the exhaust, and then comes the hard part. We use a torch to heat them, and then a hammer to knock them out. Just use some nuts and bolts when you go back together. Or go to the dealer and buy the studs if you wish, but there's no point really. I can't remember how close the o2 sensors are in that section of the exhaust, but if they're close you better remove them before getting the torch out. The heat will kill them.

Thanks. I figured as much. I'll just work that last stud until it snaps. I'll also have to look again where the O2 sensors are. Not sure where my acetylene torch is at the moment so I'm going to try a MAPP gas torch first and then try to bang them out. If that doesn't work I may just drill them. They seem to be pretty soft. I'll just put regular nuts and bolts back in.

[White94RX]

Get a torch. MAPP gas should work fine. You'll never be able to drill them out. And how would that work anyway? Just drill a hole down the center and break it into pieces? Remember, these studs are pressed in, not threaded. They don't unscrew.

[turbojimmy]

Get a torch. MAPP gas should work fine. You'll never be able to drill them out. And how would that work anyway? Just drill a hole down the center and break it into pieces? Remember, these studs are pressed in, not threaded. They don't unscrew.

Yes - drill a hole down the center and they break into pieces. The cast iron manifold is harder than the soft steel bolts. The drill finds its way. Or at least it has on everything else I ever worked on. This BMW has always proven to have its share of surprises.

I'll try the MAPP first. If not I'll find my acetylene torch. I haven't seen it in a while - probably lent it to someone.

[turbojimmy]

Well after a lot of research I decided not to drill. I heated it up with an oxy/acetylene torch but the stud wouldn't come out.

And I should have listed to your advice - it evidently cooked the O2 sensor. I have a P0036 code now.

Good news is that it feels great with the 2 new flex discs and center bearing. I'm taking it to a local shop to remove the broken stud, then I'll replace the O2 sensor. Mo' money....

[White94RX]

You couldn't get it out with a torch? I've never had an issue with the "hot wrench". Heat it up till glowing, and smack it a couple times with a 3 lb sledge, and the pop out every time.

[turbojimmy]

You couldn't get it out with a torch? I've never had an issue with the "hot wrench". Heat it up till glowing, and smack it a couple times with a 3 lb sledge, and the pop out every time.

That's what I did, but using a MAPP gas torch which may not have been hot enough. The bolt was glowing but not the manifold flange. I have an oxy-acetylene torch but to be honest I don't have a lot of experience with it. I didn't want to use it in such a confined space (car is on jackstands, not a lift) and near other stuff that I could potentially set on fire. It will cost me a little more to have the local muffler shop do it, but I'm going to have him pop in the new O2 sensor which will save me the hassle of having to get back under the thing.

[White94RX]

Sounds like a good option at this point. I guess not everyone has access to a lift like I do.

[turbojimmy]

Sounds like a good option at this point. I guess not everyone has access to a lift like I do.

Yeah a lift is on my wish list. I had one at my prior residence but had no where to store it while I was between homes so I sold it with the house. I regret that because now I have optimal ceiling height in my new house (the old one was tight). The budget is now the limiting factor