[Yozh]

Finally, had my spare EGR machined and plugs pressed in. Swapped that over. And on the weekend decided it's about time to loose my EGR cooler. Had a beautifully crafted coolant bypass from BB_Cuda and a nice 15mm stainless machined plug for the exhaust manifold.

Seemed like an easy task and it was, until an M8x28 torx had lost it last 3.5mm and left them in the threaded hole of the exhaust manifold. It was the top #6 in this picture:



Break was very clean that at first I thought it used a shorter bolt. But not, the last 3.5mm were staring at me right from the hole and did not make it by a few threads. Tried making a hole punch for the drilling process, only to have hole punch go dull on me. Drill wondered did not stay on center and nothing happened. Plug was attached with one bottom bolt and allowed me to enjoy a full diesel aroma for a few days.

Engineering minds at work had a hard time figuring out the material of this ghost torx M8 and we still do not know what exactly it is, but it is a very hard steel. One thing I had learned, what the centering drill bit was. Here is a picture, along with the good bolt and the bad one:



Went an got myself a nice set of cobalt drill bits. Equipped with a lot of engineering advice, a set of new cobalt bits and a few centering drill bits I hoped that I would be able to carefully drill out the remaining 3.5mm of the super hard steel bolt.

I did Dulled a few hole punches, even the one made from a broken centering bit. Started with a small centering bit, it wondered and did not stay on center. A small Cobalt drill bit wondered as well. Dremel came in handy. As you can imagine it was a pita to be working in such a tight spot. I used dremel with some hardened milling pieces to bring the drilling spot back in line. Many times, after trying to keep on center. Eventually small Cobalt bit took and seemed to be on center. Used a bit of oil to keep it cool. Of course all orifices were plugged to avoid debris.

First through hole, yay. Next size bit broke. Breakng a hardened bit or a tap is basically, byebyebaby. Luck was on my side, it shattered. Few sizes up, hole larger. Next was the last 1/4" bit. First thing, cracked the end off and it would not drill. Centering bit in the same size finished the job and a nice metal shaving in a shape of a major thread diameter(curled) came out. Yes. M8x1.25 tap carefully finished the job.

Lesson Learned (if you are still here): for these hard bolts when you do take them out and put them back (I did, a few times before). Chase them with a tap and die set to clean the threads...

And now, the ghost bolt with it's logo (under a microscope). Tried to search the manufacturer to find out the material. Still a puzzle.... I think it's from Mars... Any takers?

[Yozh]

Here is the modified EGR in case someone is wondering. AAR Race Pipe looks so much better though.

BTW, the in and out diameters on the OEM EGR are quite different. We discovered it when doing a tiny 400 micron port through. In was 54.35mm and out was 51.5mm. Wish I could have ported it, but the intake manifold is the stopping point right now.

[TDIwyse]

Great war story. Amazing how something like a busted bolt can turn an easy job into a nightmare.

[WreckerX5d]

Originally Posted by TDIwyse

Great war story. Amazing how something like a busted bolt can turn an easy job into a nightmare.

Yep. Once stripped the Allen slot (fuck allen) on the top of my rear shock, took a good amount of time getting that nut off and ended up dremeling a slot for a flathead to go and keep it stable.

I hate stripped bolts. Have you tried those bolt remover things they sell at Lowes or Sears, Yohz? They worked for me.

[335dsleeper]

Originally Posted by TDIwyse

Great war story. Amazing how something like a busted bolt can turn an easy job into a nightmare.

1+ And it always happens at the worst time

[BB_cuda]

So sorry to hear of this struggle. I was hoping you didn't have to resort to the multiple drillings. But you persevered and got through it. Great job! Glad you and your wife don't have to smell the exhaust anymore.

Coincidentally, I did a plate install as well (wrote about it in the AAR race pipe thread). I ran the new bolts into the tapped hole without plate on to check for any issues. I was making sure the threads went all the way through and didn't stop. The older block off plate I was using utilized the thick boss that the EGR cooler employs. So, I didn't know if that setup has the bolts protruding through back side (and frankly still don't).

As yozh mentioned, the OEM screws are 28 mm long. The new screws Andrew supplied are 25 mm long but his plate is only 1/4" thick whereas the boss is more like 3/4" thick if I recall correctly. The 25 mm screws indeed protrude through the back side of the flange with plate on. I used antiseeze compound on the new screws.

I did note one thing during removal of the older screws/boss block off. The screws took very little effort to unscrew. It makes me think they backed off some. I clearly remember torqing those guys in with the T45 torx bit. I never saw evidence of a leak though.

I did consider reusing the OEM screws instead of the AAR supplied ones. Yozh's event gives me pause as to if I did the right thing after all. I wished I had chased the threads with a tap as he suggests.

[GaryE30]

I had a tense moment a couple months ago. From the factory, the 4 torx bolts that hold the rear bearing carrier & hub onto the e53 x5 rear carrier are permanent loctited in place. With the axle still in the car and mounted they're all but impossible to access. If you unbolt the axle and press it out, it cannot be fully removed unless more suspension components and exhaust are pulled as well. To save time, I just shifted it out of the way for each bolt I tackled.

After shearing the tip off of one of my socket extensions (3/8 drive BTW), I decided to hit the bolt threads with some heat and penetrating fluid. Once the bolt broke loose is when I found that the loctite was there and required 500F to break the bond. After that the job was cake, but prior to it, I was seriously scared I would round a torx head off and have to figure out a way to get a dremel head back there to cut it off. Tense moments.

Another time, I bent a craftsman wrench about 30 degrees removing an oil filter adapter housing bolt from a 4.0L Jeep. It was impressive how tight the bolt was to be able to resist the torque I put on it and bend it about its stronger area moment of inertia.

[glitdi]

It is amazing what hitting a cap screw head with a hammer before loosening it will achieve. It just takes a rap or two and will work wonders on anything cast.