I was quite annoyed the first time i had to do this job and it caused a big delay in doing a very necessary repair.
When doing my E70 I realized a very small half moon notch in the intake manifold would be enough to gain access to the blocked bolt. I would have absolutely done that without a second thought if not for turbo boost consideration. Fast forward to now when I'm replacing a whole N55 motor in wife's car.
I had the advantage of two motors: blown and replacement. I can test my theory on the blown motor!
I did and no problem!
Pics or it didn't happen:
I used my "finger sander". OFHG removed for clarity. I was able to make the half moon before removing. It would be easier with a carbide rotary tool or a drum sander with a Dremel.
The carved volume did cut into the seam but not through to the inside.
I didn't bother with smoke test i covered the whole carved area with JB Kwik
Another angle
Showing access with long extension. Impact set to "hand tight" I torqued to spec after
Close up. 8mm spline fit better than the E10 (IIRC).
Top view of the bolt head showing full access to the bolt.
My motor has about 120k on the clock and I'll be doing the identical upgrade to preemptively replace the OFHG before it blows.
The post-mortem in wife's motor looks like the OFHG blew catastrophically and loss of pressure starved rod bearings in seconds. I'm planning on that being the only time that ever happens.
–awr–
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