BMW's factory manuals caution strongly about oil in bolt holes -
particularly head bolt holes - for the same reason. Oil, being
non-compressible, is well known as a cause of block fractures. If you coat
bolts with a lubricant before installing them make sure you don't use any
excess, just enough to lightly coat the threads. I'm a little surprised
that silicone did that as it is compressible but if there's too much...
Brian '69 2000
Tampa, FL
http://web.tampabay.rr.com/oilleak/
-----Original Message-----
A strange thing happened to me tonight when I was putting a new water
pump on my U20. When I tightened the bolt that holds the water pump to
the timing cover/block, the part of the block that forms the bolt hole
split off. The bolt was not too tight nor too long. When I took it off,
it came out fine. After inspecting it more closely, I have determined
that there was a buildup of silicone (left over from some other time) in
the back of the bolt hole. When I put the bolt in and started
tightening, the pressure blew out the side of of the bolt hole.
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