Jhock wrote:
Since this is a metal working group, I have a problem I need help with.
I decided to put a new muffler on my 8 hp B&S aluminum block engine,
the old muffler will absolutely not come out. I have taken the engine
down to the basement as it needed some repainting anyway and have been
soaking the muffler joint with PB Blaster, Tefoil, WD 40 and then tried
some heat with the welding torch, enough to get the muffler stub red hot
but didn't want to do any damage to the aluminum engine part. I have
put a pipe wrench on the muffler and pulled, hammered, etc and it will
not budge. Have cut off the main part of the muffler so there is about
1 1/4 inch stub remaining. May have to carefully grind slots into it in
about 4 places where it threads into the engine after cutting it off
flush, before I go to this extent does anyone have any experience with
this type of metal seizing. Sorry for the long post.

Jack
Assuming the muffler is steel, you might (after stripping the block
down) use acid to dissolve the steel. Acid does not attack aluminium
(but alkali does).