Originally Posted by NoNameJoe
A common mapp torch sold at Home Depot or Lowes for 65.00 will heat up a fastener red hot, enough to make it easier to remove.
Anyone who thinks it isn't cut out for use has no idea what they're talking about. Usually fueled by assumptions about how the gas isn't authentic or as hot as it was x number of years ago. Also people basing the torch performance off of a different propane torch they used or a camping stove, that puts out a weak piddling pencil sized flame. A torch with a good torch head (like the swirl ones that bernzomatic sells) at full blast sounds like a jet engine and delivers serious heat.
Is it as hot as oxy-acetylene? No way. Is it going to cut through metal? Not a chance. Does it get metal red hot. Yes. Is it effective at removing stuck fasteners? Yes.
I suspect the mapp is overkill and propane will work too, just with a longer time necessary to heat it up.
If you hold the mapp torch on a bolt it will turn red hot and glow brightly in less than a minute. If you're not looking to cut through a fastener a mapp torch is more than enough for a home mechanic to use to loosen fasteners.
I've used the same mapp torch on dozens of rusted fasteners, all of them came out like nothing only after I hit them with the torch. I've used it on pipe plugs on intake manifolds, drain bolts on diffs, cat heat shields, exhaust fasteners, it's literally one of the best things I have ever bought. I've used it to remove rusted fasteners on 19 year old cars (and I live in the rust belt) that wouldn't budge with a ratchet alone. I don't even bother with penetrating oil any more.
I was gearing up to post something similar to this, thanks for beating me to it. MAPP gas/quality torch head works fantastic for heating automotive exhaust fasteners. I have been doing it for ~20 years, no one here could convince me otherwise.