I recently came across an article about the dangers of getting brake cleaner hot. A mechanic had used brake cleaner to clean a part prior to welding it. Unfortunately he did not get all of the cleaner off of the part. When he was welding he noticed the brake cleaner "puff" a bit of smoke into the air. Of course he inhaled some of it. He almost passed out and barely made it outside for fresh air. The cleaner had released some very toxic fumes (phosgene) that attacked his nervous system within minutes. The article is too long to post here but if you want all of the details follow the link below.