The flame trap is located in the Positive Crankcase Ventilation (PCV)system and is the "breather" for the lower crankcase. Sometimes referred to as the "spark arrester", it "filters" by catching by-products from combustion in the filter (plastic - or metal on older model 240's). Flame traps can get clogged or gummed up with oil and residue over the years, causing pressure build-up in the crankcase. Over time, this can cause the main seals to fail at the front or rear of the block (any constant oil drips on the floor of your garage?) and over time blow-out your front and/or rear main seals!

I had a 240 that leaked a little oil from the front seal. I cleaned the flame trap and the leak stopped. ($2.00 for a new flame trap versus a couple hundred a shop would charge in labor to replace a $6.00 main seal) - no wonder the mechanic said you didn't need one!

Hope this helps.