Ford Repair: General Question, vacuum line, inexcess

Question
I have a 98 ranger that has low pressure in the #6 cylinder the pressure is 74lbs and I was told by a mechanic that the only reason the pressure would be that low was if there was carbon build up on one of the valves in that cylinder. So is that true and is the only way to fix it to have the heads redone? becuase it is a very expensive repair and if that is the only way to fix it what would happen if I did not get it fixed and kept driving my truck? Because it is very hard to save money when you have a family and the only one working.

Answer
that answer has two possibilities. yes, excess carbon build could cause this but, you would see lower than normal compression readings on the other cylinders as well. if this is the case, your local ford dealer can do whats called a carbon induction service. a cleaning agent is ran via. a vacuum line into the intake of the engine. the chemical will clean the valves as it enters the cylinders. or your local tech can go old school and actually run water through this same line and drive like crazy up the highway ( strongly recommend this is only done by a professional though, not done properly, damage can occur ). the other and most likely concern is that the valve seats on this cylinder have been pushed back into the head from the valve opening and closing so many times. it was a design/material error in particular years. yours being one of them. i don't recommend driving long term with this condition, long term meaning a vacation across the country or inexcess of another 7500-10000 miles without getting it repaired. what can happen if you continue, long term you will clog the cat converters from exhaust quality leaving engine. you will foul spark plugs quickly. good luck and keep me posted  . -b-