Did the 4.0 SOHC engine ever become a reliable 200k mile engine? After what year is it safe to purchase an Explorer with this engine? If the timing chain problems have been fixed under warranty, does it become a reliable 200k engine, or is it good for only another 50k? Do rebuilt engines (like a Jasper engine) fix the timing chain issues or are they about the same as the original engine as far as reliabilty? I would like to buy a late 90's early 2000's Explorer. They seem like a lot of SUV for the money, but I am leery of the 4.0 SOHC engine which seems to be the engine in most of them.