What causes high speed rattle noise on front of engine. Main timing chain tensioner failure. In order to properly repair engine must come out. And a $200.00 tool kit is required. ($360 for the master Ford cam tool kit) $400.00 timing chain kit as well. If u have a 4wd, chances are real good that you will have a balance shaft and chain. If so the block girdle and oil pan should be removed. I highly recommend a complete engine gasket kit. There are "tricks" on the Internet to cheat. But as complicated as the chain system is. I suggest you dont cheat. Also the jackshaft bolts are torquetoyield bolts (one time use) both bolts are not included in the timing chain kit. Been able to get bolts from Ford as well as Amazon. Another tip, scribe a timing mark on each cam shaft with matching mark on the first cam cap before removing old chains. This will help reassure you that they are lined up right on TDC of #1 cylinder after reassembly. Right hand cylinder cam shaft bolt is reverse thread. Torx tool kit will be your friend. T30 T55 (I think)... and inverted E12 will be needed. If doing these chains might be out of your league , or getting the special tool kit is not an option.. these motors are available rebuilt in the $3,500 $4,500 range. Some are offering 3yr unlimited miliage warrenty.