I have a 2005 XL with a 4.2, almost 200k miles. On the way home yesterday I was sitting at a light and noticed the engine knocking, I pulled away from the light and it went away, I pulled into a gas station and checked the oil (just changed it 2 weeks ago). Oil was full, and dark, not milky or anything. So I continue on driving home, and it did it once more, but went away after pulling away from the light under load.

Any ideas? Would this be a symptom of a failing oil pump?

If so, how difficult is this to replace? Is it something that can be done easily?

 

Sounds like a failing oil pump

http://answers.yahoo.com/question/in...0004644AAJ4jzb

 

my 05 ford 4.2 did the same thing . belive it or not its the hook on the passenger side thats used to take the motor out ....i had to take mine to the dealer. a week after i got it. push it over so it don't rattle and it will never happen again.