Jeep Repair...

any time these three word are together "very loud knock" it is not a good thing! you really dont want to drive the car untill someone goes in and finds the real reason. 59000 miles is low miles for the type of problem we are talking about but it is possible. If you drive the car and the crankshaft or rods come apart you will have no choice but to replace the engine. So make friends real quick with a good engine mechanic. If he can go in and fix it before failure occurs it may only cost you half of what a new engine would! You may try to go cheap and get a used engine but you never know the past history of it so it is a gamble every time. Since you say that it has already had rods, oil pump and timing chain, whomever did that work really did not go far enough and get to the real problem. They should have! If they got far enough into the engine to replace rods or rod bearings they were already there and the only thing left is crank and bearings. they should have been able to take some measurements at that point and make sure the crank and bearings were ok before putting it back together. I would think that they would be willing to fix it right and defer some of the labor cost because of their missed diagnosis.

i have a 04 liberty 3.7L and I have the same issue! I got the car from a woman who sid it was fine other than O2 or catallitic converter but it has been nothing but issues in the 2 years Ive had it... We have replaced just about everything until I heard the knock... I was wondering what the best replacement is and what engines to trust?