I have a '97 Ranger with only 123K mls which I just purchased and it has a tapping noine around the lower rear right side of the engine. I took it to the dealer and they said it sounds like piston noise. I was told that Ford had redesigned the piston for the 4.0 to correct this noise but don't know what years this was done in.
Does anyone know which yrs have the redesigned pistons as I'm planning to replace this eng with a used one and want to get one with the redesigned pistons.
Tks

 

I know 98-2000 really have this problem, unsure of when it started. My engine makes this "marbling noise" and is still running strong at 148,000 miles. The noise is due to the wrist pin location being offset so at TDC there will still be a rotational force on the crank.

 

I have the exact same noise in a 2000 Ranger 4.0 engine. 2 Ford techs. said to just drive it, it's normal! Kind of annoying but that is what I am doing. I only hear it at slow idle, especially when engine is cold.

 

the noise is coming from the push rods and rockers geting war out they have poor oiling and their for wear out fast. my truck does it sense ive got it at 60k miles it has 135k now and still has the tick.. to fix this tick delta cams had the new rockers and pushrods for 200 i bleave