I have a 1998 ranger 2.5L engine. I took it to a Ford garage and they told me I have a rod knock..........I took it also to a good mechanic and he said the sound is coming from the lifters.
There is 172000 miles on motor and the noise started at 131000, and is getting worse. Should I drive it till it blows, or is there a way to tell what the problem is? Thanks for your response. Tom

 

As a rule of thumb, valves and lifters clack and clatter, connecting rods knock. An engine with noisy valves can run quite a long time whereas a bad connecting rod usually fails quite quickly. My best guess would be that your mechanic is most likely right as 41,000 miles is a long time for a bad rod bearing to last.

 

Lets think about this some more, you have an over head cam, not a pushrod engine, so the lifter noise diagnosis makes me suspect that the Tech isn't familiar with your engine!!!!

So, listen to this engines noise & tell us if it sorta sounds like yours,
2006 Ford Ranger 2.3L Duratec engine problem noise, Broken timing chain tensioner - YouTube, if not, look through like engine recorded noises on You Tube, or the like & post a link to the one that seems most like yours.
Generally, rod or crank shaft knock noises are lower frequency thunks or clunks, coming from low down in the engine, while valve train noises are usually ticks, clicks, taps on top of the engine & chain driven OHC engines with problems with the chain or tensioner, will usually be noiser toward the front of the engine.

Use a mechanics stethoscope, or fashon one from a length of tubing, long screw driver, or broom handle, one end to your ear, the other end on the noise suspect & tell us where its loudest & what it sounds like..

More thoughts for consideration. Let us know what you find.

 

My '86 bronco ran for 4 years with a slight rod knock.. finally blew when climbing up a long grade(for the 8th trip)..would knock hard when cold for a second or two until oil pressure came up