1999 Ranger 4x4, 4.0, 5 speed manual. 174,000 miles. New heads three years ago by a certified mechanic.
Cold start no noise. Once engine gets to operational temp, lifter makes rattle. Accelerate or under load, rattle goes away. Can the noisy lifter be changed out without pulling head? Rattle doesn't seem to be getting worse but at cruising speed, rattle is prominent....until acceleration.

 

I don't know if I can be much help here, but there are some questions the answers of which could have some bearing on a possible solution.


Oil changes , how often and where ?

Mileage at time heads were replaced ?

Have you considered having the oil pressure checked or can you tell us what it is at idle and higher RPM ?


It is important to know how it was determined to be a hydraulic lifter?
Because there are several things at play here , it could be a mistake to go tearing into something without being sure of what you are after, just trying to help save you some $$$.

 

Oil has been changed 3000 miles with high mileage synthetic. Heads were changed at 159,000-ish. Have not checked oil pressure with gauge, but dash gauge shows normal and steady at idle and 2000 plus RPMs....5th gear at 70 mph.
Not sure on the hydraulic lifters...seems that 1999 4.0 is according to google.

 

I think there is more going on than a "lifter" !
Was any timing chain work done when the heads were changed?


Without actually hearing the "rattle" , suggest you get at least 2 estimates of the noise by 2 different shops .

 

Yep, your 1999 4.0 is the OHV Cologne engine. What weight motor oil are you running? Oil pressure increases as RPMs increase. Just may be fine with a slightly heaver weight oil due to age/wear.

 

The oil I have been using is Valvoline 5-20 syn. No timing work was completed when heads were replaced.
I have an appointment with my mechanic...starting to sound like it's getting way over my head.
Thanks for the input!

 

If you would , let us know what your mechanic feels is the problem. He will have first hand knowledge since he will be able to actually hear the sounds. Thanks.

 

FYI...Your engine model year calls for using a 5W-30 motor oil. Regardless of being a conventional or any type of synthetic, the 5W-20 is too light of an oil to maintain the film strength required to eliminate metal-to-metal contact.