glw165

97 f150 4.6, when started and @ idle sounds really bad, im certain its in the valve train, sounds like rocker arm rattle, i have read a billion post about this, its not the 3 valve motor, its not a exhaust leak, no cop its a 97, new tune up wires and plugs, new maf, new fuel filter, runs great sounds like coming apart, has a cel of heated 02 sensor, and misfire #4 cylinder but runs great, go figure!!

garbill2003

Sounds like a valve or a valve lash adjuster

Rocko1

Get a mechanics stethoscope from harbor freight for $5, pinpoint the noise.

Coachhick

Lash adjusters wear, and do not compress like they should. In the last 6 months, I have replaced all 16 of mine. $9 each at oreillys. Not difficult at all. Drivers side sucks, have to remove egr tube, power steering reservoir, helps to disconnect coil pack and fuel. Need to buy new valve cover gasket. $25 for set. Loosen camshaft cap, do not fully remove, ESP at front, don't want to mess up timing. Remove old, replace with new.....they pop right out, have a partner turn harmonic balancer bolt while you remove the few that we're compressed by cam lobes. Follow torque sequence that you find on google, like 115 in lbs.....25 ft lbs or something.....don't quote that, but I think it's close......... You, a buddy, 16 lifters, valve cover gasket set, torque wrench, craftsman socket set, 12 pack of Bud, and about 4-5 hrs, and your ticking is cured

97 4.6, 188,000 miles............been a certified shade tree mechanic for 8 years.......ever since I unbolted the motor in my 78 f150 to see how an engine worked.