'97 250HD, 351, 70k...if i start it and take right off it's pinging/tapping, if i let it idle for a few minutes first it's fine...obviously i'm no mechanic...what might it be? weather/temp doesn't seem to matter...
its possibly piston slap in its early stages,or a noisy lifter.Hard to say from where i am without actually driving it,but thats my guess,does it do it worse under heavier loads,or as it revs up does it get louder,like right before it shifts to the next higher gear?
Could be a problem with the computer controlled spark advance. If a sensor is bad or a vacumm line unattached then it may be sending a bad signal when cold. This could cause a wrong advance curve and lead to pinging.
Just brought a 90 f250 with a 460 5 speed 2wd. my 96 f150 with the 302 5speed 2wd made the same noise. Its a lifter noise, but from what my mechanics tells me it usually doesnt happen to around 100k. Just let it warm up a few minutes. If it persist or bothers you, switch to a higher vescosity oil,or use an additive, like stp.
"Snowflakes are like pennies, by themselves, they aint much, put a whole bunch together, now you got something".
Atco, New Jersey