1997 F150 4.2 Need Help! - Ford Forums

Hells · 03-11-2008, 20:21

OK first off my truck has 80000miles. My problem is there is a knock somewhere at first it seems where you put oil in if I go under truck seems under there somewhere. It knock during idle and when accelerator is pressed not when driving and no gas is applied. It does this about 90% of the time other 10% doesn't knock. Any help I can get would be appreciated thanks!

countryboy006 · 03-20-2008, 21:02

hey couple questions for ya is the knock a higher pitch tap or a deep thud and dose the knock speed up with the engine? did this knock occer just all of the sudden or was there a event leading up to it

BigWheelsRolli · 03-27-2008, 12:56

Several things can cause the knocking. Low octain gas. Not changing the motor oil and filter every 3-5 K miles.

Ford used hydraulic lifters for the engine oil circulation. When at low idle the oil pressure will drop causing a tapping sound. Inside the engine there is an oil pump, a lifter piston at the bottom, the lifter rod and a the rocker arm at the top. If my memory serves me well. Any of these can cause the knock. Engine rebuild or replacement may be your best bet if the gas is good and oil is clear.