Hi

My truck has recently developed a bottom end knock .... You almost can not hear it from engine compartment but can from the cab/behind front wheels.

The knock goes away about 2200rpms. The knock is worse for the first 5 seconds or so after starting(kinda makes me thing oil pressure). The engine runs smooth and makes good power.

Disconnecting VCT= no difference. Flex plate looks good from inspection plate. Exhaust studs look good.
5w20 motorcraft oil and filter look good.

Any suggestions on path to diagnosing this problem?



2008 F-250 5.4L

 

Doesn't sound good OP. I'd climb under it with a good sized chunk of heater hose as a makeshift stethoscope and make sure it's coming from the bottom end though. I've had piston slap since my 99 was new and it doesn't sound like that.

 

Any chunk of wood will work as a "stethoscope" a short piece of broom handle is what i use, makes it easier to place and listen to isolate a sound source