Smoking

How long have you beed running the engine? Any oil accumulated in exhaust system needs some time to clear out and it might take a few hours of running.

COULD BE WORN OR BROKEN RINGS/ CYLINDERS

A COMPRESSION TEST MIGHT GIVE A HINT TO IT'S CONDITION

EVEN A SIMPLE VACUUM TEST MIGHT GIVE YOU AN IDEA OF THE ENGINE'S CONDITION

https://www.2carpros.com/questions/2001-ford-f-150-grinding-noise-upon-light-braking

IF IT AIN'T BEEN TAKEN CARE OF OVER TIME, LACK OF OIL CHANGES, "RODE HARD AND PUT UP WET"....ONE MIGHT EXPECT IT NOT TO LAST FOREVER.

.....AND ON THE OTHER SIDE OF THE COIN, THINGS DO BREAK ON THEIR OWN, EVEN STILL, THINGS DON'T LAST FOREVER

IF YOU REALLY LOVE YOUR RIG---EVEN 1/10TH OF HOW MUCH I LOVE MY TWO.

...I'D BE INVESTIGATING REBUILDING YOUR ENGINE OR BUYING ONE ALREADY REBUILT (THIS REALLY CUTS DOWN ON "DOWN TIME")....BEFORE IT GETS "TERMINAL"

THE COOL THING IS: YOU WILL HAVE A NEW VIRGIN ENGINE, THERE WILL BE NO DOUBT WHO IS 100% IN CHARGE OF IT'S HEALTH AND WELFARE FROM HERE ON OUT (NO WHINING ABOUT THE PREVIOUS OWNER)

THE MEDIC

How long have you been running the engine?

Give it more time. You might new a few days to get the oil accumulated in exhaust system to clear out and that requires running the engine for at least half an hour at a time.