Well my truck, 1996 F150 5.0 2x4, has had a knock for probably about one and a half years now but driving it every day it has always ran great and had plenty of power. The knock has never gotten any worse since it started. Ive put new lifters in it and everything is fine in the top end. The knock is loudest when you let off the gas and slow down. Has anyone every had this problem with their truck?

 

Lots have had this problem & it usually lasts 1 and 1/2 minutes, sometimes 1 and 1/2 hours before the rod leaks out of the block. This thing still firing all 8?

When it does come down, it's time for a full rebuild, not just fixing this knock.

You ready to replace or rebuild?

 

Yeah like I said it runs great still. If it was a rod bearing wouldnt it get louder at higher RPM's under load?

 

The knock follows engine speed, right? Perhaps just a wrist pin.

You have checked for anything external, right?

 

Yeah it does. Its definitly inside the motor. Just trying to get some opinions on what it could be. Started one night going a little too fast with overdrive off lol.

 

Only a teardown will tell.

I'd just line up a replacement and do it that way.

 

mine had a loud knock and it was checked out this morning, the mech. thought it was the crank, when we removed the srp.belt and fired it up it ended up being the airpump,,it pays to check very good before rebuilds,,saves a lot of money