On my 88 f150 5.0 , while cold on at least with in the first 10 or so miles it runs great sounds great, but the longer i drive i get a knocking sound just while cruiseing . but it doesnt do it under a load .... when im in the driveway i can put my foot on the break and gas it up no noise but go down the road and it has a slight knock noise... never gets any worse , still has good throttle response . but its only at level speed driving ? any ideas?????? its only got 85000 miles , it has had a new tps, temp sensor ,oil pressure sensor put on.

 

Sounds like a rod knock.

 

i thought if a rod was kmocking it would do it more under a load?

 

they normally do, iv never heard of them not honestly....only thing i can think of is a U joint is going out and the bearings are binding up inside. my f150 would make a popping/clicking sound from 2mph-40 or so. i dont really know, its a good place to look since u joints are cheap.

 

No. Like pulling a trailer, when you unload it by stepping on the brake it bangs forward and back on the hitch. As long as you're on the gas the trailer doesn't bang around.

 

sounds about right. the last one i killed, it was fine as long as i was in it, but when it was in overdrive just cruisin, it knocked. but as long as i was givin it some gas id never hear it.

 

sounds more like a main bearing to me. once the oil gets thin, it starts knocking. is it more of a deep knock, or a ticking type knock? is auto or stick? if its an auto, check your tq convertor bolts. sounds stupid but ive seen them come loose more then once and make it sound like its knocking.

 

It's a automatic c6 actually..... It's not a deep in the pan sound more like a constant spark knock , but only at level speed .... I drove it 35 miles to work today ... Good temp, oil pressure, no smells, no lights and 15 miles of that was about 70 mph on the interstate..... Already checked u joints look fine no wobble at all... Still idles good .. Starts up great.. Nothing under a load just don't know....?

 

look for metal shavings in your oil. could be a rod or a main bearing.

 

Just had the oil pan off ... Had to replace oil pump ... But it was because of a bad gauge in the dash.... Went ahead and changed pump , while was in there saw no brass or shavings ..... Had the same noise before ... I thought then rod or main ... ..... Could injectors cause this mpg are lower than it should be runs good but sort of sluggish from time to time ?