My 99 XLT 4x4 SCREW 5.4L has some sort of a knock when i first start it. Doesnt sound to me like lifters. It makes this noise, which you can only hear with the window down when i first start the truck, and lasts until the engine warms up(depending on how cold it is, the longest it does it is ten minutes). As it warms up the sound gets weaker and weaker until you dont hear it at all. If engine is warm when i start it, no knocks whatsoever. Does anyone have any suggestions what is causing this?

 

My 92 (300) just started doing this in the last day or two so I am also interested in responses.

My symptom definately sounds like knocking, but it only lasts a couple of seconds after startup. If the vehicle has been started and running, turned off, then restarted within a short time frame - it will not happen.

Only when it has set for a while.

Mine also takes a at least 2 cranks to get started after sitting. It'll turn over and over and over...but won't start. I turn the key off and try again and it comes right up; albeit with this knocking for a second or two.

 

Mine always starts fine the first time I try. If your knock is only lasting a few seconds then i would say it is not the same as mine.

 

Welcome to the world of piston slap. Too loose skirt to bore clearance and too high a wrist pin. Been in 5.4's since 1999. Ford won't fix it without a lawyer. Ford 5.4's, paperwieghts to hold down hoods at junk yards

 

I have a 1998 ford e350 5.4L 178,000 miles.
I have the same knock when starting while it warms up.
the winter is worst for the knocking.
the engine runs great otherwise.
I think it could be piston slap
I usually run 10-40w oil in it.
I am thinking about using 20-50w to see if it helps.

 

I had the same problem but only last a few seconds, only happens when the engine is cold in the winter. found out it was my fan belt tensioner. no clangy noise no more, my advise is start with cheap parts first.

 

my 98 4.6 does this too. not when its warm, only on cool/cold mornings for 2-3 seconds tops. its been doing it for about a year or so. does this cause any damage to the engine?

 

check your belt tensioner. thought mine was fine so i replaced it anyways and my noise stopped. bearings in the tensioner was going bad.