when I start my f250 when it is cold it knocks for a few seconds and stops when it gets warmed up andI start it no noise what can this be truck runs great good oil pressure and no over heating issues
Model-Year ? Engine Option ?
CSA
A lot depends on exactly what the “knock” sounds like. Unfortunately, we can’t hear it.
One possibility is piston slap, which is harmless even though it can be annoying. However, I don’t recall any Ford engines being subject to piston slap.
It is also possible that your engine has lubrication issues.
It would be helpful if we knew the model year, odometer mileage, type of engine, and the maintenance history of the engine.
it is a 2002 with 114,000 miles 5.4 gas engine
Donn, I Tried Finding Any Ford TSBs (Technical Service Bulletins Written For Ford Technicians) That Pertain To Your Vehicle / Engine And A Cold Start “Knock”. I Didn’t Find Any.
However, one bulletin addresses “some vehicles equipped with the 5.4L 2-valve (non-supercharged) engine.” The 1999 - 2004 F - Super Duties are included in a small list of vehicles with this engine.
THE BULLETIN GIVES NO AUDITORY SYMPTOMS so I’m just throwing it out there and don’t know if it could cause anything that sounds like a cold-start knock. Maybe others could give opinions on this matter.
The bulletin explains that some of these vehicles use stainless steel exhaust studs and sometimes they break (" . . . may exhibit broken exhaust manifold studs").
The fix is to replace the exhast manifold, mainfold gasket(s) and all new SS studs and nuts on the affected bank. Apparently the studs and nuts are new revised parts.
I don’t know if this has any merit. I’m not even sure you’ve got SS studs. That’s all I’ve got for now.
What does anybody else think about this creating a cold-start “knock” ?
CSA