My 97 5.4 with 127,000 miles has a knock at startup that began at 93,000 miles. At first only when cold outside but now it knocks at startup even during warm weather. It only knocks after the engine has sat for 10 hrs or more. Is there something besides PS causing this that I can check? If it is PS I'll just keep driving it but if its a lifter or something easier I might tackle it. I've never seen the valvetrain on one of these engines but the book pics make it look complicated. Would a lifter be an easy fix like on an older engine? I'm guessing it wont be as easy as on my 1956 ****** F-head. I'm using Amsoil filter with anti-drainback valve.

 

what kind of oil filter do you use? if it has a crabby drain back valve it may take the oil a few seconds to reach the top end of your engine. it could be valve noise til it gets there. just one thought

 

I agree with racerf150man that it could be your filter. However, my 2000 F-150 with the 5.4 also makes a rattle at startup and the best explanation that I can find is that even with an anti-drainback valve that as the pistons wear (even if it's only micrometers) there isn't enough oil staying in and around the cylinders to compensate for the extra movement of the piston and thus not preventing the rattle. I have been told that if I were to use a heavier weight oil that it might help but thus far I just change my oil frequently and listen to make sure the rattle doesn't become worse.

 

I run an Amsoil filter. I've tried the heavier oil and the noise seemed the same. I've thought of a pre-luber but don't think it would help because I get oil pressure immediately but the knock will last for up to 2 minutes.

 

Since you don't have an accurate discription of what knock is, there is no way to guess at it from hear.
Bearing knock?
Spark knock?
Loose pully?
Loose alternator mounting?
Exhaust system banging?

 

if it sounds like fluttery type of ticking almost (not liek pcv but faintly ticking) type noise and goes with engine rpm, i think your fine my 00 5.4 has been doing it for over 40k now and it seems the longer i let it sit the more it does it. its always gone after a few min of driving and there has been no issues with the truck (except high idle which i have fixed)

 

It's important to be accurate in discription.
A tick is not a knock.
I would say look at the possibility of an exhaust leak at a manifold or a pipe close to the engine.
It would be heat sensitive and tend to close up with heat.
As the leak gets larger, it will take longer to go away until it can't seal itself any longer.

 

i'd go along with bluegrass here...as it gets warmer it goes away....classic exhaust manifold/pipe problem...zap!

 

Thanks guys. Its not a light tick like a standard lifter noise. Its more of a heavier knock sound that does correlate with engine RPM. From under the hood I can't pinpoint the noise. Seems loudest outside the truck standing next to the passenger side front tire. I've checked the exhaust and didn't find anything obvious. I'll check it again though. I'll check the plugs too.

 

let us know what you find out...zap!

 

If it's ps you are out of luck. The 5.4's have hyperutetic pistons and if not sized to bore will slap. Add a wrist pin mounted too high in the piston and you have ps. A heavy knock is a main worn out.It won't go away with temp