I have a 2001 Expedition with the 5.4.
Yesterday I noticed when i started the expedition there was a knock coming from the engine compartment. I got out and it was coming from the passenger side and lasted for about 30 seconds.
This morning i noticed it again except it was louder than yesterday . It lasted for almost a minute and then it quit.
Could this be piston slap or something else. Running the recommended 5w20 and changing at correct intervals. The truck has 10,700 miles on it.

 

I have a 99 Expedition, with just under 15,000, just started hearing the same thing. Only does it when cold, as soon as the temp gauge starts to move it quiets. Almost sounds more like a lifter noise, light tapping. Hope its not the dreaded Windsor 5.4 piston slap, hate the thought of ripping the engine out to replace it. I thought the 2000's and 2001's were fixed, guess not..

Dvds

 

If it clears in 30 seconds, it's not piston slap. The reason you quit hearing the PS problem after time is that the piston has time to heat and expand. This can't happen in 30 seconds. Sounds more like a hydraulic lash adjuster is leaking down when the motor is off and it's taking a little bit to pump up. At least I'm assuming that the OHC engines use some sort of oil fed lash adjuster so manual adjustment is not necessary. Many other cars with similar cam arrangements have the same problem. The adjusters will bleed down and require a short period of time to pump back up. There is a small check valve in them that should maintain pressure. If this is happening on this new of vehicle, I'd consider having it replaced (the HLA) as this just isn't right. On older vehicles, the key is clean oil to keep their very small passages clean and clear.

 

Irutt problem may be the slap.. I see
he lives in Texas and chances are the
mornings are probably quite warm.All of my
piston slappers all started with the
30 to 1 minute noise, I sure as He**
hope its not PS on a 01 motor.
Irutt, if you have been putting in 6
qts on your oil changes, try putting
in 6.5 qts.....Good Luck

 

Does the 'slap' occure under load, no load, light load or??? What I'm hearing only occures under light load, and not even every time at that. I never hear it when I first start, only once underway.

 

I don't have the problem on my truck (yet). When I change I fill right to the full mark. Almost 7 qts on my engine. As for the slap noise, my wifes car makes that racket for about 30 seconds after start, the lifters pumping up. Once up, no problem. I've had several motorcycles (air cooled engines) that need a little more tolerance in their build some times. Those were classic cases of piston slap. It would take several minutes for the piston to heat and expand enough to take up the slack. It is impossible for that to happen in these engines in 30 seconds. There is no way the piston is going to expand that much that fast. I know some of the posts in the piston slap section talk about guys that start up, back out the drive, go several blocks etc. and still slapping, now that would be piston slap (or a rod). The way these hydraulic lash adjusters work though, sitting way up high in the head like that with constant pressure on some of them, they are prone to leak down some and will take a while for oil to get up there. The passage ways that let oil into them are very small. That has been the fix on some cars, retrofit the HLA's with ones that have slightly larger openings. Doesn't prevent the problem, just allows them to fill back up with oil a little faster. Personally I'd like to find a way to keep our engines from revving to 2k at first start up. No reason to go over 1k at start. I heard some guy talk about wiring in a bypass on his IAC but I haven't heard back from him on that. That would also help some, you wouldn't be pounding at hi rpm's on those cold lifters.

 

Thanks for the replies. Yes it is not really cold here in the mornings, 70 -75 degrees. Yes! I hoping it is not piston slap and just some mild problem that is easily remidied.
When i start the engine i get out and run around to the passenger side and listen. You can hear it when the engine is at high idle. It really is noticeable after the engine idles down, and persists for about 30 seconds. I am taking it into the shop on Tuesday to have it looked at. Will keep you posted on their diagnosis and prognosis.

 

Mine did the samething, except mine wasnt piston slap. The dealer said that the noise was caused by the bottom end of motor being damaged. They said what caused that damage was low oil pressure on higher rpms. So they replaced the motor, and so far no problems......