knocking noise in cold engine

[Guest]

I own a 2000 ford expedition (5.4 engine) with 64 K on it. I have noticed recently that the engine makes a knocking noise just after I crank it and drive it for the first 3 to 4 minutes. I am suspicious that it might be a rocker arm or piston. Anyone want to take a stab at it?

 

[PBH]

Could be piston slap, butthat normally also shows up at low rpm (esp idle). Probably valve noise. Try listening with a stethoscope, you should be able to narrow it down that way.

 

[Guest]

you own one of the motors that is prone to piston slap. I have never heard it but those who have say it sounds like a diesel motor but then goes away. It won't harm your engine if you do have it as there are many that do with many miles on their motors. I doubt it is valve related as there haven't been many problems if any.

 

[monsta]

What weight oil are you using?

How old is it?

What brand filter are you using?

How often do you change it?

Piston slap, yeah, but that usually is right from the beginning. Is the sound new?

 

[Guest]

I have a 01 5.4 in my expedition and have the same noise. it sounds like a friggin diesel for about 30 seconds. i dont recall if it made the noise when i bought it used 4 months ago with 21k on engine. i changed the oil and used 10-30 with a mobil 1 filter and someone said it makes the noise cause i didnt use 5-20 wt oil as recommended.

 

[Guest]

I just switched to 5-20 wt oil and the cold knock is gone....

 

[ericnj75]

i was reading about piston slap ant the tundra had the same problem and they found that it was a bad ground strap. has anyone heard of this

 

[ericnj75]

i have a 99 4.6L do they have the same problem as the 5.4L knocking.