I'm lost. Got a lot of things fixed on the beast but not this yet. Loud noise spuratically. Sounds like I'm driving a garbage truck-literally. 97 5.4L 4x4 expedition. Seems to occur more often when the engine is running in hot weather 90+. But if I romp on it the noise goes away. Depending on how long I've been driving depends on how long it takes the noise to go away. Again, it sounds like the biggest baddest beast ever when this noise kicks in. It's not, it is totally stock. 185,000 miles. Purchased 2 months ago. If I park it when it's making this noise, it starts up and makes the noise. If I park it not making noise, no noise when i start it back up. If I rev it up to about 2500 rpms and hold it for about 4-8 seconds the noise goes away. Idles awesome at about 700 rpms but if I hold it down at about 1500 rpms seems to have a miss. Just passed Texas state inspection today with emissions. Was throwing the P0401 and P0402 codes simutaneously. DPFE sensor and hoses. Still makes the noise. Cleaned the tb. New radiator and thermostat. Looks like previous owner installed new water pump. Cooler weather it takes a while before it starts making noise and doesn't last very long. RPMs dont fluctuate. Doesn't seem to lose speed or power. Noise increases with accelerator. Sounds like "limp" mode but I don't think so, doesn't really lose power. I'm thinking exhaust?

 

Inspect the EGR tube that runs from the rear of the driver's exhaust manifold up to the EGR valve for breaks or holes.

 

Did that when I was diagnosing the P0401/2 codes. It's in good condition. It was pretty hot in Texas this afternoon 90-95. Drove home for about 25 miles and it made the noise almost the entire way home. No engine light either. This morning was pretty cool 75-80 and it never did it. It's got to be something that is sticking in hot weather. Like I said if I park it when it's making the noise it starts back up making the noise. If I park it when it's not making the noise it doesn't make the noise when i start it back up.

 

No one has any ideas for me?

 

Have you used a mechanic's stethoscope? With a noise that noticeable, it shouldn't be hard to isolate to block or exhaust.

Could it be the famous passenger side exhaust manifold cracked or warped? Haven't heard it being a major issue on the earlier 5.4 Tritons, but it's possible.

 

Ok I'll check that out more carefully...it's so loud though it should be throwing a code. Would it be possible for the egr vac sol to be bad and not throw a code?

 

If it's a mechanical break and not an electrical one, then yes.

 

got a video clip we can see ?

 

Not sure on this but I'm think your engine should be the triton 5.4. Just not sure when they strarted using them. But have you checked the cam phasers. They are notoriously noisy. And almost sound like a low oil tick. Mine on initial start up doesn't make noise but when it warms up it starts making noise. Just an idea hope it helps

 

My first thought was cam phasers also. Try running some octane boost or fuel up with premium and see if that has any effect.

 

2v's don't have cam phasers...

 

Wasn't sure if they did or not. Thank you for clearing that up.

 

a little late to the party here ...

sounds like the cooling fan clutch kicking in.

when the temp comes up, the viscous clutch for the fan kicks in and she'll howl like a banshee. rev it up and the fan starts pulling air through the radiator, the clutch cools down and disengages, and the howling stops.

sounds like the fan clutch might be engaging a little earlier than it needs to, perhaps. but it appears that it *is* working .....

my old explorer would do this as well, but only in hot weather with the AC on. if you idle for more than a few minutes, there would be enough heat in the radiators to get the fan to kick on. after a few seconds of higher engine speed it would release ... exactly as you describe.

i'd rather have one working too much than not enough.... not sure you have a problem to fix with regard to the noise.

 

Sorry have been busy-I think you r right on. There seems to be no ill effect when driving and it starts making this noise. Might take a little longer to shift and a banshee is good description of the noise.

 

I was going to say fan clutch. Yes the expedition has a fan that makes it sound like a big diesel fan pushing wind. Perfectly normal. As the truck gets hotter the clutch will lock down and blow a huge amount of air. This is really noticeable at a stop light in 100+ weather. You'll hear the wind pick up as it idles, then when you go to take off, the clutch is still locked and everyone's looking for the detroit under your hood.