2004 Ford F150 Noise

You are correct, it doesn't have one. Can you tell aprox where the sound is coming from?

The noise appears to be coming from the rear of the engine or front of the transmission. Sometimes it is loud enough to be heard over the radio but not often. In another car a very similar noise turned out to be a speedometer cable.

The only thing I can think of is if the sound is coming from something loose on the exhaust system. As far as the engine is concerned, there isn't anything that I can think of in that location that would cause that type of noise.

After more listening it may be coming from the front of the engine, it is hard to tell and being intermittent doesn't help. I tried rolling the window down to hear it but could not hear anything reflecting off of the curb. I had a 1977 Oldsmobile that had a similar sound and it turned out to be the speedometer cable.

Have you checked the accessories that run from the serp belt, water pump, alt, PS pump...?

The noise is getting louder and more constant. How do you check the alt., PS, water pump, etc., when you cannot even see these items while the engine is running much less touch them. There is no noise when the engine is idling.

You need to remove the serp belt, start it for only a few seconds to see if the noise is gone. If it is, start spinning the accessories' pullies to see if any make that sound. NOTE: Only run it for a few seconds to see if the sound is gone. Without the belt, it will overheat.

I put the pickup on jack stands, removed the rear wheels and ran the pickup up to speed. The noise seemed to come from the rear area of the truck. The brakes are new and not dragging. The U-joints seemed to be good with no slack. The noise is like a piece of tin rubbing on the drive shaft but that is not happening. It doesn't sound like a rear end gear but I am stumped since it is coming from that area of the vehicle.

Have you checked the pinion bearing and the axle bearings? If the sound is in the back, there really isn't much more.

Let me know.

I had the u-joints, pinion bearing, and rear wheel bearings checked out by a mechanic and they all appear to be in good shape. The pickup still runs as good as ever and the noise is still intermittent.

The noise is more consistent and louder now and I believe it is coming from the differential. I am taking it back to the Ford house to get it checked out and will let you know what I find.

Yes, let me know what you find. I feel it has to be a bearing, but without being there, it is hard to tell.

I took the back cover off of the rear end and inspected the gears and they appear good, replaced the rear end fluid with new synthetic gear oil with recommended weight in owners manual. The noise is still there but at least I feel better about the rear end. I will continue to search for the problem and keep you informed.

The noise definitely has a relation to the engine speed and mostly occurs while accelerating but now I can hear it while slowing down sometimes.

If the noise is coming from the differential, my guess is the pinion bearing. Is there any up and down play where the u-joint connects?

There does not seem to be any up or down slack or play in the pinion bearing.

Did you check it with no tension on the driveshaft? In other words, was the vehicle in neutral? If you are sure the noise is from the differential, the only thing left is to take it apart and check the bearings.

Let me know what you find.