daveborg98

I have a new to me 2005 F150 4x4 Lariat 5.4L SuperCab with 150,000 miles. It recently started making an odd sound when I take off (only under decent power). It is a progressive ticking that goes away once I let off the gas and I cannot hear it a cruising speeds. It sounds like it is coming from the back of the vehicle. I have attached a sound recording of it as well.

Any ideas?

Martian

What diff do you have?

daveborg98

I am not entirely sure the part number or anything but I believe it is a 3.73 LS Semi-Floating (according to the B6 on the door sticker).

Martian

If it's coming from the back under load, take off the diff cover and have a look at it.

Point is to replace the fluid, but since you'll be doing that anyway, might as well open it up and have a look

daveborg98

I will do that. I did not think about changing it yet but that brings up a good point. I will let you know what I find and if that corrects it.

daveborg98

Replaced with Royal Purple and tested after doing several (about 10) figure 8's. The noise is still there with the same intensity when taking off. The gears looked good with even wear and the old oil was not horrible either.

It seems to be more in sync with the speed of the drive shaft than anything else. With that, could it be more the slip joint causing the noise? It seems to only do it when taking off under quite a load only as taking off easy does not cause the issue. It seems to me that this may be more likely the case as the rear end will squat when taking off and cause the slip joint to move and bind.

Any thoughts?

Mod (Ret.)

Have the drive shaft U-joints been checked?

daveborg98

I tried wiggling and twisting the driveline while I was under there and there was absolutely no play in it. Is that a good enough test or does it need to come out to be checked?

Martian

I listened to the sound yesterday and it didn't sound like a U joint. I'd think it would be much faster since the driveshaft spins 3-4 times faster than the wheels. Course I don't know how fast or slow you were going.

Martian

BTW, anyway, along Bucko's lines, a U joint is only $10. You could just replace them anyway and if your problem doesn't go away you didn't lose much, and hey, new U joints