2005 f150 5.4l problems

I have a Ford f150 5.4l 2005. I just did a motor swap with a motor that has 26000 miles on it. When the motor is cold it runs and sounds great. As it warms up there is a pulsating sound like a ufo (only way to explain). I changes out tensioner and put new serpentine belt. Could this possibly be my bearing going out on my alternator pulley? Please help I'm done sinking money into this thing!

sounds are one of the worst things to figure out. And I'm not sure how a UFO would sound. I usually go for a ride with the customer or have then demonstrate the noise in the parking lot. Otherwise I might fix a noise that the customer didn't want fixed. (and that's happened before)

so I take it that the noise is coming from the front of the engine. is that correct? does it sound like it's coming from the belt area? Is it happening while the engine is idling? If is does, you could run the engine until the noise is present. Then turn the engine off and take the belt off. Spin all the pulleys to see if any feel rough (that may cause a noise) then start the engine with the belt off. is the noise still there or is it gone. DO NOT RUN THE ENGINE FOR VERY LONG WITH THE BELT OFF. WATER PUMP WON'T BE CIRCULATING COOLANT! Then put the belt back on and start it up and see if the noise is back (if it went away with the belt off that is)

that may help you to narrow it down a little. OR, is the noise from the IAC?

It sounds like its at the front of the motor, but it echoes throughout the engine compartment it is hard to pin point. That was my next idea was to take the belt off because once it heats up is when the sound starts. One thing I was told by the mechanic who put the new motor is the flywheel only had two bolts in it when there should be four. He thinks the torque converter was damaged and wobbeling around making the sound. Thank you so much for the input. This has been the most knowledgeable opinion yet.

ok, that is very strange. I have not known of a converter that bolts up to the flexplate with only two bolts. If the mechanic removed the original motor, how many bolts or nuts did he take off the old motor? Should be the same as the new one...

Okay new developement. We took the plug our on the bell housing where the torque converter is located and the sound was very prominent. We finally dropped the transmission and removed the torque converter. The problem we are running into is pinpointing which part is damaged and making that sound. It could be the torque converter. To the crankshaft or anything. We did notice that the end of the torque converter that fits into the motor had a beveled part that looked like metal was shaved off. Our best guess is it has loosened that TQ up and it's moving around. I still can't seem to find anyone who has heard that noise. That is my luck ha.

take a picture of the part that looks like it was damaged and also the part of the motor where it looks like it mated to and take it to a tranny shop and ask them if they can tell you what the problem looks like to them.

Sounds good I'll see what I can do thanks!!