To start off I am a Heavy Line GM tech ASE certified and all, that's right and I own fords...

3 weeks ago I picked up a 2004 F150 Super Crew Fx4 it had phaser noise but had zero rust and 120k
I tore the front of the engine off and found loose chains, collapsed tensioners and the locking pins in the phasers were worn. I bought the livernois motorsports can phaser lockout kit and installed it with new ford chains, guides and tensioners. After that the engine sounded great! Like a new truck! Then yesterday I was driving and started hearing a faint knock with no loss in performance. Today I pulled the coils off and checked the spark plugs and found one hand tight (not my doing) spun it out by hand, I managed to set a world record and have all plugs out without breaking any. I got pretty excited about finding the loose plug and rushed out and bought 8 new moforcraft sp515 plugs threw them in then changed the oil (for good measure about 150 miles since previous repair with Mobil 1 5w20 and Motorcraft Filter) and cranked it over....No Change...

So here is the best way I Can accurately describe the noise, Deep and Hollow Thump, Seems To be loudest under the oil pan sump/bell housing but can be heard In cab, In the wheel wells and slightly from under the hood, It increases In volume with rpm/load at Idle and Highway speeds 65-70 1500-2000rpm it is almost not noticeable. In park, Rpm around 1200 to 1700, It is loudest

I have poked around with my stethoscope and a length of hose and can not pin point the orgin. I can say with certain it is not the phasers (locked) and It is not the exhaust manifolds/gaskets/broken studs. It does not sound like a rod or main bearing knock to me.

Does anyone have any ideas? If not Im going to pop the valve covers and check the lash adjusters and followers tomorrow even though I doubt they are bad they looked like new last time I saw them.

Any Input helps!

 

wonder if you are getting oil up to the camshafts? wonder if the flexplate is broken?

 

Well it wasn't loud enough for me to think about it being a main bearing or rod bearing, but it is, I cut open my filter and found a evidence of a surprise visit by the glitter fairy! I dropped the pan and the rear most main bearing is smoked, on a side note does inyone know of any differences from 04-05 3v blocks?

 

ouch............

 

My truck started doing the same exact thing for the first time last night, I thought it was maybe a loose heat shield on the cats. Looks like I will be taking the truck in to get looked at.