I know theres a million threads on it but couldnt find exaclty what i was looking for. I bought a 2011 fx4 with 111k miles. Truck runs good but has the slight knock. Its not there everytime and sometimes it does it cold or hot.....ive searched and read its either something with the ac belt. Timing chain tensioner and water pump. Or the block....is there any pics or info on the ac knock. Mine seems to not do it when i have the ac on. Could be coincedence. But figured if start with the easiest first.

 

It may also be the exhaust manifold or exhaust gasket.

 

It's probably had the noise since day 1 like lots of 5.0's seem to have. If it was an issue I feel like it would have made itself more apparent by now. As long as it isn't a super loud obvious rod knock, if I were you I wouldn't worry

 

It may be. But i dont think so. Ill check over every bolt on them to make sure. But i had the 5.4 and had the manifold leak like all them lol. But you could hear the leak only at cold startup and WOT. This truck sounds good all the time

 

I would say youre right. Truck does great aside from the noise. Its just one of those things. I cant stand having a noise like that though. Last few fords ive had had cam phaser and timing chain trouble.....plus my dads a big chevy guy and gives me hell anytime i gotta work on them lol

 

Just curious, does it have a CAI on it or high flow filter? I was experiencing this on my truck and I also had a catch can. I have about 45K on mine. I removed all the mods under the hood and it seems I can't hear the knock anymore, so maybe the CAI on mine was amplifying it, not sure but I am still watching it and listening real close.

 

No cold air intake...just a weld in borla. i did take the silencer or what they called gotts mod on the 5.4s. But i didnt like how it sounded. So put it back on

 

Use a stethoscope and check the rear lower part of the block for thrust bearing clearance.

 

At that point in the trucks life having 111K and making noises. In sure it's all good.. My 2011 is at 83K and makes all sorts of noises on different days haha. Just drive it and enjoy it !

 

A guy told me once a good engine shouldnt make any wierd noises....these days 100k miles isnt all that much. My brother had a suburban with 300k and it was quiet. My dads gmc has 125k and its quiet. Ill keep driving and enjoying it. But also looking for the problem thats causing the noise and fix it.