Very bad rattle noise in top of a 4.0 overhead cam .gas engine but sounds like a diesel !

unless you have a distinct chain rattle noise then it will last longer than a belt which is 100,000klm so have it checked but it should be good for around 120k

if it is a turbo diesel (TDI) I suspect that the injectors need attention
if they are squirting , dribbling or are not atomizing as required then the diesel may be igniting before ignition time causing piston slap (the rattle)
Take it to a diesel specialist shop for a diagnosis and quote

It could be several things causing the rattling such as: low octane gas, timing off, or a bad bearing in the lower half of the motor. I'd start with changing my gas to a premium grade and go from there.

This can be a sound made by "cam phaser" engines that Ford made for 4 or 5 years. Usually the noise quits above 2000 rpm as the phasers limit out in their travel. These engines are very sensitive to the correct weight oil being used and a Ford filter being installed.

The noise has been described as a muffled diesel rattle. Owners report stalling, hesitation, poor acceleration, but most do experience vibrations. What is happening is each bank of cylinders is suppose to be synchronized by the phasers. Imagine if half of the valves are firing several degrees earlier or later than the other half of the engine. Since these adjustments constantly change it makes trouble shooting difficult.

Other areas for rattles are the beads in the catalytic converters which may loosen and float inside the converter or even loose baffles in honeycomb design converters.

I have had terrible noises coming from gravel and rocks trapped in between the heat shields of catalytic converters especially if you travel gravel roads. Since you have "knock sensors" you can get driveability problems from the engine trying to misinterpete the knocks and rattles caused by rocks.

Buy a chiltons manual that's specific the the cyl heads your trying to remove. I'm guessing your talking about heads on a car ? By not including a make, model, year , engine size , diesel or gas, overhead cam, naturally aspirated, turbo, fuel injected, carbureted there is no way to answer the question you are asking. Your biggest concern should be on how to reinstall them. Reinstalling heads are far more complex than removing them. All heads are different in the pattern in which they are tightened down ( to prevent warping ) . A specific amount of torque must be applied to each bolt. Some bolts require thread sealant because they pass through the water/coolant passages in the engine. Failure to do that will result in water leaking into you combustion chamber thus ruining your engine as well as your new head. Also the thickness of the head gasket must be correct because to thin or to thick of a gasket will change your engines compression ratio . The gasket thickness can also change your cc's in the combustion chamber. A gasket that's to thin can also allow the exhaust or intake valve to hit the top of the piston on the compression stroke. If your dealing with an overhead cam or dual overhead cam engine then the proper setting of the camshafts when reinstalling the head or heads is crucial . The above only pertained to gas engines. If you have a Diesel engine then things change dramatically . The pressures in the cylinder head combustion chamber area on a Diesel engine is unbelievable . One small mistake or oversight on reinstalling a head on a Diesel engine can be catastrophic .

that would be the engine front , you sure it's a Rattle ? if so ? it will be your Camshaft bearing noise, is it a 2.5 L 4 cylinders ?or 3.5 L V 6 !! .
if it's 2.5 L , your Camshaft bearings are starving for oil , so I suggest you check them both intake and exhaust cams and see also if the valve lifters or cam bearings are in bad shape , worn out ? check also both cams journals and drive journals to lifters ( contact operation ) if there is a suspicious gaps between them that also can cause a rattle sound .

Knocking noises from the overhead cam may be making the noise in question. Maybe a bad bearing on the camshaft or a spun cam.

175,000 mi. is a lot of miles for an engine, it may have been over revved at some point, or suffered from oil starvation or dirty oil with a prior owner.

a rod bearing makes noise when you are just barely pulling .. it likely will quiet down as you accelerate and decellerate .. you can rev the engine up a bit then let up on the gas just enough to keep that rpm ..a rod bearing will rattle a lot then ... if a thud like noise happens when you are accelerating . then it could be a main bearing .. if the noise is there all the time and sounds like a rattle then its more likely a valve problem .. old oil can cause the lifters to stick and rattle continuously .. if the noise you hear is a squeal then you could have a bad bearing in the idler pully (for fan belt) or alternator .. if thats the case you can put a drop of oil on the bearings one at a time until the squeal goes away .. that will identify which part is going bad .. there are other less likely bearings that can go bad .. like the cam, distributer, air compressor and water pump .. each have their own type noise ..

There are no Lifters in the Dual Overhead Cam Motors. Once these 2.4 Liters start Tapping, It is just a Matter of time Before they Stop. I had to Replace one not very long ago for a Customer with the Same Problem. Please Rate my Solution, I need all the Help that I can Get! Thanks!

This recall only applies to the double overhead cam 4.0 liter V6, if that is what u have then this may be the rattle, they can get pretty loud, call the dealer or call Ford direct, u will need the VIN number of your truck, with that they can look up this info and see if u need the recall, if you u do qualify it will be done free of charge unless you are out of time limit, which may or may not apply, even if u don't need the recall I would replace the cam chain tensioner's anyway.