Tambourine noise under the hood

I’ve got a 2002 ford F350 diesel truck. When the weather gets warm it sounds like there’s a tambourine under the hood. My husband has looked under the hood but since neither of us know anything about cars or trucks he didn’t see anything. When it’s cool or cold it doesn’t make the noise. When the air conditioner is off it’s not as loud either.

Without being able to hear it myself and look around, the best I’d do on that description is to say that it has something to do with the accessory drive (serpentine) belt & its pulleys. If he is really really careful, he can start up the truck, take a piece of hose, stick one end in the ear and fish the other end around near all of those pulleys where the belt runs). It helps to pinpoint those sounds that seem to come from everywhere & nowhere. The reason to be really careful is, of course, that those things & the belt are spinning around very fast.

It is also possible - if anyone is feeling up to it - to pull that belt and run the engine briefly (not too long as there will be nothing to run the alternator). If the noise goes away then you can be pretty certain about a noisy pulley.

Of course, if neither of you know very much about cars you might want to just get it to the mechanic. It shouldn’t be hard for someone to figure out.

Thanks, Is it a real serious problem possibly? I was hoping to wait to go see the Ford dealer at our home location instead of a stranger here in TX. in a few weeks. We do pull a 34 ft. fifth wheel with it from TX to Neb.

Best guess since the noise is less with the ac off ac compressor would be suspect 1, early intervention would be advised. Hopefully you can find a local guy who can do the necessary repairs, worst case scenario something seizes, breaks belt ford (found on road dead)

I’d have to agree with waterboy on early intervention, just in case. The last thing you want is to be F.O.R.D. somewhere on the way back to Neb. This doesn’t mean that it really needs to be repaired right away, but you’d want to have an experienced mechanic listen to the noise and inspect all of the pulleys - if that even is the problem. Heck, you might just have a loose heat shield or something in which case there’s no need to worry unless its about to fall off and damage something else. Unfortunately, if it does turn out to be the AC compressor, that isn’t a cheap repair. The others would likely be less so.

The first thing I’d do is try a bit harder to find the source of the noise and report back if you get something somewhat definitive. And start asking around wherever you are for a local, trustworthy shop - ask enough people and hopefully you’ll start hearing the same name/s popping up.

thanks, we have an extended warranty so I can go to the local Ford dealer.

Is this noise present at idle only, all speeds, or only when the engine is under a load (passing, uphill, etc)?

If the latter then you should suspect an EGR system fault.

when it’s there it’s there all the time. Now today it wasn’t there at all but a couple days it was all the time I was driving it. It seems to be there when the outside temps are warmer to hot.