Whenever I'm gently accelerating from a stop I get a loud ticking from the engine bay (sounds like driver's side) that will go away once I get above 1000 rpm. Even though it goes away fairly quickly, and then doesn't come back till I'm below 1000 rpm, it is still beginning to concern me. The car also has to be in gear for the noise to happen, there is no ticking whatsoever at idle. It's not the A/C. Would an exhaust leak be a good bet as to what this noise is, or could it be something going on beneath the valve covers?

 

Does it go away when you put the clutch in?

 

Sorry, forgot to mention that I have an auto.

 

oh, because my car makes a ticking sound too, and when I push the clutch in it goes away...I think it might be my harmonic balancer, its pretty janky...I definetly need new pulleys

 

i have it too...i think its the shims?

 

That's probably because the motor RPM's drop slightly when you are in gear as the torque convertor loads up.
I'm wondering if it's a cam follower draining oil as the pressure drops due to low RPM. Sometimes a single follower might have a slightly larger drain hole than the others, a fluke of manufacturing, and that can be more susceptible to low pressure drain especially if the oil is getting thinner.
Any motor ticking/clunking/knocking is always something you want to investigate earlier rather than later.
Does it make the noise when the motor is cold ?
As a first step I would change the oil & filter to ensure the oil pressure isn't being stiffled by a bad filter or gunky oil.

 

It will do this at any temperature.

 

My car had a pretty bad header exhaust leak and it could be heard at high rpm cold start idle but not regular idle at like 700rpm. and was loudest at low rpm high throttle setting. I could hear it all the way up to about 3500 rpm though. And it sounded like a rapid ticking sound coming from
the driver side. My car is a manual btw

 

Just curious to see if you ever got this resolved? My 2010 does the exact same thing. Wont do it if it's not in gear, only under load, and only between 900 and 1300 rpm. Took it in to the dealer and they told me it was normal noise. I use mobil1 5w20 in it, and he saidthere is a tsb out on this noise and it says it can be worse if you get away from motorcraft.? I have'nt been able to locate the tsb.

 

It still does it, but I've accepted it as normal after meeting a few more Mustang owners that have the same issue. What you're describing sounds like the exact same thing, and if the dealer says it's normal then I guess there's nothing to worry about.