2001 Ram 1500 5.2 engine:the last two mornings on cold (65 degrees) start there is a random and metallic sound like a loud click at idle every 10 seconds or so coming from general area of engine front. Like a noisy a/c clutch kicking in but no a/c operating.
Disappears when driving and once driven disappears for the day!
Thinking maybe coming from timing chain area?
Is that possible?

 

Exhaust heating up? Water pump bearing? How many miles? 65 isn't cold enough to hurt anything. How's the oil? What's the life of the truck been? Need more info.

 

Have you looked to see if it is indeed the compressor engaging? It will come on in the defrost mode also not just AC.

 

My 2004 4x4 quadcab, with 4.7 magnum makes that noise, but have traced it to the bell housing, it is really loud when cold, 60 and lower, after warm up it is gone, almost has the sound of a loose heat shield but metal on metal, like a loose bolt hitting something.
I run pure synth oil in engine and trans, and transfer, I have 124K miles, started around 115K and comes from Right side of Bell Housing.
When it 1st started it was intermittent like 2RamsJake, but has become more like a rod hitting the wall....(Speeds up and slows down with engine)
No loss of power, no other driveability issues....
Dewy

 

Thanks.
Mystery.

 

Flywheel....
Appears the teeth are coming loose....
So off to get another, good thing there are about 50 near by.....