Popping or tapping sound

[Firemanray]

My started making some intermittent noise like that, as it progressed it became apparent that it was the fly wheel. It finally broke the entire center out of it.
Make a note whether it's only happening in gear or if it does it in park as well.

[packmule1911]

It's happening while in park and in gear.

I was burping the cooling system last week, and I think it's coming from the radiator. Definitely from the very front of the vehicle. Maybe one of the mounting points is loose, or there's a pressurization/release event going on that causes something to move and bump into something else, creating the knock I hear.

I sometimes get a slight coolant smell inside the cab, so I'm keeping an eye on that whole system.

[Jovan1982]

Sounds like a problem I had before. Lay down underneath the rear end and take a close look at the leaf springs. Check to see if the crimps have come loose. They make that inconsistent sound you are describing. Its worth a look?

[packmule1911]

I'll get under there and take a look. It sounds very much like it's the front end, engine bay, near the radiator. I know that the unibody transfers sound in odd ways, so maybe it is the rear. It does this at rest though.

It still seems like something under pressure, or torqued, that releases. Like a bubble in the radiator, or something not entirely tight that moves when it heats up.

Nothing seems wrong per se, it's just annoying, and I like to know the cause of all the sounds this things makes so I can disregard non-issues and reduce my fretting.