98 1500, 5.9 gas, with 180,000, well maintained but have a single pop sound randomly, when idling and while driving. It does a single pop every few minutes or sometimes several times in a minute. No engine light. I used a stethoscope and it’s coming from the exhaust manifold at the engine. No noise detected on the oil pan, intake, or valve cover using a stethoscope. It is not the AC kicking on. Seems to be getting more frequent lately. It is NOT the manifold heating and cooling that is making the sound. I replaced plugs with stock copper champions, new rotor, cap, wires, didn’t make a difference. I ran a full tank of premium 93 octane, no difference, tried non-ethanol as well. It is a fairly loud single pop that I can still hear when idling or accelerating moderately. Engine all stock, Doesn't matter if the motor is cold or hot, still does it. Any ideas would be appreciated.

 

Wow. That's bizarre. Could you upload a longer movie?? Give some sense of what is going on??

 

I tried to upload a longer video, but it said 5MB limit, so I had to edit it down. Sounds like a metallic pop.
I can try to take a longer video and upload to YouTube when I get a chance

 

Yeah, I think youtube is a bit more liberal on video size.

 

here is I slightly longer video, Pops 3 times during this video. Make sure your volume is up. Not a You tuber so excuse the camera work

 

Is it an exhaust or mechanical noise? I would get inspection mirror and look around(under) the manifold. Might take the valve cover off to see if anything in there is wonky.

 

It sounds like a mechanical noise coming from the exhaust manifold I think there is an issue with a valve, but not sure. I do have a new set of heads I could put on, but don’t want to replace them and that not be the issue. As suggested I can pull the valve cover and watch the valve train to see if any obvious issue there

 

Running it with the valve covers off is messy.

It sounds like a heavy solenoid engaging...... but, it's not the a/c clutch??? The engine doesn't seem to miss when it happens, so, I doubt it's a valve train issue.

 

It is definitely not the AC, pin pointed it to the manifold using a mechanics stethoscope, can’t hear the pop anywhere else on the motor. And you are correct, no miss fire or stumble when the pop happens.

 

Can you localize it to a specific cylinder??