5 months ago I did the Plenum repair with the hughes engine kit. About 3.5 months after the repair this strange poping noise started. The noise has no pattern and just pops randomly. Sitting still, accelerating etc...

I cant for the life of me identify where its coming from. I thought it sounded like it was coming from under the thermostat housing so i changed the thermostat out and still makes the noise. Best i can describe the noise is if you took a wrench and tapped the top of a valve cover. That's what it sounds like. Thought maybe plenum plate popping or something strange, but that plate is so thick I couldn't see it doing that. Intake manifold is still clean.

Truck has new timing double roller timing chain, water pump, IAC replaced 1yr ago, new oil pan gasket, plenum repair. Everything torqued to spec.
Any ideas. Gonna try and get a video of the sound and upload it tomorrow.

 

Do a compression test. See what your numbers look like. I suspect you have a valve that isn't completely closing on occasion.... or a cracked valve seat.....

Ran any seafoam thru the intake?

 

Sounds like a misfire or wires arching. Does the sound increase while accelerating?

 

https://www.youtube.com/watch?v=5Ti7...ature=youtu.be



First time happens at 2:09 Second time 3:12


Its not a rough running engine popping noise. This happens at random don't know when it will make the noise. It just happens when it happens. Just clueless as to what is causing the noise. Any ideas? Thanks

 

Sounded like the AC clutch engaging or disengaging.

 

Not the a/c compressor. Its off, and I unplugged it just to be double sure.

 

almost sounds like the thermostat poppin open or closed to me. if u have a piece of pipe use it to amplify the sound, stick it down by the t-stat housing and put ur ear on the end, wait and see if it louder or not. engine sounds fine till this "pop" and its a min apart almost exact, just sounds like the t-stat opening or closing and might be a little worn out or stuck so it pops.

 

I'd pull the belt off and run it for 15-30 secs next time I hear . I don't think it's "engine" related , more like a bearing noise on one of the bolt on's . Could be AC , Alt , PS or a pulley bearing IMO .

 

bearings wont make a single pop sound. they would have a constant sound, starting faint and growing more the worse it got.

 

I took the belt off for the heck of it just to try it. Also quieter so i could listen better.
I went around the entire engine and re-torqued every bolt. Couple of the intake manifold bolts were only at 5-7ft lbs some reason so i turned them back to 12ft lbs. Everything looks fine. Nothing else loose.

I have determined the noise is coming directly from under the intake manifold. T-stat was changed. Could the plenum plate be making the noise somehow? I torqued the bolts to spec with blue loctite when I did it. The noise didn't start until about 3 1/2 months after the repair. It doesn't seem to affect anything, its just annoying.