Popping or tapping sound

[packmule1911]

Lately there is an inconsistent audible "pop" or "tap" sound coming from the front of the car. The tap sound like someone lightly tapping with a small hammer. It could sound like a pop as well, kind of the pressure valve releasing, or something under tension releasing. It's not loud exactly, but it's annoying and I hate having a sound within ear shot whose cause isn't known.

Sometimes it will do it at idle and be like pop (2 seconds) pop (2 seconds) pop (2 seconds). Other times there might be more or less space between pops and/or a different number of them. It's not consistent in how many sounds happen, the tempo, etc. The sound is always the same pitch, volume, and duration. Of course it doesn't do this when I'm trying to listen under the hood. I expect it might be making them when driving too but there's a lot to drown them out then.

The only things done around the front end are:

* front sway bar bushings
* front sway bar link rebuild kits
* removal, cleaning, and reinstallation of the IAC
* oil change
* rebuilt front axle 12/9 but the sound was there before that
* new front wheel bearing/hub assemblies
* front brake caliper pins removed, cleans, greased and re-installed

None of this stuff seems like it would cause an intermittent pop or tap sound from the front.

This is driving me nuts. Thanks for any suggestions you can give.

[nickyg]

Does it make the noise when you are turning the steering wheel?

[packmule1911]

Nope. Dead stop at traffic lights or in the driveway.

I did also lube the chassis: tie rod ends, ball joints. I did lube the sway bar bushings with vegetable oil, but I did not use any lube on the sway bar link bolt sleeves or bushings. I thought for a minute that maybe the suspension is getting "wound up" and the pop is dry rubber releasing itself. I don't know anything much at all about Jeep's yet, so that's probably an ignorant idea.

[4.3LXJ]

That sounds like one that will require you to get out and try to find exactly where it is coming from first

[packmule1911]

Trying to do that. Spent a good while listening today. Don't really want to hop out a stop lights, but that's when I hear the most consistently.

[nickyg]

Mine made aloud pop at random when turning it wound up being the trackbar mount on the frame had bolts rusted to a nub.
whenever I drive over something hard my swaybar links hits the spring. but that makes a sorta bell ringing sound.
..... I'm stumped... but that's not hard to do.

[autotech98]

My heat sheild on my cat is loose and makes a poping or tapping sound

[denverd1]

stopped while in gear. reverse the same?

[packmule1911]

Still going on. Getting more frequent, but no consistency. When whatever it is fails entirely, I will know what it was.

[WhiteDevil1311]

In gear and in park/neutral? Do you have a mechanics stethoscope?(long standard screwdriver...handle to ear if you dont want to buy or have the proper tool). Have you pulled and checked your plugs?

[packmule1911]

Plugs are brand new. Did it before plugs as well. Car is in gear, but usually, but not always, stationary. The sound could be considered by some to be a knock sound.

I need to grab a drink and a stool and let it idl for an hour while I sit watching and waiting.

[WhiteDevil1311]

Could be a lifter going out? Any findings?

[denverd1]

those are jeep noises. Mine makes a lot of them. wife always, " what's that noise???" It's the jeep, honey. Just doing its thing.

If you think it's engine related, you can use a long screwdriver as a stethoscope to nail down what cylinder its coming from.

[WhiteDevil1311]

I thought that too denverd1. Bit when i did a full tune up the noises ceased and have stayed gone. I dont understand why or how except bad plugs. Mine now has 177k on it nd is quiter then the neighbors brand new zj

[98FloridaXJ]

Have you checked your control arm bushings? Mine was making a similar pop that went away when I replaced my upper control arms.

[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.