Unidentified Sound in Engine Compartment - 99 TJ 4.0

[JeepNStein]

Recent 1st time owner since May 2021. 4.0L, 120574 mileage. My 99 Jeep Wrangler TJ 4.0L Sport has been experiencing a ticking sound at start up, idle and driving. During driving or after driving, the sound sometimes goes away. Example is my 20 minute drive into work and upon arrival the sound is gone. The sound is also not always consistent in repetition or frequency. I removed the serpentine belt to determine if the alternator, power steering, idler pulleys, fan pully was the culprit and those appear to not be the cause of the sound. It's difficult to determine exactly where the sound is coming from but lean more towards a lifter and not an exhaust leak. What should my next troubleshooting steps be? AND should I park her until this is resolved. Don't want to do any damage to her. I did switch to Pennzoil 10W-30 full synthetic oil with ProLong Engine Treatment the past two oil changes. I wouldn't think so, but could the change from fossil oil to synthetic oil cause or contribute to the sound? Is there a history of issues with the 4.0L in regards to lifters or whatever this might be? I am also attaching a video from startup this morning. Thanks in advance for suggesting next steps.

View attachment 443443

 

[ColoJeep]

That's a tough one to determine with video , there is a little actual lifter noise to the backround , but the primary click with a little chirp is hard to determine.
Get a real long screwdriver , bunch of socket extensions , etc. about 3 - 4 feet long and touch around the distributor with your ear at the opposite end to track down the noise location. BE CAREFUL ! watch the fan and bare electrical connections . Good luck with the hunt!

 

[JeepNStein]

Thanks for the tip. I fired her up shortly after your message and the noise was no longer there. However, this morning it was back until I revved the engine up a bit. I used a stethoscope to probe around the distributor and valve cover area. Cylinder number 5 is a little louder than the others so perhaps that is the culprit. In reading some other threads and watching youtube search results, I am thinking that it can't hurt to pull the valve cover off and inspect the rocker arms, pivots and pushrods. It's an inexpensive and easy fix if there is wear that requires replacing those parts. Not sure where else to look at this time so I am resigned to continue driving it. Any other thoughts/suggestions are welcome. Thanks.

 

[ColoJeep]

Thanks for the tip. I fired her up shortly after your message and the noise was no longer there. However, this morning it was back until I revved the engine up a bit. I used a stethoscope to probe around the distributor and valve cover area. Cylinder number 5 is a little louder than the others so perhaps that is the culprit. In reading some other threads and watching youtube search results, I am thinking that it can't hurt to pull the valve cover off and inspect the rocker arms, pivots and pushrods. It's an inexpensive and easy fix if there is wear that requires replacing those parts. Not sure where else to look at this time so I am resigned to continue driving it. Any other thoughts/suggestions are welcome. Thanks.

Try this the next time it happens on start up , after it starting clicking shut the engine off wait 15 - 20 seconds and restart If it's a lifter it will usually be quiet.
This method has worked on my wife's 04 4.0 when it occasionally clicks. No issues . Note: You may have to put your foot on the throttle to get the engine started and running , This is because you confused the computer with the cold shut down. Give it a try and good luck !

 

[JeepNStein]

I tried your (ColoJeep) suggestion and it did not go quiet. I did an oil change yesterday and the sound is now LOUDER than it was before the oil change. I am going to do another oil change but this time with Dino oil instead of the synthetic... along with some Marvel Mystery Oil to see if that makes a difference.. If the noise is still there then I feel fairly confident that it is a hydraulic lifter. The lifters are inexpensive and it does not seem to be a difficult job to do... (Watched a YT video). However, not a lot of free time and never have done one before..... Any idea on how much a mechanic charge? And is there anything else to look at while she is open?

 

[ColoJeep]

I tried your (ColoJeep) suggestion and it did not go quiet. I did an oil change yesterday and the sound is now LOUDER than it was before the oil change. I am going to do another oil change but this time with Dino oil instead of the synthetic... along with some Marvel Mystery Oil to see if that makes a difference.. If the noise is still there then I feel fairly confident that it is a hydraulic lifter. The lifters are inexpensive and it does not seem to be a difficult job to do... (Watched a YT video). However, not a lot of free time and never have done one before..... Any idea on how much a mechanic charge? And is there anything else to look at while she is open?

Take a look at your exhaust manifold , ( cracked/leaking ) and the wires around the rear of the cylinder head for chaffing on the stud on the corner of the head. Be carefully pulling the head off , it's a heavy son of a gun ! Make a copy of the service manual on paper to refer to as you work. Take your time and enjoy something mechanical to your Jeep !
If you don't want to be too involved , find a mechanic who is a Jeep guy and get a quote. good luck on your quest.

 

[hear]

Are you sure it's not the distributor itself? The bearing went on my 97...can't remember what it sounded like but once I put my finger on the cap it was evident where the noise was coming from.

 

[JeepNStein]

Are you sure it's not the distributor itself? The bearing went on my 97...can't remember what it sounded like but once I put my finger on the cap it was evident where the noise was coming from.

Thank you. I will explore that as welI. I did stethoscope it early on but now that the sound is louder perhaps that will help in the diagnoses. That would be much easier to replace than pulling the valve cover to check the rocker arms or removing the head to check the lifters.

 

[JeepNStein]

The Continuing Saga of the Unexplained Noise. I earlier posted that I switched back to dino oil and a quart of marvel mystery oil on Sunday. Sound was there Sunday and Monday. Yesterday (Tuesday), I started her up and started to stethoscope the valve cover, the distributor and the head as I was able to. About one minute in, the sound went silent. WTH? I let her run for 5 minutes.... Sound of Silence continued. Revved her up a bit and the sound came back momentarily and then went away. Shut her off. Waited 30 minutes. Started her up. Let her run for 5 minutes. Silence. Repeated a few times. I then took her for a spin around the neighborhood. Silence. Engine ran smoothly. I am perplexed about this. Not sure what else to do at this time but just drive her and monitor any engine noises that might appear later. I suspect that one of the hydraulic lifters was the issue but I don't want to invest time right now to tear it apart to investigate. Any suggestions? Is this something that is normal with the old 4.0L? I do like the Sound of Silence and may just started blaring the Disturbed version of that song while driving her around. Start of a new superstition.

 

[JeepNStein]

That's a tough one to determine with video , there is a little actual lifter noise to the backround , but the primary click with a little chirp is hard to determine.
Get a real long screwdriver , bunch of socket extensions , etc. about 3 - 4 feet long and touch around the distributor with your ear at the opposite end to track down the noise location. BE CAREFUL ! watch the fan and bare electrical connections . Good luck with the hunt!

Alrighty folks. FINALLY figured out where the annoying chirping sound was located as it has gotten progressively worse of late which allowed me to pinpoint the precise location... and the winning troubleshooting suggestion came from @ColoJeep. I used the stethoscope to check the distributor and bingo. Removed the cap and the rotor. Both in good shape. Was able to twist the distributor slightly. Reinstalled the rotor and cap and started her up. Grabbed the distributor and applied a little pressure and bingo.... the sound stopped. Released it and the sound came back. Sooo... now I will be ordering a new distributor... Any suggestions on which ones to avoid and which ones to buy? I am willing to spend more for quality.

 

[ColoJeep]

Alrighty folks. FINALLY figured out where the annoying chirping sound was located as it has gotten progressively worse of late which allowed me to pinpoint the precise location... and the winning troubleshooting suggestion came from @ColoJeep. I used the stethoscope to check the distributor and bingo. Removed the cap and the rotor. Both in good shape. Was able to twist the distributor slightly. Reinstalled the rotor and cap and started her up. Grabbed the distributor and applied a little pressure and bingo.... the sound stopped. Released it and the sound came back. Sooo... now I will be ordering a new distributor... Any suggestions on which ones to avoid and which ones to buy? I am willing to spend more for quality.

Glad you found the issue !!!!

 

[JeepNStein]

Quick update. The replacement of the distributor was so easy that a caveman can do it! Just a couple things to be aware of. I set my rotor pointing to the Noon position. I placed a piece of masking tape on the engine and used a Sharpie to mark the rotor position on the tape. This made it easier to align up the new distributor IMO. When I went to install the new distributor, the rotor was pointing a little to the right of the mark... or so I thought. After comparing the rotors, the new rotor (metal piece that contacts with the cap locations) was SHORTER (less wide).. Phew.. I thought I had done something wrong but nope. It started up and is running like a champ. One thing that I was experiencing previously were hard starts. Mechanic said it was the battery. (I called BS immediately). I believe it was the distributor. Starts upon 1st try instead of 2 or 3 attempts. Idles immediately instead of having a few seconds of rough idle. All in all it was a good lesson learned about distributors and the symptoms on 4.0L TJ's.