Your noise is definitely a lot louder than mine, but it does appear to be from the same source. But also you have double the mileage 
Help Diagnosing Engine Knock
- Thread starter The Goblin
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- engine knock flex plate
Also, when I changed the oil I didn't see any signs of metal contamination. I cleaned the pan the best I could prior to and I drained the pan through a paint strainer. Some of the stuff like the thin leaf was already in the pan. Results:
brewtus98
TJ Enthusiast
This sounds EXACTLY like my daughter's '03. I also didn't notice the noise during my test drive. Cold start and after the idle comes down the noise starts. Jeep had 140k on it at that time. Dropped the oil pan to check out lower end and NO ISSUES other than a sloppy timing chain. Was going to replace that, but after the results in this thread decided to hold off as that probably won't cure the noise. Also did the motor flush with Seafoam, tried different weights of oil and no changes. Now have 153k on the jeep and still running like a champ, the noise is just irritating. No noise at all when warmed up. Just going to live with it at this point.I'm glad you're looking forward to it, I'm not. Joking aside, I didn't want to buy this Jeep and immediately have to do major engine work. I didn't hear the noise during the test ride.
For now, here's a few video I made previously. The first two were recorded the same day I changed the oil. The last video was a cold start the next morning.
This is shortly after a cold start:
This is from that same start but with the engine at operating temperature. Ignore that I focused on the EVAP solenoid for a second:
This is the next morning, first start of the day. If you notice the noise doesn't start immediately but as the engine oil pressure starts to rise:
Super curious for all of you that have the same knocking noise as mine does as well...do all of our rigs happen to have an automatic tranny? If so what are the possibilities of flex plate OR the torque converter making the racket???
brewtus98
TJ Enthusiast
Mine is an auto and I did check torque converter bolts- they were tight.
5 speed manual here. The same noise has been present in my current manual 2000 TJ, my current auto 99 WJ (albeit quieter), and my former auto 95 XJ.
OP
Nice!! Welcome aboard man! This is one awesome group of Jeep-lovers here who have helped me out a ton. Hopefully we can all figure out together, once and for all, what this darn sound is. There are quite a few 4.0s experiencing the same racket, so if we can help people out, that would be great. Thanks for joining the conversation and thanks for posting your updates!
OP
Hey, sorry I didn't see this earlier. Honestly, the zinc didn't make any difference for me. I tried a bottle of additive, and then I tried using diesel oil with a higher zinc content, no change. I didn't expect much though, because the zinc is more of a protection than a solution. I think if a lifter is stuck, it's stuck; and zinc won't help that. Marvel might. Worth a try.
OP
Mine is auto, and I also checked the torque-converter bolts, nice and tight. I even removed them, put lock-tire on them, reinstalled them, and then spray-painted the tops of the bolts blue to see if they were contacting anything as they rotated (paint would scratch off). All were clear, and now they are a nice shade of royal blue as a bonus!
Still could be a cracked flex plate, there's a guy on YouTube who had a similar sound and his was really cracked. He replaced it and the sound went away. But it's a big job to drop a tranny, and the only way to even check if it's cracked, is to pull the tranny... so, not sure if it's worth it.
But since so many people have this sound, and many are manuals (fly wheel vs flex plate), I'm not thinking that is the issue. It's so weird though, since the sound sure seems like it's coming from right around the bell housing on the transmission! But, as someone else said, sounds radiate!
Not sure if anyone has tried this angle yet? If they have then I apologize. Have you checked the endplay on the crank?Mine is auto, and I also checked the torque-converter bolts, nice and tight. I even removed them, put lock-tire on them, reinstalled them, and then spray-painted the tops of the bolts blue to see if they were contacting anything as they rotated (paint would scratch off). All were clear, and now they are a nice shade of royal blue as a bonus!
Still could be a cracked flex plate, there's a guy on YouTube who had a similar sound and his was really cracked. He replaced it and the sound went away. But it's a big job to drop a tranny, and the only way to even check if it's cracked, is to pull the tranny... so, not sure if it's worth it.
But since so many people have this sound, and many are manuals (fly wheel vs flex plate), I'm not thinking that is the issue. It's so weird though, since the sound sure seems like it's coming from right around the bell housing on the transmission! But, as someone else said, sounds radiate!
Alright Gents, here’s my update with everything I’ve done so far. My “ticking” sound just recently turned into a loud knocking sound so that’s what made me investigate further.
I removed my valve cover to find the rockers and push rods loose on cylinder 3. All the others were tight and had no play. So I played it safe and replaced all of the rockers and push rods. Sealed it back up and still had the same loud knocking sound.
Next I dropped the oil pan
... To find crank shaft bearings 1-6 worn and loose, timing chain loose as hell, and the skirt on piston 2 broken (which is where my loud knocking sound was coming from I’m assuming). So as of now I gotta check to see if cylinder 2 is scored or damaged badly. If it’s not I’ll start putting it back together here over the next couple of weeks.
As of now I’m assuming my ticking sound came from the loose timing chain. However I know that has been replaced by various people on this thread and has still left them with a ticking sound.. with that said I’m still worried about a possible lifter issue... attached are pictures and a video of the timing chain.
Lmk if you have trouble viewing the images.
I removed my valve cover to find the rockers and push rods loose on cylinder 3. All the others were tight and had no play. So I played it safe and replaced all of the rockers and push rods. Sealed it back up and still had the same loud knocking sound.
Next I dropped the oil pan
... To find crank shaft bearings 1-6 worn and loose, timing chain loose as hell, and the skirt on piston 2 broken (which is where my loud knocking sound was coming from I’m assuming). So as of now I gotta check to see if cylinder 2 is scored or damaged badly. If it’s not I’ll start putting it back together here over the next couple of weeks.As of now I’m assuming my ticking sound came from the loose timing chain. However I know that has been replaced by various people on this thread and has still left them with a ticking sound.. with that said I’m still worried about a possible lifter issue... attached are pictures and a video of the timing chain.
Lmk if you have trouble viewing the images.
brewtus98
TJ Enthusiast
My timing chain is just as loose as that. Chose NOT to replace it at this time based on Goblin's results.Alright Gents, here’s my update with everything I’ve done so far. My “ticking” sound just recently turned into a loud knocking sound so that’s what made me investigate further.
I removed my valve cover to find the rockers and push rods loose on cylinder 3. All the others were tight and had no play. So I played it safe and replaced all of the rockers and push rods. Sealed it back up and still had the same loud knocking sound.
Next I dropped the oil pan
As of now I’m assuming my ticking sound came from the loose timing chain. However I know that has been replaced by various people on this thread and has still left them with a ticking sound.. with that said I’m still worried about a possible lifter issue... attached are pictures and a video of the timing chain.
Lmk if you have trouble viewing the images.
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OP
Oh dang!! I'm really sorry to hear that man! Wow, bad bearings AND a broken skirt. Yikes! How did the crankshaft look with the worn bearings? Any scoring?Alright Gents, here’s my update with everything I’ve done so far. My “ticking” sound just recently turned into a loud knocking sound so that’s what made me investigate further.
I removed my valve cover to find the rockers and push rods loose on cylinder 3. All the others were tight and had no play. So I played it safe and replaced all of the rockers and push rods. Sealed it back up and still had the same loud knocking sound.
Next I dropped the oil pan
As of now I’m assuming my ticking sound came from the loose timing chain. However I know that has been replaced by various people on this thread and has still left them with a ticking sound.. with that said I’m still worried about a possible lifter issue... attached are pictures and a video of the timing chain.
Lmk if you have trouble viewing the images.
Good luck!
OP
Someone did say to check the thrust bearings while I had the pan down, but I didn't notice and play at all, front to back, in the crank shaft.
But, I didn't realize that I would need to check it with a pry bar to see if it actually had any play or not, you just can't do it by hand. I think this is definitely something worth checking. Would totally explain why the sound seems to come from the rear of the engine/bell housing of the transmission.
Think it can be checked with the oil pan in place?
OP
Yeah, mine was definitely as loose as this one. And, as you said, didn't fix the noise. But, I definitely learned a lot changing it!
Bbrayden85
TJ Enthusiast
Yea it was definitely a kick in the balls for sure.. haven’t examined the crank shaft closely cylinder 2 didn’t look bad at all from what I could see. At this point though I’m considering pulling the engine sending it to a machine shop and then getting a rebuild kit. My worst fear is that I just fix what Is broken, throw it back together and it’s still ticking... I’m a little hesitant about throwing it back together without checking the lifters after reading everyone’s posts on here haha.
Thoughts?
Not much to update on from my end. The Jeep is street legal so I'm finally putting some miles on it. Right now it has 5 quarts of 10w30 and 1 quart of Marvel Mystery Oil with a Mopar filter. I recently ran a bottle of Valve Medic in there to try and help clean the valvetrain for a hopefully easy fix. This stuff has diesel, kerosene and some other chemicals in it.
So far it really sounds like (insert placebo affect) it's quited the valvetrain while driving. I could really hear some noise upwards around 3k+ RPM and it seems to have quieted that pretty well. It's done absolutely nothing for the cold start knock.
For now I plan on just driving it and doing some oil flushes. The timing chain came in but I'm going to wait to install it at a later time.
On a side note I tried using a rubber hose for a stethoscope to trace the noise location and I really can't find it.
So far it really sounds like (insert placebo affect) it's quited the valvetrain while driving. I could really hear some noise upwards around 3k+ RPM and it seems to have quieted that pretty well. It's done absolutely nothing for the cold start knock.
For now I plan on just driving it and doing some oil flushes. The timing chain came in but I'm going to wait to install it at a later time.
On a side note I tried using a rubber hose for a stethoscope to trace the noise location and I really can't find it.