Jeep Wrangler TJ Engine/Flexplate noise while revving engine

[@garridak]

Keep us updated! Currently having the same sound and trying to find the problem. Tightened TC bolts didn't fix it either. Hoping for some miracle to happen with an engine cleaner rather than cracked flexplate or piston skirt

[@ProVisionColor]

Nothing yet, sorry. Sounds like there are a BUNCH of people having the same issue. There's a really great thread going on over on wranglertjforum.com where I chronicle all my steps and there are a bunch of other folks adding to it too. It's turned into a really robust reference manual! Lol. Just search for thread by TheGoblin (that's me), and you will find it. One guy just joined the conversation and sadly when he dropped the oil pan, it was full of broken piston skirt pieces. Mine was totally fine though. I will keep you all posted if/when I find anything. Good luck with yours!

[@davejames2015]

Did you figure it out?​@ProVisionColor

[@ClanOxyL]

Well it looks like a lot of people are having this noise from their jeep with no solution judging from the comments. I just bought mine and this is what my noise sounds like and from the same area . Runs great otherwise and I can't hear it when I'm driving . (But my exhaust is loud and leaking right now.) My jeep is a manual transmission btw. I just got it so I haven't pulled the pan yet . I was thinking maybe thats just how this old jeep engine sounds but I like to think I have a good ear for a smooth engine and it just sounds but I put my ear on the oil pan and it definitely sounds like something is kind of tapping or clanging . But I still need to get a screwdriver or stethoscope on it to pinpoint it a bit better. You seem like you're still actively dealing with this, I will keep in touch.

[@ProVisionColor]

Seriously! There are a TON of people with this same sound! And so far, no uniform answer. It really feels like it's just something with this straight 6 4.0L engine. It just rattles! Lots of people weighing in on this topic over on wranglertjforum.com. You're welcome to join the conversation there. Just search for threads by The Goblin (that's me), and you will find it. Lots of good info there. Good luck with yours!

[@moeshiner156]

I have run into broken fins inside the torque converter but that sure sounds like wristpins to me.

[@bdc7273]

Lol my brand new magnum 360 makes an almost identical noise😑 completely different engine I know. Noise is very similar. On a brand spanking new motor...

[@ProVisionColor]

Hey everyone. My Jeep is still as noisy as day one, but it's going strong. One guy over on WranglerTJforum just posted an update on my thread and he solved his rattle. Thought you all might want to check it out. Here's the link to the forum thread. Just go to page 14 or so and you will see his work. He replaced his pistons and wrist pins. wranglertjforum.com/threads/help-diagnosing-engine-knock.33602/

[@timothywolfe-ol8uk]

4.7 magnum making similar noise. Dropped inspection plate tonight and found cracked flywheel. With the inspection plate off it was loud and very clear that was where the noise was coming. from

[@ProVisionColor]

Ah! Cracked fly wheel huh? Glad you found the problem! I'm not ruling out a cracked torque converter on mine (it's an automatic), but I can't see any cracks at all on the front side of the disc. I would have to pull the entire transmission to inspect it, and I'm not sure I want to do that. I'm leaning more towards piston slap for mine, or maybe a stuck lifter.

[@keenanp9045]

I have the same noise, but I tightened all my flex plate bolts. I don’t know what it could be

[@ProVisionColor]

Welcome to the club! Lol. So far, none of us have been able to figure it out. Good luck with yours!

[@Crondo420ReFrEsHe]

Itsvthe torque converter bolts. You have to take the flexplate off and tighten them.

[@ProVisionColor]

Unfortunately not the TC bolts. Removed them and re-tightened them multiple times. Wish it was that easy though!

[@robertbrown7393]

Join the crowd, I’ve got same noice. Did you ever figure it out.

[@ProVisionColor]

Not yet. Sounds like there are a ton of us who have this dang sound, lol. Good luck with yours.

[@kevint1734]

I’ve been having this issue with my 4.0 97 6cyl. Swapped transmissions and flex plate and torque converter and it was quite and then it started again. This time I’m just noticing that one motor mount looks way off center then the other and maybe the engine and trans are not perfectly aligned even though they are bolted together could that even be possible. ?

[@aurian18]

There are dowel pins connecting the transmission housing and engine block together so you cannot misaligned there. It is possible you have a bad motor mount and could replace it, but that is not likely to be the cause of this noise.

[@1mcobb]

Same issue and noise! Flex plate isn’t cracked. And bolts are good

[@ProVisionColor]

Dang. Sounds like we are in the same boat. I pulled the oil pan and checked bearing and things and I can’t seem to figure out what it is. I couldn’t see any play in the rear piston, but my buddy who’s replace quite a few engines in different Jeeps is still thinking it’s piston slap. Who knows. Other than the noise, it’s running great!

[@BertMackFilm]

Throw out bearing sleeve and the fork combined? My first guess was the fly wheel or torque converter bolts as well. Other than that it it sounds like connecting rod issue. 1999 to around 2003 I believe had issues with pistons cracking causing all sorts of issues.

[@ProVisionColor]

@@BertMackFilm Still totally could be something to do with the pistons. I checked the rod bearings on the rear two-three connecting rods and they were all fine and within spec. So it could be something higher up, like the pin where the rod connects to the piston, or something like that. Unfortunately I couldn’t really check those with the crank in the way. I couldn’t see any play or gaps between the piston skirt and the cylinder wall, but again, tough to tell from below. Everything was tight when I wiggled it by hand, but that’s obviously not all that precise or accurate. ;)

[@BertMackFilm]

@@ProVisionColor no cylinder wall scoring from a sloppy pin rubbing the skirt down the wall? This sounds almost sexual lol

[@ProVisionColor]

@@BertMackFilm Bwaha! Not that I could see...

[@deegaw11]

Hey have you figured what the issue is? Mine just started doing this. Used to do it only on cold starts then goes away when warmed up but now it’s always there and goes away when I rev it.

[@Danny-rc6qr]

My 99 cherokee make the same exact noise. Started making that sounds randomly one day after running quite for a while

[@ProVisionColor]

Did you happen to find out what caused your sound?

[@Danny-rc6qr]

@@ProVisionColor no, i have good oil pressure and normal temps, it runs perfect and ive been taking it on long trips every weekend.

[@ProVisionColor]

@@Danny-rc6qr Same here. No problems with oil pressure or loss of power. I pulled the oil pan a while back and checked a few of the main bearings just in case, they were fine. Rod bearings were tight too. Clearances all looked good. Super weird, lol.

[@Danny-rc6qr]

@@ProVisionColor really weird. Just changed the oil, no metal flakes or anything suspicious

[@ProVisionColor]

@@Danny-rc6qr This sound definitely is weird! There are so many people who are hearing the same sound with no obvious source. Have you checked your flexplate for cracks or loose bolts?

[@otter5555]

my 96 xj 4.0 makes the exact same noise. tc bolts are tight and flex plate is NOT cracked or loose. runs perfectly. screw it, just gonna run it.

[@ProVisionColor]

Right?! These 4.0s seem to be noisy, but they just keep running! Good luck!

[@cawhitby]

Did you ever figure this out? Mine has the same exact noise.

[@wharris14]

My 06 started making this noise recently. It goes away when I push in the clutch and sometimes when I hit the gas 🧐

[@ProVisionColor]

Have you checked your flywheel for cracks?

[@stewartwilson4204]

I am currently troubleshooting the same problem on my 2003 TJ. I notice it's worse when clutch is engaged. Did you ever find out what it was?

[@ProVisionColor]

Sadly, not yet. Mine’s an automatic though, so no clutch. Have you checked your fly wheel for cracks? If the sound gets worse when the clutch is engaged, that would make me wonder if something is wrong with the flywheel.

[@jacobraber4588]

Did you figure it out

[@dylanstoner1821]

Ever figure this out?

[@ProVisionColor]

Sadly, not yet. But it’s still running like a champ, just sounds weird! Lol.

[@jonredcorn862]

@@ProVisionColor Flex plates cracked.

[@ProVisionColor]

@@jonredcorn862 Could be. Haven't ruled that out yet. I'm also thinking maybe a bad thrust bearing. I've got some copper shavings in the oil, but the rod and the main bearings look good.

[@gabrieleluciani4686]

Hi, my 99 wj 4.0 makes the same noise when in R,N,D but disappear in P...do you think I have a transmission issue? Or "just" flexplate??

[@ProVisionColor]

Hmm, that's a tough one. Out of my expertise, sorry. There's been a lot of people who know more than I do that have said that if the rattling sound changes from P to R/N/D then it's most likely a cracked flex plate, but I have no experience with that. Mine stays the same regardless of the gear. Have you tightened your flex plate bolts? Checked your trans fluid?

[@acappellahymns]

Did you ever figure out what this noise was on yours?

[@ProVisionColor]

Nope, not yet. I'm leaning towards the classic 4.0L piston slap issue. Check out the thread over at wranglertjforum.com, tons of info there. Just search for the thread by TheGoblin (that's me), and you will find pages and pages of helpful info from the folks there, even full engine tear-downs. Good luck!

[@jberzin3]

Keep us updated! ;)

[@ProVisionColor]

Will do! Nothing yet. (I've been enjoying the summer, so I haven't been working on this, lol.)

[@Pudgeliath]

Ive got the same noise. Ive checked everything people suggested it could be I even had work done on the head and lifters, replaced everything under the valve cover and still the same damn sound.

[@jberzin3]

Thanks mate! Time to wait for some brave person who now rebuilds the bottom part ;)

[@ProVisionColor]

@@Pudgeliath Dang! For real? It wasn't the lifters? That's probably my next thing to check. Did you check the main and rod bearings? What about the flexplate? Sorry to hear it man!

[@ProVisionColor]

@@jberzin3 Lol, agreed. I pulled the oil pan last year to check the bearings, that was honestly a bit terrifying. But everything that I could see checked out just fine. The clearances were good on the main and rod bearings, so that wasn't the problem. No broken piston skirts, and couldn't see any play in the pistons themselves as they moved in the cylinders (looking for piston slap). I didn't check the thrust bearings though, I should've checked them while I had everything off, because I really don't want to do it all again, lol. Good luck man!

[@jorgenoneya5382]

Flex plate bolts coming loose

[@ProVisionColor]

Thought about that too, but I’ve pulled them and retightened them twice with no improvement. Used lock tight too. I actually spray painted the heads of the bolts to see if they were striking the dust cover, but nothing. No marks in the paint.

[@ClanOxyL]

How does your exhaust manifold look against your engine ?? I hear some people thought they hear a knocking from the bottom of the engine from a rear manifold leak and I noticed that my jeep is missing the rear manifold bolt or its broke and it is definitely leaking there decently. I doubt this is my issue but would be good to know if yours is leaking at all or not.

[@ProVisionColor]

Yeah, I've heard the same thing from a few folks. Someone suggested this over on wranglertjforum but a few people came back saying it couldn't be the problem for me because of the way my noise isn't there immediately upon startup instead it shows up about 30 seconds later. A cracked manifold would mostly likely go the other way around, it would be noisy at first when the metal is cold, and then the sound would get quieter as the metal of the manifold heats up and seals itself better. I have checked for leaks in my manifold and haven't heard anything. It's a really confusing sound. I'm leaning towards a stuck lifter or piston slap, but those could act the same way a cracked manifold does - louder at startup and then get quieter as the metal flexes or oil arrives. So many options... lol. Thanks!

[@5588rasta]

Im having the same issue and my check engine light is flashing did you ever figure it out?

[@ProVisionColor]

Dang! Flashing check engine light? That doesn’t sound good. Sorry, mine is still clanking away. Haven’t figured it out yet.

[@efraimperez2726]

Dang it is? Mine is doing the same thing I took it to a mechanic and they think it's the rod bearings. How many miles have you driven yours?? Has it gotten worse over the years?​@@ProVisionColor

[@ProVisionColor]

@@efraimperez2726 I checked the main and rod bearings on mine, and they were all in spec, so I’m pretty sure mine is piston slap. I only drive it around town, so it only gets a thousand miles a year. I just tried some Engine Restorer with my last oil change and it is amazing how much quieter it is now. I’m not recommending using that, because every additive has its down sides, but I thought I would try it and see what happened.

[@efraimperez2726]

@@ProVisionColor gotcha I was thinking of doing an engine restore as well. That's for replying!

[@TheMysticMethodCardReadings]

@@efraimperez2726 You bet. Good luck!

[@ryanfloresflerr]

Our Jeeps sound exactly the same! I've been driving it for over a year and no change. Tried retorquing those flexplate bolts, replaced timing chain and no improvement. You ever figure it out?

[@ProVisionColor]

Sadly, not yet! Checked some main and rod bearings and they were good. Didn't look like any play in the thrust bearing, but that could still be a possibility. It's really strange, huh? There are a lot of people with this same noise but no real answers yet. It still could be a lifter, it's just weird that the sound seems to come from the bottom end of the engine. Guess it's time to pull the valve cover and see what I can find! There's a really good conversation about this issue over at wranglertjforum.com. Just search for threads by The Goblin (that's me), and you will find it. Lots of good info from people much smarter than me! Lol. Good luck with yours!

[@sinclairlewis2061]

Wrist pin?

[@ProVisionColor]

@@sinclairlewis2061 Definitely an option. Just haven't wanted to pull the head to check.The heads on these 4.0L engines are super heavy.

[@paulkardous7581]

Hi. My 98 sounds exactly the same. Only 75k original miles. Did you ever find out what it is? I’m still looking and hoping is the flexplate

[@ProVisionColor]

Hey. Sorry, nothing yet. Have you tried engine restore? One guy just tried that and it cleared up his sound, apparently it was a lifter for him.

[@paulkardous7581]

@@ProVisionColor I’ve been told by a mechanic that it could be a lifter for me too as I have an intermittent rough idle/ a bit lower compression on cyl#1. Valve not sealing properly. But the noise definitely comes from the same area as yours, right where the engine connects to the flexplate

[@justtocomment5128]

@@paulkardous7581 I have the same issue on my 2010 wrangler. When the engines cold the noise isnt there but the longer i drive the more prominent it gets. If i haven't driven it in a while the noise isnt there initially but comes after a couple drives. At lower rpm the noise is louder and when i accelerate more the noise goes away. Could this be a cracked flexplate or loose bolts?

[@swanson3k]

anything new with this?

[@ProVisionColor]

Nothing yet. Still clanking away.

[@swanson3k]

@@ProVisionColor damn. 🥴

[@jonathanpoulin6150]

update? please

[@ProVisionColor]

Still the same for me. Noise is still there, but I'm just living with it for now. Lots of folks with the same issue, but not very many answers. Quite a few have had the noise for 100k+ miles and never had any major problems. Check out this thread to see what others have done: kzbin.info?event=comments&redir_token=QUFFLUhqbG8wNi1raGxnTnI2WVJkLXpTN3ZhNmFVS0xUUXxBQ3Jtc0tuYndnX0xVTENUcWlNSVMwd1R1LUNPeUxkeVNzUjg4OUZrc0pzSDdzS0VzbHB0VkhBb29RLWtWY2YzaE54WW5iVXhvTXhvVFdEbkE5aFZINXhNenBvdEEtSVg4eE9pXzBsMzZHc0Y4YlN1bXZnVi1law&q=https%3A%2F%2Fwranglertjforum.com%2Fthreads%2Fhelp-diagnosing-engine-knock.33602%2F&stzid=UgwDBMHmmXup8kKxnXV4AaABAg

[@alale923]

@@ProVisionColor i bet the flex plate is cracked and cannot be seen from the inspection cover. Im abt to yank the tranny on my xj bc im so sick of this noise. Have had a new flex plate in the garage for like a year. And my noise is 100% coming from the bell housing.

[@ProVisionColor]

@@alale923 Oh man! Please let me know what you find! I'm leaning towards piston slap, but it totally could be the flex plate. I just haven't wanted to pull the tranny.

[@dakotagist7526]

Have you checked the oil pump?

[@ProVisionColor]

Not specifically. Oil pressure has been fine though. Think it could be the pump? What should I look for?

[@dailying3049]

My 2.5L makes that noise

[@jonathanpoulin6150]

update ? (help me)

[@brianvillasenor74]

My 2.5 yj makes the same noise too!