Help Diagnosing Engine Knock


rdu-jeep

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Hey, sorry guys. Sorry I haven't updated in a bit, I've been busy enjoying the spring weather with the top off. :) My family and I have taken a ton of quick impromptu drives out through the farmlands lately just to enjoy the scenery. It's been awesome. We took a picnic out to Antelope Island (a large island in the Great Sale Lake that you can drive to) just this weekend and got caught in one heck of a summer rain storm! We laughed the whole way back while getting pelted with warm rain in a topless Jeep. It was a blast. (the funniest part was when I was so confused as to why the windshield wipers weren't working and then I finally realized it was because the water was on the INSIDE of the windshield! Lol!). Anyway, some responses and updates:


Ok, thanks. That's what I'm thinking too. It has only happened once since and it only happens for a second and then goes right back up. Now that I know where the sensor is located, I'm sure I bumped it when I was messing with the spark plug rail thing. I will check it out to see if I messed with the connection.


Ok, thanks for the input the too. It was freaking me out a bit since I had messed with some main bearings, but my nerves have calmed a bit now. I was kind of thinking the same thing about the Rislone. Can't imagine it's much different than SeaFoam really. Thanks!


Hey! Welcome aboard! This has been quite a journey, I hope you can find some answers for your problems here too. If you find anything that I haven't found yet, please post it here! I did change my timing chain which definitely helped the performance of the Jeep, but didn't clear up the knocking sound. I didn't expect it to since my knocking sound is coming from the rear of the engine whereas the chain is at the front. If your knocking sound is at the rear, then I would guess the chain is not the cause either. If you are going to change it and don't want to remove your radiator, get the pulley tool from Harbor Freight. It has a much shorter bolt that will fit in between the crank pulley and the radiator, the ones you can rent from O'Reilly and Autozone have a really long bolt and can only be used if the radiator is removed, assuming your setup is the same as mine.



Totally agree here. Mine definitely added to things, just wasn't the core issue (haven't found that yet).


Yep. This is the truth. Changed mine (glad I did), but the sound remains.

Update: I had to take it in to have a seal replaced on the transmission that was leaking. I had AAMCO take a look at things for a different problem I was having (lurching = solved = bad PCM/TCM), and they changed the shift solenoid thinking that was the problem. The seal they put in was leaking so they fixed it for me. So I finally got it back and I think I'm ready to start the next phase of investigation. Honestly guys, I'm leaning towards an exhaust leak, probably from the manifold itself. I found another video on YouTube of a guy with a really similar noise and it turned out to be an exhaust leak for him. So I think I will do the "shop-vac-in-the-tail-pipe" trick and see what I can find with a bottle of soapy water. I did some spying underneath and I think I can see a spot on the manifold, right at the rear, where it looks like exhaust has been escaping (black marks around the manifold). So it may blown a gasket, or maybe the manifold itself is cracked. That could explain why the sound is loud when the engine is cold and it almost completely goes away now when things warm up after a few miles. If the metal gets hot and expands and closes up the leak, that may explain it.

So I will try that and see what I find.

I think I will also take off the valve cover and see what I can find underneath, see if there is any play in the rockers, like you guys mentioned.

It's also time for another oil change to see if there is still glitter in the oil. I'm really hoping it will clear up after a few changes and it was just residual crap that was trapped in the carbon over 18+ years, possibly from the chain wearing. Although, the glitter definitely has a copper tone to it and I'm not sure what would be copper in the engine...

Send it to Blackstone Labs! They'll tell ya.
 
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The Goblin

The Goblin

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Hey guys. It’s been a while. Sorry about that. This pesky TJ is going to be the death of me.
After I buttoned things up with the oil pan, the Jeep started “chugging” at very low speeds. I didn’t notice it while parked, but once I put it in reverse and started rolling, it felt like the engine was missing almost. It was really weird.
Not sure what happened, maybe a I bumped something.

It came and went for a while until about a month ago when I drove it out on the freeway to and from work (70 miles round trip), and came home with some codes: p0340 and p1391
Bad camshaft sensor, and “loss of cam or crank.”

No bueno.

The next day I only drove it a few miles and it died on me right on the road. I got it started and got back home to more codes, a bunch of spark plug codes.

I replaced the spark plugs and the coil rail (the gaps were HUGE!), that got rid of those codes, but the camshaft codes remained. Drove it half a mile and it died again.

The dealer I bought the Jeep from told me they changed the camshaft position sensor, so I thought I would start with replacing the crankshaft sensor. Didn’t fix it.

So today I dug into the CPS and the drive. Got it to top dead center on a compression stroke and pulled the drive out. It looked practically brand new so I'm sure the dealer did actually replace it. From what I could tell, the gear on the camshaft looked good too (thank goodness!).

Here’s the odd part, when I went to put the new drive and sensor in, the sensor doesn’t point directly backwards, toward the firewall, instead it is angled towards the engine block. I have the adjustment cap on it, so I know the drive is aligned. I just don’t know what this means.

Is it ok that it doesn’t point straight backwards? It was pointing straight back when I took the old one out. Could that be why it was throwing the code? Could I have knocked it out of alignment when I was messing around with the coil rail way back when I had the oil pan down? (I pulled the rail off and sort of stuffed it down where the CPS sensor is).

Could I have messed something up when I changed the timing chain?

This has been one big adventure, that’s for sure.

Here is a picture of the alignment cap on the drive, you can see how it angles towards the block
8F53AF99-C675-40CC-9086-A9082F1E2B9A.jpeg
 

Skylinessuck

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I don't know what that tool is, but my quick read of you getting things lined up issue looks like you are by a tooth where the cam sensor and cam meet. Am I reading your issue right?
 
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The Goblin

The Goblin

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I don't know what that tool is, but my quick read of you getting things lined up issue looks like you are by a tooth where the cam sensor and cam meet. Am I reading your issue right?
Yeah, seems about right. That tool came with the new cam sensor/OPDA. It's basically designed to keep the OPDA in the correct alignment while installing it down into the engine. I think the old ones just had a hole on the side that you could stick a cotter pin through or something like that, to keep it from spinning when you installed it. This is just a cap that goes on top of the OPDA until you get it installed, then you take the cap off and put the cam sensor on in its place.

I couldn't seem to even back it up one tooth, it always seemed to go in at this orientation. But I will try again. Maybe I just wasn't turning it back far enough.

I guess I should add that I am posting this here on this thread for posterity sake, in case anyone else who is dealing with the same engine clanking noise I am, and is following this thread, ends up encountering the same issue (if it is indeed because I knocked something askew).

I had wondered if maybe a bad OPDA was the cause of my metal "glitter" in the oil issue, but this looks really new. I suppose it could have been the old cam sensor the dealer replaced, if it was worn out. Maybe the metal filings got caught up in the carbon in the engine and got released when I SeaFoamed it. Who knows? It's a thought.
 
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The Goblin

The Goblin

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Ok... I'm an idiot. I just went outside, pulled the OPDA out, backed it up one tooth, adjusted the oil pump slot, and the drive slid right into place with perfect alignment. Lol.

I put everything back together, fired it up, and no codes! Hallelujah.

So because of this fun adventure, the Jeep now has all new spark plugs, a new coil rail, new crankshaft position sensor, and a new camshaft position sensor. This dang thing is going to be completely brand new by the time I'm done with it. ;)

Still not sure what made all this go bad at once, unless I inadvertently messed something up when I was tinkering around underneath trying to figure out this clanking sound (which is still there by the way, loud and clear).

Anyway, hope everyone is enjoying the fall weather!
 

Skylinessuck

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That's what I thought. Off a tooth. I did the same thing with my dizzy the first time. Glad you got it running! And no noises to boot! So I'm trying to remember without rereading the whole thread, but the noise turned out to probably be the loose timing chain? Sludge and metal probably got knocked loose from the seafoam and was old?
 

bromel

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Oct 11, 2018
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That's what I thought. Off a tooth. I did the same thing with my dizzy the first time. Glad you got it running! And no noises to boot! So I'm trying to remember without rereading the whole thread, but the noise turned out to probably be the loose timing chain? Sludge and metal probably got knocked loose from the seafoam and was old?
He still has the original noise. It's almost certainly a lifter bleeding down given how much he has replaced so far.
 

fourpointzero

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OP, I really appreciate you posting all this information. My TJ is close 200k and has this similar ‘rattle’ towards the bottom, back. Im really thinking, considering similar circumstances of yours, it could be a manifold or exhaust leak. Maybe I’m just desperate at this point. I had compression checked and under the oil pan visually inspected. Everything checked out great.

So, knowing the these exhaust manifolds are flawed (least that’s what I recall reading) maybe it is in fact an exhaust leak of some type?
 
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The Goblin

The Goblin

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That's what I thought. Off a tooth. I did the same thing with my dizzy the first time. Glad you got it running! And no noises to boot! So I'm trying to remember without rereading the whole thread, but the noise turned out to probably be the loose timing chain? Sludge and metal probably got knocked loose from the seafoam and was old?
Yeah thanks for calling it out! I seriously laughed when I just twisted it a little further back, and all was well. Lol. It ran fine today, no codes. Very happy for that.

The clanking noise is still there, sadly. I have a buddy that suggested piston slap, but when I inspected the pistons underneath, I couldn't see any play in the pistons or gaps between the pistons and the cylinder walls. Everything looked tight. But, hard to tell for sure since things can change once things warm up, right? The noise isn't there when I first turn the engine on, it takes about 30 seconds to show up, so I'm guessing it has something to do with temps or once the oil gets pumped up into the engine. Or, it still could be the darn flex plate. ;)

I do think the metal came from the SeaFoam cleaning things out. The glitter has all but gone away with the last few short-interval oil changes. We will see what happens with a normal 3000 mile oil change.
 
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Unspokenfor

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Your last video sounds similar to the sound mine was making. It wouldn't do the ticking sound until around 30 seconds after the engine started up, or when first revving it a little.

This is the sound mine was making, and it ended up being lifters, which I got replaced.

 
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The Goblin

The Goblin

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OP, I really appreciate you posting all this information. My TJ is close 200k and has this similar ‘rattle’ towards the bottom, back. Im really thinking, considering similar circumstances of yours, it could be a manifold or exhaust leak. Maybe I’m just desperate at this point. I had compression checked and under the oil pan visually inspected. Everything checked out great.

So, knowing the these exhaust manifolds are flawed (least that’s what I recall reading) maybe it is in fact an exhaust leak of some type?
Hey you bet man! Everyone here has been so much help, I'm really in their debt. Bunch of really great folks. I'm hoping this journey can help others who have the same issue, if I can ever figure out what the problem is. ;)

Exhaust leak is definitely on the list of possibilities. I found a video on YouTube of a guy who had a similar knocking sound and it ended up being a nasty crack in his exhaust manifold. Worth checking out.

I'm pretty much down to: piston slap (but couldn't see any evidence of it), stuck lifter (but it seems too low down??), flex-plate, or exhaust leak. Lol, that's quite a list!

But, while I'm working to figure that out, I'm definitely having plenty of other problems creep up to keep me busy!
 
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The Goblin

The Goblin

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Your last video sounds similar to the sound mine was making. It wouldn't do the ticking sound until around 30 seconds after the engine started up, or when first revving it a little.

This is the sound mine was making, and it ended up being lifters, which I got replaced.

Lifters huh? Did you have a shop replace them? The heads on these engine are so dang heavy, that I'm not really looking forward to that job. I suppose I really should take the valve cover off and inspect the rocker arms, rods, etc., to see if anything is stuck.

Glad you got your figured out!
 

Unspokenfor

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Lifters huh? Did you have a shop replace them? The heads on these engine are so dang heavy, that I'm not really looking forward to that job. I suppose I really should take the valve cover off and inspect the rocker arms, rods, etc., to see if anything is stuck.

Glad you got your figured out!
Yeah a shop that just does engine/transmission work. At first he was 100% sure it was a loose rocker or rod, but after inspection didn't see anything wrong with them.

I was sure it was a broken piston skirt, so luckily it ended up not being that. Goodluck on your search.

I still sometimes hear the sound for the first 5 seconds on engine startup, which im guessing is normal since they aren't getting oil yet.
 

Airjunky

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Haven't been on this thread in a while and you've progressed a bit...... Sorry it's still a problem for you.
Mine has been great. Has about 5k miles now, including a couple of good wheelin runs where it did really good.
Not really sold on these 4.0 liters. I have talked to a half dozen guys with problems and they're all over the place.
 

fourpointzero

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@Unspokenfor you got my attention when reading that yours “wouldn't do the ticking sound until around 30 seconds after the engine started up...” but mine sounds more like a rattle or small diesel than what yours sounds like in that video you posted.

Appreciate that you’ve got some video evidence up for reference. Cheers
 
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The Goblin

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Yeah a shop that just does engine/transmission work. At first he was 100% sure it was a loose rocker or rod, but after inspection didn't see anything wrong with them.

I was sure it was a broken piston skirt, so luckily it ended up not being that. Goodluck on your search.

I still sometimes hear the sound for the first 5 seconds on engine startup, which im guessing is normal since they aren't getting oil yet.
Oh man! So glad it wasn't a piston skirt!

Was your sound coming from underneath the engine though? It seems to me that a rocker or rod would make noise on the top? Mine is definitely louder underneath.
 

Unspokenfor

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Oh man! So glad it wasn't a piston skirt!

Was your sound coming from underneath the engine though? It seems to me that a rocker or rod would make noise on the top? Mine is definitely louder underneath.
It definitely seemed to me like it was louder underneath the engine, or at least had more clarity.
 
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The Goblin

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Haven't been on this thread in a while and you've progressed a bit...... Sorry it's still a problem for you.
Mine has been great. Has about 5k miles now, including a couple of good wheelin runs where it did really good.
Not really sold on these 4.0 liters. I have talked to a half dozen guys with problems and they're all over the place.
Glad to hear yours is running well! I can definitely say this 4.0 has taught me a ton. ;) I've learned more about the inner workings of an engine than I ever thought I need to know! lol.
 
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ToughToaster

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Glad to hear yours is running well! I can definitely say this 4.0 has taught me a ton. ;) I've learned more about the inner workings of an engine than I ever thought I need to know! lol.
Has there been any progress on this? Mine has the exact same noise and curious if its a cracked header or not...