Help Diagnosing Engine Knock

[The Goblin]

Pulling the cam and visual inspection is the only way I can think of. They aren't as delicate as the other bearings btw. I was worried when I nicked mine but was told by several engine builders not to worry. Cam walk (end play) and crank walk should be concerns and checked for sure. Should be able to do that with a pry bar from underneath.

I wouldn't run diesel oil either. That Rotella thing has been Internet lore forever since before they started decreasing zddp in those oils as well. Plus different detergent packages. Run something formulated for a gas engine. Like I said, I recommend Valvoline VR1 but there are other good options out there.

That timing chain is freaking toast! That last bearing you posted doesn't look good either. I wouldn't reinstall that personally. And if one bearing looks like that, I'd plan to check them all. Do your have a local machine shop you can show them to?

Ok, I won't worry about the cam bearings too much then. I will see if I can check for end play while I'm checking the crank shaft. Thanks again for the thoughts on the oil! I'm going to definitely replace the chain, got the new one in today, and I'm going to replace that bearing I posted a picture of. Something nasty got in there and I definitely don't want to put it back on the crank.

Button it up and replace the chain, I would not go further into it personally. That chain was really bad, fix it and then decide what to do next after testing it out.

I'm seriously about to that point, lol. I'm going to replace that one main bearing and check the thrust bearing, but then I think I'm done underneath there. Everything is super tight and all my tests are turning out good so I don't think there is much reason to dig too much more into it. If nothing new shows up while I'm checking/replacing these last few things then I think I will just replace the chain and move on to the next possibility which is lifters or flex plate.


Any opinions on bearing metal type? I ordered bearings and they are the tri-metal kind. After they came in I realized that there are aluminum (bimetal) too. I've seen multiple opinions on both, do you guys have opinions on what is best to use in our 4.0 engines?

 

[The Goblin]

Got the bearing type answered on another thread. Sounds like tri-metal is the norm nowadays so I will stick with what I bought.

 

[The Goblin]

Button it up and replace the chain, I would not go further into it personally. That chain was really bad, fix it and then decide what to do next after testing it out.

Hey pagrey, honest question for you. Do you think that main bearing will cause me any trouble if I just put it back in? I checked it again last night and it is a .001 undersized cap. I'm struggling to find a single .001 main bearing replacement. None of the auto shops can even order that size and the ones I ordered are standard; and I had to order the entire dang set for just one half a bearing...

So I'm wondering what your thoughts are since you commented to just put it back in. The bearing definitely has some small gouges in it up on the end by where the cap bolts back onto the block, but the rest of it super smooth. There's no copper or brass showing through. The gouges look pretty new and they look like something hard got in there and scratched it up but is gone now (piece of dirt? Metal maybe?).

So I'm really at a place of making a decision on what to do. The clearances are all great with the plastigauge and the only problem are those gouges on the one bearing. Am I setting myself up for trouble later on if I put this bearing back in and just move on? Or am I worrying too much?

It seems to me that this is what the bearings are partially designed to do, and the manual says that if the clearances are good, then there's no need to replace them. I'm just not sure what to do and I'm curious what your thoughts are on this.

Thanks!

 

[The Goblin]

I guess the other option is to replace that lower insert with a standard size insert. When I checked the clearance on that main, the plastigauge showed .001, and according to the FSM the acceptable range is .001-.003 with .0015-.002 being ideal. If I put a standard bearing on it, worse case is it would open it up to .002, right? Since the standard is actually thinner than the .001?

I just hate having to open an entire pack of bearings ($100) just to only use one insert...

My problem is that I tend to over-think things a lot and cause myself more stress than I need to. Not sure if this is one of those times or not. Lol.


It's really hard to see here, but this is a shot of the plastigauge. It fills the .001 area nicely.

 

[pagrey]

I'd run it and not think twice about it. I'm just some guy on the internet though, it's your engine and they ain't cheap. My opinion is that if you keep everything clean you wont have problems. Sometimes taking things apart frees up stuff that can cycle through and damage things, there really is no sure answer. I probably wouldn't do a mismatched main bearing. The only thing I'd consider replacing is big end rod bearings as a set and yours seem fine.

 

[The Goblin]

I'd run it and not think twice about it. I'm just some guy on the internet though, it's your engine and they ain't cheap. My opinion is that if you keep everything clean you wont have problems. Sometimes taking things apart frees up stuff that can cycle through and damage things, there really is no sure answer. I probably wouldn't do a mismatched main bearing. The only thing I'd consider replacing is big end rod bearings as a set and yours seem fine.

Ok, thanks man. I really appreciate it. I'm just weighing my options at this point. I think I'm leaning towards just changing the timing chain and then closing things back up. The clearances all seem fine and that seems to be what matters most according to the FSM (as long as there is nothing too crazy going on with the bearings or journals).

I still need to check the thrust bearings, but if they are ok, then I think I'm moving on. Time to start investigating the lifters and the flex plate more in depth.

Thanks for your input!

 

[The Goblin]

Holy crap. Changed the timing chain today... wouldn’t wish that job on ANYONE! Lol. Didn’t want to remove the radiator, and managed to be successful at that. Word for the wise though, if you are going to do that, get the wheel puller set from Harbor Freight, NOT the one you can rent from O’Reilly or Autozone; theirs won’t work because the main bolt/pin you use to pull the harmonic balancer off is too long and won’t fix in the space. The one from Harbor Freight was only $15, had more bolt attachments, the actual foot thing is flat and usable on both sides, and the main bolt is only 5 inches so it fits perfectly!
https://www.harborfreight.com/bolt-type-wheel-puller-set-62620.html
I did run into one weird thing though, the sprockets for the crank are WAY tight. I watched all these videos and people just pulled their old sprocket off with no trouble and slipped their new ones on with plenty of play. Not mine. I had to pry the old one off bit by bit, and then I had to hammer the new one on by going in circles around the sprocket with a rubber hammer. It would only move a fraction of an inch at a time. Weird. But it’s exactly what the stock one was, so it must not be THAT weird.

Here’s a pic of the inside of the timing chain cover. Honestly, it doesn’t look too bad and that black guide is still in there...

it looks like the chain was scratching a little bit, but not like I expected to see.

It does look like the chain may have been hitting the outside edge of the cover though:

So, not sure what to think there. I am really curious what this cover looked like before the seafoam treatment however. I’ve seen some really nasty ones in some videos so I can’t help but wonder what this one looked like.

I’m going to clean the cover up on Monday and get everything back installed. I spent a few hours scraping the old gasket off the block (no fun...) but it’s super clean now! And then I will tackle the stuff underneath. Still need to check the crank and see if the thrust bearing is bad. If it’s good, then I think I’m going to close things up and move on to the next possible item on the list.

Oh, and no oil slinger installed, is that odd? The FSM mentions one, but it also mentions this really weird chain tensioner with springs and locks instead of the basic black piece of plastic we have.

should I put one in? Or just leave it the way it was?

Thanks guys!

 

[RaymondT]

Holy crap. Changed the timing chain today... wouldn’t wish that job on ANYONE! Lol. Didn’t want to remove the radiator, and managed to be successful at that. Word for the wise though, if you are going to do that, get the wheel puller set from Harbor Freight, NOT the one you can rent from O’Reilly or Autozone; theirs won’t work because the main bolt/pin you use to pull the harmonic balancer off is too long and won’t fix in the space. The one from Harbor Freight was only $15, had more bolt attachments, the actual foot thing is flat and usable on both sides, and the main bolt is only 5 inches so it fits perfectly!
https://www.harborfreight.com/bolt-type-wheel-puller-set-62620.html
I did run into one weird thing though, the sprockets for the crank are WAY tight. I watched all these videos and people just pulled their old sprocket off with no trouble and slipped their new ones on with plenty of play. Not mine. I had to pry the old one off bit by bit, and then I had to hammer the new one on by going in circles around the sprocket with a rubber hammer. It would only move a fraction of an inch at a time. Weird. But it’s exactly what the stock one was, so it must not be THAT weird.

Here’s a pic of the inside of the timing chain cover. Honestly, it doesn’t look too bad and that black guide is still in there...
View attachment 156049

it looks like the chain was scratching a little bit, but not like I expected to see.

It does look like the chain may have been hitting the outside edge of the cover though:
View attachment 156050

So, not sure what to think there. I am really curious what this cover looked like before the seafoam treatment however. I’ve seen some really nasty ones in some videos so I can’t help but wonder what this one looked like.

I’m going to clean the cover up on Monday and get everything back installed. I spent a few hours scraping the old gasket off the block (no fun...) but it’s super clean now! And then I will tackle the stuff underneath. Still need to check the crank and see if the thrust bearing is bad. If it’s good, then I think I’m going to close things up and move on to the next possible item on the list.

Oh, and no oil slinger installed, is that odd? The FSM mentions one, but it also mentions this really weird chain tensioner with springs and locks instead of the basic black piece of plastic we have.

should I put one in? Or just leave it the way it was?

Thanks guys!

The 4 cyl uses that chain tensioner and that rub strip pictured.

 

[The Goblin]

The 4 cyl uses that chain tensioner and that rub strip pictured.

Oh, right on. Thanks. I won’t worry about it then!

 

[The Goblin]

AAAAAAAAAAA!!!! I just broke one of the tiny little bolts of the timing chain cover off IN THE BLOCK!

It broke with barely any pressure on it... Ugh...


Any suggestions for getting it out of the block?

 

[The Goblin]

And I’m one blessed guy!

It was sticking out of the block and a simple pair of vice grips did the job.
Onward and upward.

 

[fourpointzero]

That was close! Vice-Grip, the OG. I need to get one. The fakes are just passable.

 

[The Goblin]

That was close! Vice-Grip, the OG. I need to get one. The fakes are just passable.

Right?? I was SO relieved to see that stud sticking out of the block!

I learned a very valuable lesson with that experience... make sure you are checking between FOOT pounds of torque and INCH pounds! Whoops....

Well I finally got everything back on after changing the timing chain. When cleaning the chain cover I definitely found some really rough spots in the middle that were “shiny” as if they had been recently worn from the chain rubbing on them. That could account for the metal slivers I found in the oil.

I checked for play in the crankshaft yesterday with a pry bar and nothing. There was barely any perceptible movement at all. So it looks like the thrust bearings are doing their job.

I am going to change out that one main bearing that had the scoring in it. After closer inspection I can see small particles of foreign material embedded in the lower bearing cap at the end of each scoring mark. So I don’t want to put that on and risk it scoring the shaft. Had to order the .001 undersized bearings in though because it seems none of the normal parts stores carry that size. Should be here Monday.

So I think I’m going to change that one bearing and then button everything back up and move to the next option. I am pleased that the crankshaft and bearings seem to be just fine and that gives me some peace of mind to keep going while investigating some “less-lethal” sources for the knocking sound.

while I have easy access to the flex plate bolts, I think I’m going to paint the top of them so I can see if they are indeed hitting the cover or not. If the paint gets scratched off, then I will know.

I will keep you guys posted.

 

[The Goblin]

Got that one main bearing replaced. I will admit, that was quite nerve-wracking. I just don't like working that closely to the crank shaft. Getting the top bearing out wasn't too bad, but get getting the new one back in was a little bit more tricky. I'm glad I changed it though. There wasn't really any wear to worry about, but both top and bottom caps had definite scoring and foreign particles embedded in the surface of the caps. Didn't want that to become a much bigger problem in the future if those particles started scratching the journal.

I had a standard top cap and a .001 undersized bottom cap. I checked the clearance again with Plastigauge after installing the new caps and everything was right on. It was frustrating that I had to special order the .001 caps though. They were like $22 a set at Summit Racing. The more frustrating part is that I had to order the standard caps in an entire set which cost just under $100! Just to use ONE HALF circle! So if anyone needs some standard caps, let me know, we can work something out.

This little tool definitely helped with that top bearing.

I rechecked the play on the crank shaft and there really isn't any perceptible movement at all. I visually expected the thrust bearings and they look just as thick as the replacement ones. So at this point, I'm ruling the thrust bearings out. They were a definite possibility in my mind based on what I had read from others who had experienced similar symptoms, but alas, not for me.

Still no idea where all that glitter came from, unless it was the timing chain.

So I think I'm about ready to put the pan back on and move on. But before I do that, any advice on anything I should do before buttoning things back up?

Any last minute things to check? (Even if not related)

Also, since it's been sitting now for a few weeks with the pan off, is there anything I should know before I start the engine up after putting things back in place?


I am going to run some ZPPD in it this time. I bought some Mobile 1 Super Synthetic and some Lucas Zinc additive that I will use for the first oil I put in after this job. Then I think I will change the oil a few times (as recommended here) after short intervals (apprx 500 miles or so) and see if the glitter goes away.

Thanks guys! You have all been a TON of help!

 

[SkylinesSuck]

Oil pump while you are in there? What kind of oil pan gasket will you use? Shine you light up in there and inspect the cam lobes for wear as best you can.

 

[fourpointzero]

Looking forward to the results of your efforts.

 

[bromel]

This is a fantastic thread that I'm sure will be useful for Jeepers for years to come. Keep up the great work! Are you going to take the head off to replace the lifters? Really curious to see how that process goes.

 

[SkylinesSuck]

I wouldn't pull the head at this point before I put it all back together and see if there is still an issue (unless you can visually see a problem with the cam lobes from below). It's much more involved to pull the head and very little labor would overlap with what he's currently doing.

 

[rdu-jeep]

This is a great thread! I have the same sound and if I decide to dive in, this will be a fantastic reference thread.

Have you ever heard of Blackstone? They will analyze your oil very cheap. You fill up their small container and ship it to them for analysis. Just follow their instructions so you get a good sample.

 

[The Goblin]

Oil pump while you are in there? What kind of oil pan gasket will you use? Shine you light up in there and inspect the cam lobes for wear as best you can.

I really debated about changing the oil pump since it's right there, but I think I'm going leave it. My oil pressure has been good so I think I'm good. That being said, I am fighting the mental battle of "what if it dies the week after you button everything back up." Lol. But, now I know that I can get in there and change it if I have to, even if I don't want to. . I'm using a fel-pro gasket, it was the one O'Reilly ordered for me. Hope it's a good one.

I actually have been looking at the cam lobes the last few times I was under there, just to see if they look ok. As far as I can tell, they are still all there and quite pronounced, no flattening that I can see off hand. But I will do a more thorough check before I put the pan back on. Thanks for the suggestion.

Looking forward to the results of your efforts.

Thanks! Me too!

This is a fantastic thread that I'm sure will be useful for Jeepers for years to come. Keep up the great work! Are you going to take the head off to replace the lifters? Really curious to see how that process goes.

Thanks bromel! I love to hear that. I'm a teacher at heart, so if what I'm going through can help others, that does my heart good.

I think I will wait for a bit before tackling anything so large as removing the head. . This has been an exhausting experience so if the "knocking" sound is still there after putting this all back together (which I fully expect it to be), I will give it a bit of running time with some short-interval oil changes to see how things play out.

I wouldn't pull the head at this point before I put it all back together and see if there is still an issue (unless you can visually see a problem with the cam lobes from below). It's much more involved to pull the head and very little labor would overlap with what he's currently doing.

Yeah, thanks man. I think I'm going to run it for a while and see how things shake out. I'm going to put some ZDDP in the oil and see if that helps (if it's a lifter issue). It still could be the flexplate as well so, as I mentioned earlier, I'm going to paint the heads of the torque-converter bolts to see if they are hitting the dust cover (if the paint gets scratched off, then I will know).

This is a great thread! I have the same sound and if I decide to dive in, this will be a fantastic reference thread.

Have you ever heard of Blackstone? They will analyze your oil very cheap. You fill up their small container and ship it to them for analysis. Just follow their instructions so you get a good sample.

Hey rdu-jeep! Glad this thread can help! These guys are full of so much good advice and they have been a ton of help to me, so I hope you can gain some insight through all this as well. Hope it helps you out with whatever your issues ends up being.

I haven't heard of Blackstone, but I did run into a video on YouTube of a guy showing how to do in-frame main bearing replacements on a farm tractor (very helpful video) and he mentioned having an oil analysis done as well. Said they could really tell what's going on inside an engine just from the analysis, but I don't think he mentioned a name. This might really be worth doing, especially if it's only a few bucks. I will admit, I think I'm a little afraid of what the answers might be.


Thanks guys. I'm going to try to get things back together tonight and tomorrow so I will post an update of what I find. Also, there have been some definite tools that have come in handy on this journey so I will post those and my experiences with them as well in case they can help anyone else in the same situation.

Keep on rollin'!