Connecting Rod Play

[Ol' Bessie's Keeper]

Hey there everyone! 2002 Jeep TJ 2.5

First time posting in a while, but a lot of my time and attention when to getting my MJ running rock solid! Now that she's doing okay, I turn my attention back to Bessie. I had a head gasket blow, and got her put back together. Once I started her up, she was LOUD. It wasn't just lifter noise, it was hard to listen to. Definitely possible to be a blend of exhaust leak, lifter noise, but also bottom end noise.

Now, for peace of mind, I dropped the oil pan, and found the timing chain tensioner to be in ruins, absolutely shredded (I'll be replacing it tomorrow). So I'm now thinking the timing chain may be the source of the majority of my racket...but I'm not fully convinced. Anyone who has a good eye and ear... before I button up the oil pan, is this too much play in my connecting rod bearings? No play vertically it doesn't seem, but they do knock back and forth. Are they shot?

https://photos.app.goo.gl/S5HazPYBjuiBgSYdA

 

[macleanflood]

It's easy to pull a bearing cap...pull one and take pictures. And honestly if you're in it this far why not just roll in a new set of bearings and confirm with plasti gauge.

-Mac

 

[Ol' Bessie's Keeper]

It's easy to pull a bearing cap...pull one and take pictures. And honestly if you're in it this far why not just roll in a new set of bearings and confirm with plasti gauge.

-Mac

You know how it goes. Plenty of gurus on here that have seen this stuff left and right for decades. Figured I'd try to not disturb the bottom end if the consensus was that the play being heard was fine. But I have no problem popping in new bearings!

 

[Ol' Bessie's Keeper]

Tried to pop one of the caps off to check bearing life, but of course she's pretty wedged on there. I'm gonna for-go trying to pop all them off and check, again unless they seemingly have way too much play.

I'll check the timing chain tomorrow and then crank the engine to each cylinder's down stroke to check wrist pin slop.

 

[MichaelGH]

Hey there everyone! 2002 Jeep TJ 2.5

First time posting in a while, but a lot of my time and attention when to getting my MJ running rock solid! Now that she's doing okay, I turn my attention back to Bessie. I had a head gasket blow, and got her put back together. Once I started her up, she was LOUD. It wasn't just lifter noise, it was hard to listen to. Definitely possible to be a blend of exhaust leak, lifter noise, but also bottom end noise.

Now, for peace of mind, I dropped the oil pan, and found the timing chain tensioner to be in ruins, absolutely shredded (I'll be replacing it tomorrow). So I'm now thinking the timing chain may be the source of the majority of my racket...but I'm not fully convinced. Anyone who has a good eye and ear... before I button up the oil pan, is this too much play in my connecting rod bearings? No play vertically it doesn't seem, but they do knock back and forth. Are they shot?

https://photos.app.goo.gl/S5HazPYBjuiBgSYdA

Mine had very similar side to side rod movement. Mine was actually rebuilt professionally and had that sort of movement. My 2.5L ran like a champ for years with it. No excessive noise…

I’d get that timing set replaced and try to start it again…

 

[Ol' Bessie's Keeper]

Mine had very similar side to side rod movement. Mine was actually rebuilt professionally and had that sort of movement. My 2.5L ran like a champ for years with it. No excessive noise…

I’d get that timing set replaced and try to start it again…

Sorry for the ignorance, but I have a quick question.

The timing chain was replaced like five years ago or so. Cracked open the cover today, and yeah, the tensioner grenaded itself. Again, shocked my chain didn't snap also because it does have some play, but maybe this is normal? It seems to be enough play at TDC to insert a tensioner? Is the play in the chain supposed to shift as the crank turns? Do I need a new chain? Timing is still on point.

 

[sab]

is this too much play in my connecting rod bearings?

https://photos.app.goo.gl/S5HazPYBjuiBgSYdA

First - do you know you can get the OEM service manual right here on this forum? If not, it's in a thread on the top "sticky" section of the TJ Resources forum.

Now, once you have that, go to page 9-15 (pdf page 786), and you'll find this:

Is that more than 0.019" in your video? If so, then it's too much.

The timing chain was replaced like five years ago or so. Cracked open the cover today, and yeah, the tensioner grenaded itself. Again, shocked my chain didn't snap also because it does have some play, but maybe this is normal? It seems to be enough play at TDC to insert a tensioner? Is the play in the chain supposed to shift as the crank turns? Do I need a new chain? Timing is still on point.

Once again, refer to the manual. Refer to page 9-62 (pdf page 833), and you'll find this:

Now, in my experience that's an odd way of determining when to replace the timing chain, but that's the official method. On the 4.0L, you just measure the deflection of the chain (remove tensioner, press on the chain halfway between the sprockets, and if it moves 1/2" or more, you replace it). That's more typical from other engines I've worked on.

 

[macleanflood]

Probably don't need a new chain...but if you're in there I'd throw a Melling at it. Comes with the nylon tensioner anyways.

-Mac

 

[MichaelGH]

Sorry for the ignorance, but I have a quick question.

The timing chain was replaced like five years ago or so. Cracked open the cover today, and yeah, the tensioner grenaded itself. Again, shocked my chain didn't snap also because it does have some play, but maybe this is normal? It seems to be enough play at TDC to insert a tensioner? Is the play in the chain supposed to shift as the crank turns? Do I need a new chain? Timing is still on point.

View attachment 483437

View attachment 483438

View attachment 483440

You can try just a tensioner, but you are already right there. May want to put the entire setup on. Peace of mind, if nothing else…

Just make sure you have every little piece of broken material out of there. No sense in getting the old bits in your oil pickup…

 

[Ol' Bessie's Keeper]

Went ahead and replaced the timing chain since I was already there and the slop did seem significant. Buttoned everything back up and she's now purring minus some small lifter tick. Of course with one thing fixed, another shows itself.

Getting a lovely exhaust rattle, sounds like it's the CAT heat shield, but don't know why this is happening out of nowhere. I am hoping it is the heat shield, as I can't get the CAT monitor to flip via the drive cycle. Hopefully the honeycomb isn't knocked out of place and the CAT is falling apart...The muffler also started spitting fiberglass...those damn Thrush Mufflers don't last long...I had it installed in 2019!