A pocket full of jingling bottle caps...

[cshontz]

Engine question here. My 4.0L is around 130k, and it "ticks" at idle. I'm not new to the 4.0L, and I know they're prone to doing so - especially when they get up there in miles. However, it seems a little more prevalent under load at low RPMs than I've experienced in the past.

So basically:

1. At idle, subtle, and seemingly innocuous ticking. No big deal. Life goes on.
2. Highway driving, under load at a low RPM, what sounds like an assortment of beer bottle caps jingling in one's pocket, and dissipates after a downshifting to a more appropriate gear. A tad more worrisome.

You know when you're sick, and you Google your symptoms, and WebMD tells you that you're dying? Well, I Googled my symptoms, and the Internet revealed (in all of its wisdom) that my engine is moments away from exploding. In fact, my Jeep is probably on fire in my garage as I'm typing this. I don't buy it.

All I know is:

• Power is adequate.
• Oil pressure is good.
• Exhaust looks clean.

I could have an exhaust manifold leak, which would account for the slight ticking. However, the low-RPM, metallic jingling sounds a bit more mechanical. It doesn't sound critical, it just sounds like my Jeep is getting old. Although I would at least like to know what it is, and attempt to remedy it.

How would you guys approach this? Is there an additive you would recommend? Maybe a more viscous oil? Is there something in particular I can do to diagnose?

 

[AndrewDM]

The low-RPM metallic jingling could be "pinging" or detonation. You could try a higher octane fuel to see if that stops what you are hearing. Pinging can also be caused by carbon buildup in the combustion chambers. Additives will be of little use.

-Andy

 

[jeepdreamer]

^that^ and maybe try running some acetone with each fill up.

 

[TOI]

is it a renix model 4.0? i know my renix doesn't like new oils without zinc in them. i always add a bottle of zinc substitute and it quiets down the rocker tack

 

[88Xj]

Rosella 5w40 is what I run.

 

[Jim K in PA]

Chris - Is it the original engine? If so, then it could be a number of things, but most likely not the OPDA issue in the later TJ/LJ. If it sounds like a light metallic click, then it may be valve lifter noise. If it is more of a heavier sound, it could be piston slap. 4.0Ls all seem to have some degree of slap when colder, but it usually goes away when warm. Lifter noise usually does not go away. Tough to tell without hearing it.

 

[marshal]

what year is it? in 05 they went to a different ECM and the injector tick is much more prevalent

 

[cshontz]

Thanks for responses, all. It's a 2001 XJ original 4.0L.

Jim, it's definitely a light metallic clicking. Has absolutely no bearing on whether its hot or cold. I'm leaning toward lifter noise. I think all advice I've received in this thread has been good advice. I should definitely clean whatever carbon build-up I can. I should definitely switch to a 40W. I always have a shop do it, so not sure what's in there now - probably a 30W synthetic.

Another noise at idle is a very slight diesel-ish rattle. It's also very subtle.

You wouldn't hear my 4.0L running and be like, "my god, what is wrong with that thing?" - to the untrained ear, I'm sure it doesn't sound bad. I'm just trying to recognize symptoms of potential problems. Want to make sure my car's heart is in great shape, because I still have a lot of adventures planned with this rapidly aging XJ.

 

[reece146]

The diesel sound at idle could be the classic 4.0 cracked exhaust manifold (chuff, chuff, chuff).

 

[Brandon Libby]

Would it be possible to post a video up?

 

[cshontz]

The diesel sound at idle could be the classic 4.0 cracked exhaust manifold (chuff, chuff, chuff).

I've had a couple of cracked manifolds on my former TJ, and they were always like "fffttt, fffttt, fffttt". This feint diesel noise is like a rattling gurgle. While on vacation with my parents this past fall, my dad noted, "Your engine sounds 'tinny'." - I just nodded and was like, "Yeah, the miles are getting up there."

In retrospect, I should've been like, "Let's pop the hood and find out why!" - which would've been a fabulous bonding experience.

Would it be possible to post a video up?

Thought about it. I may try it, but I don't think the issues are loud enough. I think it'd sound fine and you guys would think I've lost it. Admittedly, every little rattle drives me nuts. The other day, the drone from my poorly worn front tires was causing my dashboard vent slats to resonate, which I put an end to very abruptly. If the change in my center ashtray dish is rattling, I stuff it full of tissues and napkins.

Now I love my Jeeps - I've never driven anything else. I know they'll do this. However, I've never liked it. After about 10 years of use, it becomes a losing battle.

While I'm enjoying speculating with everyone in this thread, I'll likely have my shop take a look at these issues next time it needs to go in for something. It's just frustrating not knowing. I'm usually in-tune with everything that's going on with my Cherokee.

 

[Robert Bills]

Have you tried a stethoscope to isolate the noises? A piece of heater hose works almost as well. Just be careful to stay away from the fan, belt, and other moving parts.

 

[X-plorenow]

Is it metallic or electric sounding? Electric could be a bad plug arcing. Had that before.

 

[1stDeuce]

A stretched timing chain or loose tensioner (wait, I don't think the 4.0 has a tensioner...) will make a diesel like rattle. So will loose bolts (even just one) that hold the torque converter to flexplate. Or a flexplate crack. On an '01, it's not likely that your exhaust manifolds are cracking, as they're the cast ones. The earlier tube ones were prone to that, but not the cast ones so far as I know. It could be pinging lightly because there's too much carbon built up somewhere. Try filling with mid-grade next time just for fun and see if the low rpm highway "bottlecap rattle" is gone.

Or just keep driving it and see what let's go. Probably nothing will. I know the '04-06 OPDA's are notorious for going out, but the earlier ones either died early, or they just keep going and going...
Good luck!
C

 

[reece146]

Cast manifolds are just as bad for cracks IME.