Knocking sound at idle

Sounds like a timing chain. Either the tensioner or the rubber guide have let go and are slapping against the aluminum cover.
Does it go away when accelerating, then comes back after returning to idle a few seconds later? Easy enough job. Might be time for one anyway.
 
On mine the rubber guide(isolator) broke and was slapping against the aluminum cover making a similar noise that was difficult to pinpoint. Very loud though.
 
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This is a cold start and then rev just up to 1k
Gollywomper said:
Sounds like a timing chain. Either the tensioner or the rubber guide have let go and are slapping against the aluminum cover.
Does it go away when accelerating, then comes back after returning to idle a few seconds later? Easy enough job. How many miles on motor? Might be time for one anyway
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That's exactly what it does. Not to doubt you or any other members but I don't see how the timing chain would make the sound underneath the motor though. I mean you can hear it all around but it seems to originate from underneath
 
BTW guys, I took a video with the camera on my phone and turns out it's too long to share with y'all lol. I'll see if I can find something that matches the sound and share it. Otherwise, it's cold and late and I ain't going back outside til tomorrow
 
ChristopherD said:
This is a cold start and then rev just up to 1k

That's exactly what it does. Not to doubt you or any other members but I don't see how the timing chain would make the sound underneath the motor though. I mean you can hear it all around but it seems to originate from underneath
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Exactly where mine sounded like it was coming from. Guessing the aluminum just transfers the noise that way.
 
My 2.5low makes a very loud mechanical ticking sound at idle, matches lifter tick, loud enough that people have commented to me at gas stations that my engine is broken, it’s always done it, had it for 33k (currently 163k) now zero issues.

I’m 99% sure it’s entirely manifold leak, scares me every now and then on real cold mornings.

Same experience as you it really is only heard at idle. I don’t have your oil pressure issue though, I never drop much below 40.

Does your Jeep tick while you accelerate? When the engine gets to op. temp it isn’t very noticeable at idle anymore, is this your case?
 
Fughuert said:
My 2.5low makes a very loud mechanical ticking sound at idle, matches lifter tick, loud enough that people have commented to me at gas stations that my engine is broken, it’s always done it, had it for 33k (currently 163k) now zero issues.

I’m 99% sure it’s entirely manifold leak, scares me every now and then on real cold mornings.

Same experience as you it really is only heard at idle. I don’t have your oil pressure issue though, I never drop much below 40.

Does your Jeep tick while you accelerate? When the engine gets to op. temp it isn’t very noticeable at idle anymore, is this your case?
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Once the rpms come up any at all or you out it in any gear the noise stops. Doesn't matter if it's cold or warm
 
This is cold start, RPMs at 1000 then let off and dropped to idle which is when the sound gets loud. Still smooth as can be at when giving it any throttle at all
 
It takes much less time to just check the chain than to debate it. Pull the distributor cap, put a breaker bar on the crank and turn both ways. Done.
 
What could possibly be loose inside the oil pan but not be a piston or rod or bearing or something like that? Could the oil pump come loose? Or maybe the pickup screen? Or something along those lines?
 
The rubber isolator that keeps the chain from slapping on the cover had broke on mine. The noise sounded like it was coming from the rear oil pan area. Hard to diagnose via forum. Have to start digging into it.
 
It's the flexplate bolts. Figured it'd be the easiest thing to check. Three of the four bolts we're loose and there's one that looks like somebody crossthreaded it and left it, or it's back itself so far out it hit something and bent itself. So I tightened the other three just for s&g's and the sound changed but is still there. So what do I do about the bent/crooked one?
 
How long are the bolts? Seen an xj video and they seem short. Short enough to where this bolt I'm referring to may not even be started in the threads actually
 
That's a wrap for this thread. Ended up that bent bolt didn't mess up the threads so, a replacement bolt and the other three tightened up with a dab of loctite and the noise is gone. Thank you all for your advice. I'm sure I'll need it again. Hopefully later than sooner
 
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