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chatter sound

F

Financialmistake96

NAXJA Forum User
Location
San Diego
96 xj auto trans has developed a chatter like sound. I came across many post about backed off flex plate bolts. Bolts are tight no visual cracks on the plate. I then replaced the starter because I thought it wasn’t Disengaging. The sound continues. I’m Stumped. Any help would be greatly appreciated. Thanks in advanced.
 
When does the sound occur, and when does it not occur ? Hot/cold, fast/slow, in gear/in neutral, accelerate/decelerate, etc. ?

What is the conditon of the motor mounts, the transmission mount, and the exhaust hangers ?
 
The 96 XJ is notorious for the catalytic converter failing.
The cat material breaks loose from the housing and causes
a rattle. There was a recall on it several years ago.
 
Also common for the exhaust to rattle against the crossover member that supports the transmission. Typically caused by bad motor and trans mounts.
 
Sorry for the late reply, it’s still an ongoing issue. I’ve checked the exhaust it’s not hitting anything nor does it even shake much. I looked at all the mount mentioned above and yes they have seen better days but nothing noticeable wrong to be concerning. The symptom occurs at its worst on cold starts. I can feather the throttle some to get the rpms up and the noise goes away. When rpms come back down to idle that dreaded sounds comes back. I can drive let’s say 10 mins and let the vehicle idle and the sound is still there but much Quieter. Do cracked flex plates make noises all the time or can it come and go? How can I check my cat?
 
The way I checked my cat was simply by listening to it.
When it rattled at idle I would get under it as far as possible
on both sides, and listen. The sound was more pronounced
on the passenger side near the cat. That confirmed it for me.

If your 96 still has the original cat, I would strongly suspect it
to be the source of the rattle. As I said, defective cats were a
common enough problem for there to be a recall on them for
the 96 model year. If yours has been replaced, then maybe
something else...
 
Check the engine to trans bolts, seen those come loose before. Flex plate cracks right around where it bolts to the crank, not sure if you can see that from the inspection area. Cats on a lot of xjs are a failure point. You can take a mallet a smack it a couple of times, if the catalyst has come loose or broken you should hear it rattling around in there.
 
Noisy lifters, piston slap, cracked piston skirt, possible but not likely flex plate issues. Inspect as necessary.

Cat converters have a service life of about 150,000 miles, replace as necessary.
 
Just re read your posts, it really sounds like textbook rod knock, that's exactly how mine sounded for months before it finally threw #2 rod. Throw a bottle of Lucas in there and I bet the noise goes away for a while. Good news is that a lot of people have had good luck just dropping the pan and putting in a new set of rod bearings.
 
Could also be lower timing cover bolts backing out and hitting the balancer, had that problem with my 01, very unlikely though. Just thought I’d throw that out there for y’a.


Sent from my iPhone using Tapatalk
 
My XJ sounds a bit like a diesel during warmup after first start of the day. It goes away completely within about 10 minutes, so I've been assuming its lifter chatter. Perhaps the OP has a stuck lifter? Not sure if that's common for XJs.
 
Hold on max. Rod knocks do NOT go away when things warm up.
Next time you start it and it's clattery, shut it off and wait 10 seconds or so. Restart it. Still ticking?
BTW, what brand oil filter are you using and which oil?
 
cruiser54 said:
Hold on max. Rod knocks do NOT go away when things warm up.
Next time you start it and it's clattery, shut it off and wait 10 seconds or so. Restart it. Still ticking?
BTW, what brand oil filter are you using and which oil?
Click to expand...

Yeah, that's my understanding too about rod knock. Its that unclewolverine said he had the same noise as mine, and eventually a rod departed from the crank.

I'll try tomorrow morning on first start.

Amsoil Premium Protection 10W-40.
 
I fought with the "diesel sound" on warm up for months trying different things under the impression that it was a lifter. Did it worse the colder the temp, you can check the old threads yourself. Then one day it didn't go away after warm up, halfway through the mail route it was seriously knocking, 20 mins later, rod through the side. My dad nor I had never seen a rod knock that went away when warm, but the proof is in the pudding. Still had 60 psi of oil pressure right before it blew too, super weird.
 
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