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Unread 08-01-2012, 01:23 PM   #1
portcityXJ
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Strange "popcorn" engine noise

My jeep is a 95 XJ, 4.0 with just over 250k miles. I owned it for 6 1/2 years now and have taken good care of her. Recently i noticed i had a knock on start up and shut down (maybe 2 - 3 knocks each start up/shut down). After the jeep gets me to my destination and i put the trans in park, there is a metallic "popcorn" sound coming from the engine. its audible in the jeep, but loudest underneath. There does not seem to be any rhythm to the noise.

If i rev the engine, the noise goes away. The engine runs great, and i have not noticed the noise while running on the highway, only slightly at red lights, but mostly after a parked warmed engine.

Ive done a little research and most say its a flexplate bolt issue, however after watching some youtube videos, im not so sure. Ill see if i can get a video of it soon.

Any ideas? this is my way to work/school/life so i really need it as top notch as possible. Thanks.

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Unread 08-01-2012, 01:26 PM   #2
portcityXJ
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probably the closest i could find to give you an idea. except mine seems to vanish when the gas is pressed.
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Unread 08-01-2012, 03:31 PM   #3
portcityXJ
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my video. pay no attention to the engine chatter. turn the volume up to hear the clunking.
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Unread 08-01-2012, 07:17 PM   #4
portcityXJ
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bump for the night crew
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Unread 08-01-2012, 07:59 PM   #5
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http://www.cherokeeforum.com/f51/how...ocking-125547/
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Unread 08-02-2012, 01:09 PM   #6
redjeep83
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Might even be piston slap. Might have bad rings. Check out Jeepstrokers.com and check out the cheep Cherokee episodes of Trucks! There is an episode that they start it and it slaps for a few seconds and goes away as it warms up.
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Unread 11-26-2012, 12:46 PM   #7
el_magico
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Was there any resolution to this? My 95 XJ is doing the exact same thing. After a long trip and short rest, upon start up mine will knock like that until I rev it a little, possibly causing the flexplate to balance out by centrifugal force. Same thing a red lights from time to time, just a little on acceleration quiets it. but inside the Jeep it sounds like some one is trying to pound their way in from the floor board. At first I thought that it might be a rod knock but it doesn't knock all the time. I'll try to check it this week.
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Unread 11-26-2012, 02:33 PM   #8
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Originally Posted by el_magico View Post
Was there any resolution to this? My 95 XJ is doing the exact same thing. After a long trip and short rest, upon start up mine will knock like that until I rev it a little, possibly causing the flexplate to balance out by centrifugal force. Same thing a red lights from time to time, just a little on acceleration quiets it. but inside the Jeep it sounds like some one is trying to pound their way in from the floor board. At first I thought that it might be a rod knock but it doesn't knock all the time. I'll try to check it this week.
Just do the flexplate bolts. can't hurt and might help.

What brand of oil filter are you using?
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If you own a Renix Jeep, you'll want to check this out. >

An index to over 25 write-ups can be found in Post #1.

Cruiser's Mostly Renix Tips
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Unread 11-26-2012, 02:36 PM   #9
el_magico
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Just do the flexplate bolts. can't hurt and might help.

What brand of oil filter are you using?

I really hope that's all it is! And I hope its not too late that the flex plate has cracked or something.

I use Amsoil filters.
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Unread 11-26-2012, 02:43 PM   #10
portcityXJ
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Quote:
Originally Posted by el_magico
Was there any resolution to this? My 95 XJ is doing the exact same thing. After a long trip and short rest, upon start up mine will knock like that until I rev it a little, possibly causing the flexplate to balance out by centrifugal force. Same thing a red lights from time to time, just a little on acceleration quiets it. but inside the Jeep it sounds like some one is trying to pound their way in from the floor board. At first I thought that it might be a rod knock but it doesn't knock all the time. I'll try to check it this week.
It ended up being a loose flexplate. I tightened the bolts up but that only lasted a few days. I ended up removing the bolts completely, one at a time, and reapplying thread lock and reinstalling them. That seems to have cured the noise. A dead giveaway is when you pull the cover, you see that the edges of the flex plate are shiny from contact.
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Unread 11-26-2012, 02:53 PM   #11
cruiser54
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See Post #5 for a link to a great write-up on doing the flexplate bolt repair.
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Originally Posted by chris87xj View Post
If you own a Renix Jeep, you'll want to check this out. >

An index to over 25 write-ups can be found in Post #1.

Cruiser's Mostly Renix Tips
Refresh*Connections*Before*Replacing*Components
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