Help! Xj knocking on startup -
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Unread 09-15-2014, 10:07 AM   #1
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Join Date: Sep 2014
Location: Jacksonville, Florida
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Help! Xj knocking on startup

Hello my jeep xj has recently been knocking when I start it up. It seems to quiet down after about 5 seconds. It also knocks when I put it on park in my driveway. I recently changed out the water pump, and took it to get the oil changed with high mileage oil. It has 160,000 miles on it and the oil pressure is normal. Not sure what it is? Please help.

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Unread 09-15-2014, 10:28 PM   #2
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1993 XJ Cherokee 
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Could be anything from a loose or cracked flywheel to a bad lifter, don't forget the catalytic convertor can rattle when bad as well, pin point the knock and report
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Unread 09-16-2014, 09:00 AM   #3
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Push against the distributor cap with your hand. Try wiggling it a bit- may require a bit of force. See if the knock change
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Unread 09-16-2014, 09:10 AM   #4
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1998 XJ Cherokee 
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you're in Florida, so running heavier oil may be an option
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Unread 09-16-2014, 08:59 PM   #5
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1990 MJ Comanche 
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Location: Prescott, Arizona
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What brand of oil filter did you use?
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
My Jeep Technical Photos
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Unread 09-16-2014, 09:27 PM   #6
AZ Jeff
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2014 JK Wrangler 
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Knock, or a metallic rapping?

Knock generally implies a deep solid sound, and most engine issues that create that sound don't go away after a few seconds.

A metallic rap or tap sound is not uncommon on engine startup with worn hydraulic valve lifters.

Which type of sound do actually have?
1992 XJ -- stock (RIP)
2000 XJ -- lots of basic mods. Sold to fellow forum member. I miss it.
2014 JK -- the project is just starting!
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