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jhc7399
April 15th, 2015, 09:03
When I bought my 99 xj 4.0 in March of 14 I noticed it had a knock at idle so I picked up a 96 block, had it rebuilt and a friend an I installed it 3-4 months ago. I have started tearing down the old engine to see if there is anything obvious that could be causing the knock. The top half looks great, everything is tight, a good coating of oil on everything so it looks like the pump is still getting plenty of oil up there. I pulled the timing chain cover and noticed how loose the timing chain is and the plastic/rubber "guide" was cracked in and half. If you watch the two videos I am trying to figure out if that loose timing chain could have been causing my noise. The noise when away at a higher idle and the flex plate was fine. I have not got to lower half of the engine yet. Going to pull the pan and see how that looks this weekend. I have a competent re builder close but it will be $1400 to get it rebuilt. If I can get off cheaper and it doesn't need a rebuild I am all for it.

Listen and tell me what you think,
Thanks!



Noise:
https://youtu.be/dhCuqgkhuxA

Timing chain:
https://youtu.be/xx3aZoM-jM0

md21722
April 15th, 2015, 10:14
The FSM states:

"If the timing chain deflects more than 12.7 mm (1/2") replace it. The correct timing chain will have 48 pins. A chain with more than 48 pins will cause excessive slack."

I am not sure about your noise.

jhc7399
April 15th, 2015, 10:25
I will check that out today.

Talyn
April 23rd, 2015, 07:06
Video sounds like piston slap.

mechbullxj
April 23rd, 2015, 08:11
Shredded piston skirt. Found metal pieces in bottom of pan. https://youtu.be/-RuBrNds90c ?.....

jhc7399
April 23rd, 2015, 11:05
I will be pulling the pan some time this weekend. Let you know what I find.

md21722
April 23rd, 2015, 14:13
The FSM states:

"If the timing chain deflects more than 12.7 mm (1/2") replace it. The correct timing chain will have 48 pins. A chain with more than 48 pins will cause excessive slack."

I am not sure about your noise.

An update to this: Sometime around 1997 Chrysler switched to chains with about 64 pins. My 1997 has the newer style chain even though the 1997 FSM indicates a 48 pin chain. I doubt my chain was previously replaced. The chain I pulled off my 1997 is a Morse. The dealer replacements are also Morse.

Talyn
April 23rd, 2015, 17:06
Don't worry about the chain count.

mechbullxj
April 24th, 2015, 10:55
http://s1081.photobucket.com/user/mechbullxj/HPLAPTOPHOMEUSE/Pictures/Libraries/DSCN0070_zpsnhhobuv7.jpg?1429897548361&1429897549133

mechbullxj
April 24th, 2015, 11:11
http://photobucket.com/albums/j348/mechbullxj/HPLAPTOPHOMEUSE/Picture/Libraries/DSCN0070_zpsnhhobuv7.jpg?1429899568832&1429899569560

FTW

mechbullxj
April 24th, 2015, 11:40
:mad:http://s1081.photobucket.com/albums/j348/mechbullxj/HPLAPTOPHOMEUSE/Picture/Libraries/DSCN0070_zpsnhhobuv7.jpg?142990016494&1429900167284

FTW II

gray_penguin
April 24th, 2015, 20:49
I have a 99 also, and for a long time I had a knock that I could not pin down. One night There was a loud pop and the engine started running rough. Turned out the knocking was the timing chain and tensioner hitting the timing chain cover. the Pop was caused when the tensioner finally came apart and a piece of it found its way under piston #1 and broke the skirt off one one side of it.

Mine is a 4cyl for what its worth.

Talyn
April 25th, 2015, 05:32
Mine is a 4cyl for what its worth.
FYI, The 4.0L doesn't have a tensioner.

mechbullxj
April 25th, 2015, 11:12
The 2.5L does indeed have a tensioner. A six cylinder has a snubber. ;)

mechbullxj
April 25th, 2015, 12:50
http://s1081.photobucket.com/user/mechbullxj/media/DSCN0066_zpsiszac7og.jpg.html?o=0

Talyn
April 25th, 2015, 18:02
The 2.5L does indeed have a tensioner. Go back and re read my post.

mechbullxj
April 25th, 2015, 19:54
Your right a 4 cylinder has a chain tensioner. Was trying to post a picture of shards from my 4.0L #6 cylinder. Also a 1999.