Timing chain slack question...

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

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.

I will check that out today.

Video sounds like piston slap.

Shredded piston skirt. Found metal pieces in bottom of pan. https://youtu.be/-RuBrNds90c ?.....

I will be pulling the pan some time this weekend. Let you know what I find.

md21722 said:

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.

Click to expand...

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.

Don't worry about the chain count.

FTW

FTW II

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.

gray_penguin said:

Mine is a 4cyl for what its worth.

Click to expand...

FYI, The 4.0L doesn't have a tensioner.

The 2.5L does indeed have a tensioner. A six cylinder has a snubber.

mechbullxj said:

The 2.5L does indeed have a tensioner.

Click to expand...

Go back and re read my post.

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.