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Discussion Starter · #1 ·
Tonight I noticed a knock in my 98 TJ that I can only hear at idle. It's a 4.0l auto. I've had this jeep for about a month and this is the first time I've noticed this. It's only at idle, if I give it a little gas it goes away, and I can't hear it at all while driving. It doesn't make any difference whether it's in gear or not. I read some posts on another forum that said this was a common problem, and most said it was nothing to worry about and that it was "normal" but it was only XJ owners. Has anybody else heard of this?
Thanks,
Scott
 

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How many miles are on it? Time for plugs maybe? Vacuum leak? Oil change?
 

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The 4.0 is notorious for an injector tick, and, 97 thru 99 TJ's were also infamous for cracked exhaust manifolds.
 

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Discussion Starter · #4 ·
First off, thanks for the replies! It's got 89,000 miles on it. I went out this morning and drove it around the block and it seemed fine, didn't really get warmed up though. I'm going to change all the fluids and plugs and check the exhaust manifold this week and see if it helps. If it's "injector tick" is it something to be concerned about?
 

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The 4.0 is notorious for an injector tick, and, 97 thru 99 TJ's were also infamous for cracked exhaust manifolds.
Injector tick? Never heard of it. :confused:
 

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Which is it, a knock or a ticking? You first described it as a knock, now everyone's talking about ticking... a far different symptom. A knock at idle can be serious, I'd have a good engine mechanic listen since you could have a rod bearing going bad. How's the oil and oil level?
 

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Discussion Starter · #8 ·
Definatly a knock. Comes and gos and only when it's hot. Took to my mechanic, couldn't reproduce it. He checked it over pretty good and said everything seemed fine, but if it came back to bring it back in. Oil is new and is full, Mobile 1.

Thanks!
 
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