anyone have a knocking sound in a 4.0 engine? - Jeep Wrangler Forum

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Old 06-08-2011, 10:20 PM   #1
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anyone have a knocking sound in a 4.0 engine?

it doesnt knock like a rod or berring. more of a hollow sound. ive been told exaust and normal piston slap.. any info?

also wanting to look into getting rid of death wobble? im not sure if i have it. i get to about 57 mph and the jeep shakes and then goes away for a sec then comes and goes like that only past like 57 mph.. any ideas on that?

then also doing a brake job this week.. any ideas on a certain pad brand or type as far as ceramics or what ever.
and how hard are the drum brakes to do?

thanks yall (:
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Old 06-08-2011, 10:27 PM   #2
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sorry can't help u but i think i have the same noise going on so i am subscribing to this thread. I know for sure i have an exhaust leak somewhere just haven't looked too hard for it.

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Old 06-08-2011, 10:37 PM   #3
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The knocking could be lifter tick, which is common in pretty much every 4.0. Does it always make the sound? Or just on warm up? It could also be much worse, It's unlikely but it could be a broken piston skirt.

Another simple test is next fill up put a little bit of premium gas in to rule out pre-detonation (knock/ping).
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Old 06-08-2011, 10:39 PM   #4
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Jeeps make all kinds of noises, just do a you tube search for engine noises.
Piston slap, exhaust leaks, lifter noises, and so on.

As for DW, you'll know it when it happens. It will pucker you right up. Usually occurs if you hit a bump, or a dip in the road a certain way. Yours sounds more like a tire balance or tire problems.

Do a search on brake pads, there are a few out there that folks swear by.

Drums aren't bad, especially if you have the spring tools. Have to watch, some had the old mopar style lining. Instead of a full lining on the shoes, they have 2, with a space between em. If the lining is worn out, it can groove the drums to the point that the only way to remove the drum is to back off the adjuster all the way.

And if you are doing it yourself, do one side at a time, that way you can peek at the other side when reassembling, to confirm how it goes back together.
97 Sahara, 74 Renegade, 72 CJ5, 55 Willy's (the Beast) Boss 302, 6:34 gearing, Bose 901 speakers.
God I miss that Jeep. Forgot the kinda Jeep, 80 SX4.
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Old 06-08-2011, 10:56 PM   #5
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Im assuming I have some piston slap going on. Noise only there when I start the jeep and gone after about a minute or two. My Yj had a lifter tick and was loader when started till the oils made it's way up to the top of the engine, but I could still hear it a little while driving. Both are pretty common as far as the 4.0
I have 160,000 on my 01 so I'm not really worried about it. She is pretty quite after warming up.
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Old 06-08-2011, 11:41 PM   #6
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yeah its only until the engine is warm and then the "knock" goes away. the dealer said normal piston slap for those motors. idk and there is a slight lifter tick but not very much. the other noise is differant and cant find a good sounding youtube video to get an idea lol
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Old 06-08-2011, 11:55 PM   #7
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The noise is most likely lifter tick. Very Common. Should hurt anything. You can have this fixed by replacing the lifters. It's around 500-600 bucks at a jeep dealership.

The death wobble - replace your steering stabilizer and make sure your tires are well balanced. Should fix it right up. I recommend an OME (Old Man Emu) steering stabilizer. Best bang for the buck. I replaced my stock with a OME steering stabilizer when I got the death wobbles... fixed it right up. Hasn't come back.

Good Luck
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Old 06-09-2011, 09:46 AM   #8

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Originally Posted by Shelby427 View Post
Jeeps make all kinds of noises,

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