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Unread 07-13-2010, 05:14 PM   #1
jeepgirl_90
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1990 FSJ Cherokee 
 
Join Date: Jul 2010
Location: PA
Posts: 2
1990 jeep xj engine knocking

any ideas as to why it's knocking or how I can get the noise to go away ?

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Unread 07-13-2010, 07:38 PM   #2
whiskeyNcoke
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1985 CJ7 
 
Join Date: May 2010
Location: Olympia
Posts: 32
Quote:
Originally Posted by jeepgirl_90 View Post
any ideas as to why it's knocking or how I can get the noise to go away ?
It is knocking because it wants in. Maybe it is too cold at night for it, and it wants to be in the warm house. One way to get it to stop would be to answer the door. Maybe put a blanket on it.


In all seriousness, you gave us absolutely zero info to go off of. In order to diagnose what's wrong over the net, we will need as much detailed info that you can possibly give us. We can only base the "knocking" sound, off of what you say. For all we know, it could be as simple as a lifter tapping, and you are saying it is knocking. I'm not trying to call you dumb, but you need to elaborate a little.
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Unread 07-15-2010, 05:11 PM   #3
whiskeyNcoke
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1985 CJ7 
 
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Must not want our help.....

or my first response was all it needed
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Unread 07-15-2010, 07:50 PM   #4
Obnoxious1
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1981 CJ5 
 
Join Date: Jun 2010
Location: West Tennessee
Posts: 87
Quote:
Originally Posted by jeepgirl_90 View Post
any ideas as to why it's knocking or how I can get the noise to go away ?
Greetings! & Welcome to Jeep Forums!
Your going to have to give us a lot more to go on as far as a knocking sound.
Try to answer the following:

Dull thud knock or sharp loud metallic knock?
Can you tell what area of the vehicle it is coming from? (front, back, bottom?)
Does the Jeep run?
If yes, How well is it running? good, poor, like crap?
Does the knock get louder or faster if you rev the engine?
Does the knock only happen when your moving? ( or in gear )
If drivable, does the Jeep ride really rough? does it bounce? Pull hard to one side? steering feels loose? Does it shift gears ok? jerks when changing gears?
Are there any puddles under the Jeep after you park it?

Answer as many of those questions as you can in a reply & one of the many knowledgeable men & women on these forums will be happy to help diagnose your Jeeps problem.

Good luck!
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Unread 07-17-2010, 07:53 AM   #5
jeepgirl_90
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1990 FSJ Cherokee 
 
Join Date: Jul 2010
Location: PA
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Okay it is a 1990 Cherokee Laredo. 4.0 engine. I just got it a few months ago, It has a slight ticking noise that you hear well it is running. It was recently making another noise as well due to a wore out crank pully which I replaced. I just want to have an idea as to what the ticking may be. Maybe the rod bearings need replaced or how I can check for lifters that may be shot or stuck?
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Unread 07-17-2010, 11:05 AM   #6
Diamond-x
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1991 XJ Cherokee 
 
Join Date: Aug 2008
Location: Socal
Posts: 1,188
The 4 liter engine is noisy. Be sure you are running the proper oil level. A backyard trick is to take a short length of pipe, maybe pvc, and cup it to your ear. Then put the other end near the valve cover or near the lower block to see if you can isolate the location of the sound.
A tick is usually a valve and is common.
A bad rod bearing is very loud knock which gets progressively louder.
It will also produce metal bits in the oil.
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Unread 07-21-2010, 02:15 PM   #7
Silvestris
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1998 TJ Wrangler 
 
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Location: Crown Point, Indiana
Posts: 207
A light tick is usually your valvetrain, which is normal for an older car, it should be fine. My 93 Lumina had a valvetrain tick to it too, you really shouldn't hear it much if at all with the hood down. If it's louder than that it might be something more serious like a rod hitting, but with a rod you won't have much if any oil pressure and no power. My Lumina had that too. What it also could be is detonation/pre-ignition. It would sound more like a diesel engine and can hurt your engine pretty bad along with a rough idle. This can be easily fixed by using a higher octane fuel or an octane booster. A lower temperature thermostat would probably fix it too.
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Unread 07-21-2010, 02:30 PM   #8
BulldogTJ98
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1998 TJ Wrangler 
 
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Location: Olympia, WA
Posts: 620
Rods make noise in all 4.0Ls. they just do. Not a bad knock. just a low knock at idle. And the topend tick is probably a crack in the dang exhaust manifold. They're notorious for cracking.
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