4.0 making a knocking or tapping noise

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phoenix212

NAXJA Forum User

Location

Georgia

• Oct 6, 2010

• #1

Well, my beautiful, smooth running, well maintained under 150k 1996 4.0 engine has started making some noise. It started off as a ticking, I thought it was a lifter, then it got louder. It doesnt quite sound like a rod, and when I tested the cylinders by disconnecting the plug wires 1 cylinder at a time the sound persisted.

Its very loud, sounds like somebody is going to town with a ball peen hammer. Engine still runs fine though, smooth and no change in power. Oil is fine, and the oil has never been low.


Ideas?

 

ROBZ95Xj

NAXJA Forum User

Location

Keene NH

• Oct 6, 2010

• #2

could either be really bad piston slap or broken driveplat or loose driveplate bolts, pluu the inspection cover and check the driveplate and bolts

 

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cruiser54

NAXJA Forum User

Location

Prescott, Az

• Oct 6, 2010

• #3

Remove each torque converter bolt from the flexplate one by one. Clean it and apply LocTite before reinstalling and torqueing them. VERY COMMON PROBLEM.

 

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phoenix212

NAXJA Forum User

Location

Georgia

• Oct 6, 2010

• #4

cruiser54 said:

Remove each torque converter bolt from the flexplate one by one. Clean it and apply LocTite before reinstalling and torqueing them. VERY COMMON PROBLEM.

Click to expand...

Its a 5 speed, no torque converter unfortunately

 

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cruiser54

NAXJA Forum User

Location

Prescott, Az

• Oct 6, 2010

• #5

That shoots my theory all to hell, doesn't it?

 

ROBZ95Xj

NAXJA Forum User

Location

Keene NH

• Oct 6, 2010

• #6

either sticky lifter or bad piston slap then, my 98 had a pad piston slap issue when my mom orig bought it at 125k shortly after i got it the #6 piston let got at 150k

 

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phoenix212

NAXJA Forum User

Location

Georgia

• Oct 6, 2010

• #7

Alright, update.... There was what I thought was a slow oil drip from the pan gasket near the front belt so I tightened up the pan and thought nothing of it. Well...... Now I poked around and its quite wet under there, and I cleaned it up pretty good to see if ti was still leaking. I think its coolant, not oil. What is the significance of this?

 

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cruiser54

NAXJA Forum User

Location

Prescott, Az

• Oct 6, 2010

• #8

Water pump failing?

 

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Samson04

NAXJA Forum User

Location

Taylorsville, KY

• Oct 6, 2010

• #9

Check to see how much "play" is in the water pump pulley. I thought the same thing a about a week ago about my 98xj and it was the water pump. The bearings were shot. Worth a look anyway.