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Trying to pinpoint a knock

H

hupo224

NAXJA Forum User
Location
Manchester, NJ
So it sounds like a diesel basically. Was not loud when I first picked up the jeep. It seems it is happening from me driving it more than the previous owner. After I did the first oil change (rotella sae 30) a few days ago it got pretty loud. It currently has rotella 15w40 and 1 quart of rislone.

I used a long screwdriver and it seems to be more loud towards the front of the engine.

Here is a video
http://www.youtube.com/watch?v=dVCMiiEs2mc


Inside the valve cover
auckS.jpg

SzaC9.jpg



Thank you
 
Gotta tell you that oil filler cap looks pretty nasty and also inside the valve cover. I think you may have an engine that has not had frequent oil changes.

How many miles on this engine? You may benefit from either frequent oil changes for a period of time to help clean the engine or a one time commercial oil flush product to help reduce the sludge. Or BOTH.

If after the above, it still has some engine noise, keep in mind that some engine noise with the 4.0, especially with miles, is not uncommon and can be thought of as more of a "characteristic" than a problem.
 
Last edited:
birchlakeXJ said:
Gotta tell you that oil filler cap looks pretty nasty.....

How many miles on this engine? You may benefit from either frequent oil changes or a commercial oil flush product to help reduce the sludge.

"Some" engine noise with the 4.0, especially with miles, is not uncommon and can be thought of as more of a "characteristic" than a problem.
Click to expand...

My last xj was a 98 with a bad exhaust leak and the motor was much more quiet. With 280k. When I picked the jeep up about 2 weeks ago the speedometer/odometer supposedly stopped working. It reads at 180k.
 
They say a picture is worth a thousand words.....those pictures tell the story of an engine that has not been maintained. Not to say you can't improve the situation, but it will be a PROCESS.
 
birchlakeXJ said:
They say a picture is worth a thousand words.....those pictures tell the story of an engine that has not been maintained. Not to say you can't improve the situation, but it will be a PROCESS.
Click to expand...

Yeah I'm just waiting for the motor to tell me the good news. I suppose I should save for an engine out of a rolled jeep.
 
My 95 ZJ sounds the same. I haven't had time to pinpoint it, but it sounds like its from my valve train. Goes away after about 1500 rpm

However yours sounds like its from the bottom end, from the video. Use a piece of hose to your ear to try to pinpoint the sound. Have you checked the flex plate bolts?
 
Last edited:
Talyn said:
My 95 ZJ sounds the same. I haven't had time to pinpoint it, but it sounds like its from my valve train. Goes away after about 1500 rpm

However yours sounds like its from the bottom end, from the video. Use a piece of hose to your eat to try to pinpoint the sound. Have you checked the flex plate bolts?
Click to expand...

I have not pulled the inspection cover and checked the flex plates. I most likely will. Mine seems to go away after about 1500 rpms too. She idles at a little less than 500.
 
Will do. Thank you. I'll post back with results.

Also took it to a shop where they used a stethoscope all over my motor. They said it is loudest in the rear of the engine on the bottom. Also noticed fresh oil coming from probably the rms. I'm glad I degreased the motor. Although my motor slightly hisses now since I did that. While at idle and driving.
 
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