Engine drone at 2000 rpm **Fixed sound

slasher · **Posted:** Wed Apr 10, 2013 12:44 pm

Firstly I apologise for the quality, quite loud and clear on iphone but very low on PC. Listen for the 'woah woah woah' noise.

This is stopped in park but it is exactly the same when driving at any speed with the revs at 2000 rpm. I can't hear it with the bonnet (hood) open so dont know where to start looking.

Any ideas, clues, tips or anything else that might pinpoint it.

Thanks in advance.

https://soundcloud.com/slasherxxi/2000-rpm-2

papaindigo · **Posted:** Wed Apr 10, 2013 2:13 pm

Cannot listen, appears to require a Yahoo account.

naturist · **Posted:** Wed Apr 10, 2013 2:42 pm

I have a Yahoo account, and I can't listen to it either.

ech0sh4y · **Posted:** Wed Apr 10, 2013 3:57 pm

The link worked for me! I haven't heard that before. I'm going to go see if mine does that. I wouldn't even know where to begin on that. Something in the accessory drive system I would think is making a slight off pitch, harmonic sound.

papaindigo · **Posted:** Wed Apr 10, 2013 4:04 pm

Works now. Sound is very rhythmic; starts at ca. 10 second and runs until rpms drop then repeats at ca. 37 seconds as rpms pick back up. Thoughts and questions:
1. does it only do this when in motion or does it do it at the same rpms when not moving?
2. if only in motion - look at drive train - CV joints, drive shaft "U" joints, wheel bearings, separated tire, etc.
3. if only when not moving - look to serpentine belt idlers, tensioner, alternator pulley
4. if only in motion does sound change if taken out of gear and/or brakes applied or vehicle direction is changed?
5. does rhythm change as rpms rise above 2,000 and/or speed over ground changes?

slasher · **Posted:** Thu Apr 11, 2013 2:35 am

Either moving at any speed over any surface or stopped, exactly the same sound at the same volume, though sometimes not always, there is a metallic rattle just before it starts (about 1800 rpm) that I thought may be the alt pulley or a loose mount but alt is sound and engine mounts not sloppy or loose. I can't replicate the metallic sound at any rpm when stopped if that helps.

Starts to kick in around 1800 rpm and is gone over 2200 rpm which annoyingly where the engine always is apart from stopping and starting, so around town its noticeable on and off but on a run at 70mph its really noticeable.

Srytrucker · **Posted:** Thu Apr 11, 2013 3:03 am

So what was the cause and solution....please enlighten ....thanks.

skates04 · **Posted:** Thu Apr 11, 2013 5:48 am

Srytrucker wrote:

So what was the cause and solution....please enlighten ....thanks.

I think he just ment the sound clip that was not working was fixed, not the Jeep :mrgreen:

Auberon · **Posted:** Sun Apr 14, 2013 12:33 am

If it helps the chaps picture what is happening:
Averaging the sound map out and you would get a series of peaks and troughs in the 2000 rpm that kind of sounds like a rhythmic woo woo woo woo.

Suggestion:
Check under the aluminium heat shield at the exhaust manifold / turbo intersect.
To explain:
Note:
I could not here the metallic sound that Slasher describes.
I seem to remember on odd occasions when this happened a metallic rattle.

How to describe??????
I have heard a very similar tonal note.
After a quick check underneath, it lead me to start under the heat shield.
Its like the exhaust has a critical pitch / pulsing of gases that sets up a resonance somewhere in the system.

I used to hear it on my KJ when the rear exhaust to EGR tube was in place.
My research revealed yet another change-over of part in the production run whereby they used a different EGR connector tube (between the exhaust manifold tail and the EGR body- rear gas entry), It runs around the rear of the block. Mine part was a "2007 only designation" available only from CJD stealers for AUD600.
Consequently, I haven't replaced it (long story) - will TIG weld a new one with mods.
The old tube end that goes under the V clamp had radial hair cracks all around its circumference which leads me to believe it was the bad note.
The only thing I can think of to cause this type of destruction is resonance.

I believe that tube was of a build that would resonate with the exhaust note. The cracks occurred between the tubing and the supported portion under the V clamp.
It also had a longer straight portion than the earlier ones which was poorly self-supporting.
When it was removed the note went away.

If it helps - mine is an export model and in the September 2006 production run.
I do hope that isn't too confusing.

slasher · **Posted:** Sun Apr 14, 2013 6:15 am

Thank you Auberon, so in a nutshell, I (possibly) just need a new EGR pipe ie (stolen off that auction site) one of these?

Or have I totally misunderstood your post and there is another pipe?

Thanks again

Auberon · **Posted:** Sun Apr 14, 2013 9:58 pm

Slasher you did indeed understand my post.
That shape or similar - that looks suspiciously like a front pipe.
I suspect you may need the rear.
Good luck.

slasher · **Posted:** Mon Apr 15, 2013 12:25 pm

Thanks again

Is this the correct part number 05170765AA ??

Quick update, just been to check both ends of the pipe and they are spotless and solid, I'd assume there would be soot around any cracks?

kjjet · **Posted:** Mon Apr 15, 2013 6:20 pm

slasher wrote:

Thank you Auberon, so in a nutshell, I (possibly) just need a new EGR pipe ie (stolen off that auction site) one of these?

Or have I totally misunderstood your post and there is another pipe?

Thanks again

That's the EGR pipe that's cut to one inch long, welded shut and reinstalled on my CRD. Stopped all EGR.

Auberon · **Posted:** Tue Apr 16, 2013 10:30 am

Yes Slasher. That is the part number.
For pre-Sept 2006 or whenever the new shape was introduced to the production run - remembering the shape changed in 2006. The later part had less of a forgiving return on it. That support shown in the microfiche & the picture you provided was also absent.

Must add that mine is now of kjjet style in that I am blanked off with a Welch plug at the exhaust manifold tail - I ran down in outside diameter and shortened it up in the lathe then secured with the V band clamp. No EGR here either.

Re Soot: wasn't apparent until the break away of the pipe from the cup so fine were the fractures. Then after failure on a single trip boost was non-existent with no spool-up of note. Can you check with mechanics stetho around the V band clamp end?

From my reading a few have failed here.

Engine drone at 2000 rpm **Fixed sound

Who is online