Mysterious Suspension Noise

donniefitz2

Well-known member
Sep 15, 2020
138
56
Scottsdale, AZ
fitzventure.com
For months I have been hearing a strange suspension noise under my D2 only when off roading. It happens most when the vehicle is being jostled side-to-side. The noise sounds like....a sea lion. It's a weird barking sound. The problem is, I can't tell where it's coming from. Sometimes it sounds like it's up front, other times in the rear.

Today I decided to strap a GoPro to the underside of the Disco at various positions to see what's going on under the truck when this noise occurs. I thought for sure it was in the rear, but after watching boring footage of the underside of my truck, the loudest occurrence of the noise is at this front angle.

All of my bushings look good. Shocks look good. New steering arms installed recently and the front sway bar is disconnected and secured. Nothing appears loose underneath. Yet I have this sea lion noise when off roading.

Here is a video clip of what it sounds like. You have to listen close to hear it over the engine, but it's definitely there. Does this noise sound familiar to anyone? I'm at a loss here.

 

Flyfish

Well-known member
Oct 29, 2004
1,355
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St. Louis
It sounds like a slight tire spin like you would hear going up a rock incline with very brief traction loss/tire spin. Try doing the same test drive with the cdl locked/low which should eliminate any spin.
 

donniefitz2

Well-known member
Sep 15, 2020
138
56
Scottsdale, AZ
fitzventure.com
You're right, it does sound like tire spin/tire slippage, but it definitely isn't. In this video it's in 4 low, 1st gear, CDL engaged on flatish loose dirt at about 5mph. The noise is coming from the underside....somewhere.
 

Flyfish

Well-known member
Oct 29, 2004
1,355
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50
St. Louis
It still sounds like a slight tire spin/skip. Could anything in the driveline getting bound up? You should put the truck on jackstands and see if all four wheels are spinning freely.
 

Blue

Well-known member
Mar 26, 2004
9,667
599
AZ
I'd guess bushing squeak or you may be right about a slight shifting of the spring. My 2004 had all sorts of squeaks, creaks, and groans with suspension movement. I routinely had all bushings inspected by Rov-N-Techs and they always reported that they were fine.
 

Blue

Well-known member
Mar 26, 2004
9,667
599
AZ
It sounds like a slight tire spin like you would hear going up a rock incline with very brief traction loss/tire spin. Try doing the same test drive with the cdl locked/low which should eliminate any spin.
He's on loose granitic gravel - tire drag or spin wouldn't chirp.
 

Flyfish

Well-known member
Oct 29, 2004
1,355
192
50
St. Louis
He's on loose granitic gravel - tire drag or spin wouldn't chirp.
If you listen closely, you can hear a slight gravel spin right before the passenger tire goes up a couple different bumps. And then chirps both times when he’s going over the top. May not be much gravel/dirt etc in those spots.

Just sharing my thoughts since the other suggestions didn’t pan out.
 

donniefitz2

Well-known member
Sep 15, 2020
138
56
Scottsdale, AZ
fitzventure.com
Thanks for all of the suggestions. I think I have narrowed it down to the front driver's side. I was finally able to reproduce the sound on a speed bump. I'm going to get under it and tighten everything. I suspect a spring moving around or maybe a loose radius arm bolt but haven't had time to check it out further.
 

p m

Administrator
Staff member
Apr 19, 2004
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La Jolla, CA
www.3rj.org
Thanks for all of the suggestions. I think I have narrowed it down to the front driver's side. I was finally able to reproduce the sound on a speed bump. I'm going to get under it and tighten everything. I suspect a spring moving around or maybe a loose radius arm bolt but haven't had time to check it out further.
You can also use the old trick of spraying bushings with WD-40 one at a time, and notice when the sound goes away.
 

donniefitz2

Well-known member
Sep 15, 2020
138
56
Scottsdale, AZ
fitzventure.com
Today, I went over the underside of this thing with a fine tooth comb. Nothing looks problematic with the suspension. With the help of my son running next to me while driving over some bumps off road, we narrowed the noise down to the driver side, around where the driver seat is.

I torqued the transfer case mounts (brand new) and they were tight. Then, it occurred to me that I haven't looked at the motor mounts. One appears to be cracked at the top, on the drivers side. The thing is, I don't have any bad vibrations and the engine isn't twisting on acceleration.

But, there is a chance that left side mount is cracked and the engine is moving around when the truck is jostled side-to-side making that strange noise. Does this sound plausible?
 

Blue

Well-known member
Mar 26, 2004
9,667
599
AZ
From my maintenance log on the 2004 you bought from me:

Actual MileageOdometer MileageDateNoteExpense
178,572167,2292/11/2020Rover Techs replace all 4 mounts (2 engine, 1 tcase, 1 trans). Rover Techs supplied estimate to replace leaking power steering pump & feed hose @ $875.
$608.27​
 
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Reactions: p m

donniefitz2

Well-known member
Sep 15, 2020
138
56
Scottsdale, AZ
fitzventure.com
It did cross my mind that I could just pull them from the parts truck, but I just bought new ones from Lucky8. Good to know those ones are good though.

Recently, my sway bar bolt punctured my A/C line near the wheel well. That's coming off your old truck. Every time I think maybe I'll sell it, I find something else I need from it. I'm going to swap the dashboard in a month or so. That truck just keeps on giving.
 

Blue

Well-known member
Mar 26, 2004
9,667
599
AZ
We were driving by the car dealerships up at Northsight and Frank Lloyd Wright a couple days ago and my youngest son Nicolas (4 years old) pointed at a dealership and asked me, "What's that place with all those cars?" I explained why we have car dealerships and he was amazed that cars can wear out and need to be replaced eventually. Then he asked, "Is that what happened to Bam Bam?" [Bam Bam was our name for my/your 2004] Then my other son Billy (7 years old) told him that the engine wore out but the rest of the truck was fine so we sold it to someone who would use all the good stuff. Nicolas asked why I didn't just fix the engine and we got mired down in the economics of putting a third engine in a 16 year old truck.