Loud Rythmic Drone - PeachParts Mercedes-Benz Forum

Tpawlik · #1 10-28-2010, 02:03 PM

I had a lot of noise coming from the rear end. I took it to George Gantner in Cleveland and he diagnosed it as a bad left rear wheel bearing, which he replaced. That changed the tune. Now between 70 and 75 mph I still have this really annoying droning sound when on the throttle. Passing or climbing a hill it really kicks in. It gets much quieter when I let off the throttle The sound starts to oscillate at 73 mph. Below 70 and above 75 all I hear is the engine which is at an acceptable noise level. I read some old posts about the same sound, but no one ever really solved the problem. One person switched the tires from front to rear and that helped. I will do that tonight.
I checked the trans mount, flex discs and the center support bearing everything looked OK. The subframe, diff. bushings, half shafts and rear shocks are new.
George did say I had a little pinion noise, but it is not the source of this wretched droning.

Biodiesel300TD · #2 10-28-2010, 02:08 PM

Vibrations can be really hard to track down. You might also make sure you tires are properly balanced. Something that looks good at rest might not be so good when you are traveling 70mph down the highway. An imbalance in the driveshaft could cause vibrations.

vstech · #3 10-28-2010, 02:10 PM

load changing noise is usually in a u-joint, or diff gears...

vstech · #4 10-28-2010, 02:11 PM

define "new" on the axles... are they by chance mcparts Chinese sub 80.00 new axles?
do you still have your original axles?
axles will indeed cause this noise, and the cheapo or poorly rebuilt axles are a prime candidate for the noise.

babymog · #5 10-28-2010, 02:14 PM

Reading your original post, ... are you married?

Sorry.

babymog · #6 10-28-2010, 02:24 PM

Check to see if the exhaust is touching the body isolators.

Tpawlik · #7 10-28-2010, 03:06 PM

John,
The new half shafts are Chinese. But, it was making this noise before I changed those. The new bearing only stopped that particular noise. I did keep the originals. Did I see that you are re-booting some half-shafts?

Jeff,
I was married, but not anymore.
I did check the exhaust sytem which I removed to drop the subframe. It is new and is not hitting anything.
I have done so much to this car and am very pleased with the performance and the way it drives, but this noise really sucks. It is however, a very effective speed control!

snookwhaler · #8 10-28-2010, 04:58 PM

Quote:

Originally Posted by Tpawlik

I had a lot of noise coming from the rear end. I took it to George Gantner in Cleveland and he diagnosed it as a bad left rear wheel bearing, which he replaced. That changed the tune. Now between 70 and 75 mph I still have this really annoying droning sound when on the throttle. Passing or climbing a hill it really kicks in. It gets much quieter when I let off the throttle The sound starts to oscillate at 73 mph. Below 70 and above 75 all I hear is the engine which is at an acceptable noise level. I read some old posts about the same sound, but no one ever really solved the problem. One person switched the tires from front to rear and that helped. I will do that tonight.
I checked the trans mount, flex discs and the center support bearing everything looked OK. The subframe, diff. bushings, half shafts and rear shocks are new.
George did say I had a little pinion noise, but it is not the source of this wretched droning.

Does your car have the Resonator installed or did someone remove it and straight pipe it (you said it's new). Mine was really quiet before I removed the Resonator. Now it "drones" at anything over 70MPH. Same as you describe above.

Also, check to see that none of the exhaust system is touching the body and that all the exhaust hangers/mounts are attached and intact. Be sure to check the one at the transmission.

winmutt · #9 10-28-2010, 06:24 PM

Quote:

Originally Posted by snookwhaler

Does your car have the Resonator installed or did someone remove it and straight pipe it (you said it's new). Mine was really quiet before I removed the Resonator. Now it "drones" at anything over 70MPH. Same as you describe above.

Also, check to see that none of the exhaust system is touching the body and that all the exhaust hangers/mounts are attached and intact. Be sure to check the one at the transmission.

I was going to say same here. Sure its not muffler?

Tpawlik · #10 10-28-2010, 06:31 PM

The exhaust system is from the dealer per the recall.
Funny thing about that hanger at the transmission. After I had checked the front flex disc and center support bearing I noticed the belly pan was cracked and the slot in it did not align with hanger arm. The hanger arm was attached on the wrong side of the mounts. I put it back where it belongs and patched the crack with figerglas cloth on the inside.

Tpawlik · #11 10-28-2010, 07:46 PM

I found the problem!!!!!! When I was driving home tonight I was working the throttle, listening and watching the tach and speedometer. When I stabbed the throttle I realized the noise got much louder before the speed or the rpm changed much. When I got home I searched the net for "excessive turbo noise". There was a guy that had a turbo on his gasser Jeep. He had a lift kit installed at a shop and his Jeep is now roaring and droning at 70 mph. Someone suggested that he had a leak somewhere in the plumbing from the air cleaner box to the turbo. Turned out, the shop removed some intake plumbing and did not properly reconnect the rubber elbow to the turbo.
So, I went out and checked mine. The elbow was connected but the clamp was so loose that I was easily able to slip the elbow of the turbo inlet.
When I first got this car and was changing all the fluids, I installed a new lower radiator hose and t-stat. I removed the rubber elbow from the air cleaner box and the turbo for better access to the hose clamps. I also cleaned a lot of oil and dirt from the elbow. But, I forgot to tighten the clamp at the turbo!!!
So, the rear wheel bearing cured some of the noise. Sealing up the intake side of the turbo solved the droning. I took it for a blast up the interstate tonight, it sounded so quiet I thought I was driving my soon to be returned leased 2009 Hyundai Sonata.
I hate it when it takes me so long to solve problems on this car, but I really like that the fix was free.
Thanks for everyone's help.

babymog · #12 10-28-2010, 08:55 PM

Where is Streetsboro?

vstech · #13 10-28-2010, 11:14 PM

Quote:

Originally Posted by Tpawlik

John,
The new half shafts are Chinese. But, it was making this noise before I changed those. The new bearing only stopped that particular noise. I did keep the originals. Did I see that you are re-booting some half-shafts?

Glad you found the noise! congratulations!

yes, I am indeed rebuilding UN-ripped original MB axles! if yours are not torn through, you can successfully reboot yours. or buy a set from me if yours are torn through! the chinese ones will fail soon. the MB ones will not.

Tpawlik · #14 10-29-2010, 07:46 AM

Jeff,
Streetsboro is a suburb of Cleveland.

John,
My original boots were not leaking, just badly aged. I was reading some of your earlier posts when you were contemplating rebooting axles. It appears to me that there will be lots of people who would pay to have this done correctly and not have to wrestle with boots, me included. When should I send mine to you and how much? Do you already have a Paypal account?
I'm not a lawyer but you should make it very clear to people that you are re-booting only and take no responsibility for the condition of the actual CVJ or any other hard parts.

vstech · #15 10-29-2010, 12:41 PM

thanks! I'll pm you on the details.

yeah totally clear! I will NOT reboot any torn axles, and I have no warranty on the axles themselves, but I do clean them well, and put in the desired lubricant. I've already pulled some that have screw clamps on the boots, and I just toss them into the recycle pile, as I only want uncontaminated OE axles to get rebooted by me, and I cut them and verify the oil is still in there, and not full of metal or anything! then clean out all old oil, and fill with what the buyer wants in there!
I also twist the ends, and check for any felt play. if I feel any movement, into the recycle pile it goes!
I mark the axles as they come out of the cars, and I'll sell them d&l sides, the buyer puts them on the side they want to. some have said reversing sides, prolongs the life of the axle. makes sense to me.