Still Chasing that Roaring Sound - PeachParts Mercedes-Benz Forum

Tpawlik · #1 11-18-2010, 07:33 AM

After replacing both front wheel bearings, the left rear wheel bearing, half shafts and oil in the diff. I might be getting closer. I checked the center support bearing. The rubber in the support was torn, the rubber boot that covers the splines was gone and when I removed the bearing, it was bone dry and filled with sand.

Haven't driven the car yet. I dropped one of the flex disc nuts and it did not hit the ground. I looked for it on the trans mount and the transmission for 30 minutes last night before I gave up. I'm gonna buy a new nut today.

If the new center support bearing doesn't make the car quieter that my brothers Ford F-350 PowerStroke, motor mounts are next.

Alastair · #2 11-18-2010, 08:20 AM

Certainly sounds like that bearing was toast!

Combined with a torn rubber-mount would defo transmit vibration to the cabin.

Personally, I would be surprised if it Wasnt the cause....

While you're under there give the flex-discs both ends a good inspection, these can sometimes give a vibration that varies with speed....

Tpawlik · #3 11-18-2010, 08:39 AM

I am really hoping that bearing was the cause of all the noise. Both flex discs look good, no cracks or deforming. I had an indy check them about a month ago and he said they were good.

Tpawlik · #4 11-22-2010, 06:45 PM

Well I changed the engine mounts. The whole car feels better. It is still loud when on the throttle, even at low speeds. Cruising below 2,500 rpm is really good. I have to listen to hear the engine. BUT, it is still howling/roaring up to 2,700 rpm. It changes pitch, at 2,400 to 2,500 rpm it gets that propeller or synchronized boat engine sound, either cruising or accelerating. At 2,800 or above it is much quieter, acceptably quiet, even when on the throttle. The only problem with that is, I'm doing almost 80 mph.
This problem is really annoying me.

vstech · #5 11-22-2010, 10:03 PM

how is the exhaust? many have bored out or bypassed the cat back there, look yours over for holes.

Tpawlik · #6 11-23-2010, 09:12 AM

Thanks John,
That's a good idea, but the entire exhaust system is new this year by the dealer as part of the Trap campaign. Overall the car is much quieter, but still annoying between 2,600 and 2,800 rpm or 67 to 74 mph. Maybe it's those chinese half shafts! I need to send you my originals for rebooting when I can stop buying other parts.

vstech · #7 11-23-2010, 09:51 AM

hmm. new is not always perfect. couldn't hurt to go over the pipes with a magnifying glass.

Tpawlik · #8 11-23-2010, 12:04 PM

I need to adjust it after doing the engine mounts. It is hitting somewhere. I will check it closely for holes or leaks.

Tpawlik · #9 11-24-2010, 12:07 PM

I saw a thread about the casting marks to align both halves of the driveshaft, so I checked mine. The marks were about 90 degrees off. I aligned the marks and the propeller/boat engine sound is gone. With that and the new center support bearing, but mostly the engine mounts, the car is much quieter at all speeds. Not sure if I screwed up the driveshaft alignment or someone else, but at least now I can hear the radio or have a conversation with someone while going down the Interstate.
Thanks to everyone who offered their suggestions and ideas.

Billybob · #10 11-24-2010, 12:22 PM

Quote:

Originally Posted by Tpawlik

Thanks John,
That's a good idea, but the entire exhaust system is new this year by the dealer as part of the Trap campaign. Overall the car is much quieter, but still annoying between 2,600 and 2,800 rpm or 67 to 74 mph. Maybe it's those chinese half shafts! I need to send you my originals for rebooting when I can stop buying other parts.

I recently posted regarding 124 axles, these can be rebooted by almost anyone, all you need is a pair of spring clip pliers and a CV Boot Strap Crimping Tool/Tightener that can be rented at Auto Zone. The inner CV comes off, allowing the outer boot to be replaced also. Good luck!