Synolimit

wifes 09 c300 AWD started making a noise in the front passenger area. the noise is now loud! and gets louder as you go faster. its a constant noise but not a grind or metal sound. i was 100% sure it was a wheel bearing as again its not a grind and its something spinning 360 degrees with no flat spots like a warped rotor would have. also at the rate its spinning its very fast! a wheel or rotor would spin slower since it has a larger diameter. this noise spins fast like a bearing or axle or something.

yesterday i pulled everything off and the bearing did feel "tight." i popped the old one out and it looked fine. well i bought a new one from the dealer and installed and it didnt feel any different in my hands. i put everything back together and went for a drive and everything is 100% the same!!

now im thinking a bearing in the front transfer case maybe?? i really dont know at this point and it sucks!! also after i installed everything i now have no ABS, traction control, and a check brake pad wear light. i did have the radio on when working on it so unplugging everything with the power on im sure it thinks all that stuff is broken. so i need to do a full master reset or something as its all plugged back in and working ok.

anyone???

Synolimit

Not one person?

Skyline45

Take it to the shop and have the Transfer Case checked. The AWD 7 speed is prone to failure if not serviced properly, and most MB dealerships skip the draining of the TC while it's in for maintenance. Even though it's in the WIS... I had to fight with my dealership for a few hours before they recognized that this is something that must be done.

Synolimit

I found it. It's the rear drive shaft that goes into a piece with a bearing attached to the transmission. I put the car up in the air, killed the abs module and drove it up to speed. Should be a cheap bearing but hell to fix!!

Skyline45

Damn, nice catch! Good luck man xD

Synolimit

O and the bearing was backwards. All the lights were on because the bearing only has one magnetic side and the ABS sensor wasn't picking it up. I had to take it off and flip the bearing.

Skyline45

Was it done from maintenance or any other factor? It couldn't of come from the factory like that I would think.

Synolimit

I'm lost?

Skyline45

I thought you said the barring had been put on backwards. Nvm lol

tekfoc

had the same or similar issue I already knew it was the transfer case and sure enough it was.
Mercedes dealer replaced planetary gears inside that most likely includes the 2 roller bearings.100% sure

tekfoc

this what it looks like.

Synolimit

Lol it was, my bad. One sides magnetic and the abs sensor reads that. That's why my lights were all one. I flipped it last night and all is good except the original problem I misdiagnosed and spent $98 on a bearing I didn't need to. Meow time to fix the bearing or clutch pack or whatever's in that back 4" peice the drive shaft goes into off the back of the tranny.

Synolimit

I'm sure now what the problem is and it's not the transfer case. I had the car up on stands with more stands placed under the car in case it fell, disabled the abs module and had my wife drive the car up to 40 or 50 mph with my nose a few inches from the back of the tranny and that case. It's 100% coming from inside that case. My toyota tech friend told me they have a similar item on their awd cars 2006+ and it has a bearing and magnetic clutch thing and the noise sounds similar. I just need to head to merc and see the microfiche and go from there.

tekfoc

the noise I was getting was in tight left or right turns .
a rumble and binding.
nothing straight ahead no noise.

Synolimit

Gotcha. Mines all straight noise. Faster you go the louder it gets! Sounds kinda cool but gets annoying.

Synolimit

Mines coming from the one section back and it's always there, straight or not. Here's what's inside.

vinnicatz

hi I am new to this forum but have the same exact problem/noise in the front passenger side. The faster I go the louder it gets regardless if I am driving straight or making a turn. My local mechanic had the car up on the lift today and did something to put all four wheels in drive. All the wheels were spinning simultaneously except for the front passenger side wheel. Is the problem in the transfer case and if so do you happen to know how much this type of repair would cost at the dealership? Thanks for any advice or info.

ksauto1

I see the case is in 2 sections, can you remove just the rear section or do I need to remove both sections in order to repair? I need to know asap as I have the customers car on the lift now, everything out of the way and getting ready to remove it. Thanks for your help!!