Can't get rid of this hum - PeachParts Mercedes-Benz Forum

79Mercy · #1 09-14-2009, 06:33 PM

I have been trying to attack a very annoying hum coming from the fron passenger side wheel on the 76 300D. I have replaced the draglink, tie rods, and the wheel bearings(passenger side), swapped the tires from the 280CE, nothing has stopped the noise. I was only able to replace the inner bearing race, i couldn't get the out race out, there just isn't much metal to beat on. The hum is worse on turns, and will almost go away when I the car is bouncing up and down like on a road with high and low spots. It seems to be worse on right turns(curves in the road, not like 90 degree turns).

I have no idea what it could be, does anyone has any suggestions. Thanks

fruitcakesa · #2 09-14-2009, 06:47 PM

While I can't help you with your hum, I can commiserate with you over the concern and annoyance that a difficult to diagnose noise/vibe can produce.
I am living with a driveline hum/vibe that I suspect is a worn diff. but have yet to find the problem.
I figure to keep driving it until winter, at which time I will garage it and take it apart, or until it gets noticeably worse or catastophically fails.
Keep the faith since the answer is in there and you'll tease it out eventually.

79Mercy · #3 09-14-2009, 06:52 PM

Fruitcakesa, have you checked the center carrier bearing for play? Thats not a fun task to complete.

Thanks

Sev · #4 09-15-2009, 02:37 AM

Quote:

Originally Posted by 79Mercy

Fruitcakesa, have you checked the center carrier bearing for play? Thats not a fun task to complete.

Thanks

usually when this goes bad, there is noticeable vibration (rather than just a humming sount) at low speeds, particularly from 15-25mph

ImBroke · #5 09-15-2009, 05:58 AM

If it gets worse turning right, I'd say driver side wheel bearing. More of a load gets put on, and the noise increases. Going over a rise and drop in the road decreases the load, and the noise seems to go away. I'm sort of concerned that you couldn't get the race out, perhaps it is worn out, and the new bearing is sloppy in there.

fruitcakesa · #6 09-15-2009, 07:34 AM

Quote:

Originally Posted by 79Mercy

Fruitcakesa, have you checked the center carrier bearing for play? Thats not a fun task to complete.

Thanks

Not to hijack this thread but it is a new center carrier and bearing . The vibe starts being noticeable at 35 and peaks at about 50

79Mercy · #7 09-15-2009, 08:23 AM

The hum seems to be coming from the passenger side wheel.

When turning right the hum is so bad I can feel it in the floor.

The outer race is visually ok, and there is no play in it.

Maybe the sound is coming from the drivers side front wheel, i'll replace those bearings and races and see what happens.

MattBelliveau · #8 09-15-2009, 08:59 AM

Try swapping the front wheels left and right to see if the sound follows. Just to rule out tire noise...

Necrosavant · #9 09-15-2009, 09:04 AM

i was dealing with that in my CD when i had it ended up being my front wheel bearings, i also did not replace the inner race

winmutt · #10 09-15-2009, 09:19 AM

Replace the bearings properly.

Necrosavant · #11 09-15-2009, 09:42 AM

Quote:

Originally Posted by winmutt

Replace the bearings properly.

my excuse, though not a very good one, i had the car sold already..and i didnt have anything to pull the race out with..witch raises the question anyone got a trick to getting the race out? it also still to this day quiet by just replacing the bearing

rrgrassi · #12 09-15-2009, 11:10 AM

The races pound out with a big ole hammer and a drift punch. I remove the outer race first and then the inner one.

lutzTD · #13 09-15-2009, 11:11 AM

if you left in an old race, then most likely the issue is the bearings. Did you tighten the bearings by feel or did you use a dial indicator? Did you actually try removing the race and fail or did you not try at all. could be a high spot in the race caused by hitting or skewing it slightly.

TheDon · #14 09-15-2009, 11:12 AM

I agree.. I had to replace a race with on hand used parts once and It gave a bad hum until I replaced the passenger side bearings properly as a whole set.

dry ice is useful when removing races.

DeliveryValve · #15 09-15-2009, 11:58 AM

I agree it is the bearing. Always replace the races with new bearings.

I suggest you get another set of new bearings if you used the previous new set with the old races.

I like using sockets... That is if you can find one that fits...

http://www.peachparts.com/shopforum/attachments/diesel-discussion/72344d1253030205-cant-get-rid-hum-outerraceremoval3.jpg

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