300D Wheel Noise - PeachParts Mercedes-Benz Forum

tobybul · #1 08-06-2006, 07:24 AM

1985 300D
I notice a low pitch sound I know comes from the front wheels. Its very hard to describe. I would almost say its similar to brake pulsation sound - not feel. Slower when going slow, faster as I go fast and disappears. But more pronounced when I brake at slow speed. Normally, if its wheel bearings, I expect it to be there all the time with a humming sound - easy to detect especially when you turn your wheels left and right as you are moving.

But its not that kind of sound.

The brakes work very well but as I mentioned, that sound is more pronounced when braking.

Can't figure it out.

t walgamuth · #2 08-06-2006, 10:08 AM

has the car sat for a while?

if there is some rust on the calipers i might imagine it could do this.

tom w

meltedpanda · #3 08-07-2006, 11:12 AM

a had a very strange and similar sound on my 300Sd, turned out to be the bearings, see this thread

84 300 SD Front End Noise

janko · #4 08-07-2006, 11:42 AM

i had a very strange sound in my 240d whenever i turned the steering wheel to the right. re-packed wheel bearings on advice provided here. noise stayed. replaced engine mounts and the noise ceased. my experience.

tobybul · #5 08-07-2006, 11:27 PM

Quote:

Originally Posted by janko

i had a very strange sound in my 240d whenever i turned the steering wheel to the right. re-packed wheel bearings on advice provided here. noise stayed. replaced engine mounts and the noise ceased. my experience.

Wow! Thats a different take....
I did notice that this rumble is becoming more of howling sound and is loudest at about 40mph. It also seems to be coming more from the right side. I did put in a set of Pirelli P3000 today. The sound is the same with the new tires. I had some old Michelins which apparently has been on since 1997. The side walls were cracked, fatigued.

I plan to jack it up tomorrow and spin the wheels if I can detect any roughness. The funny thing is all the bearings were repacked in 04 by a local shop.

How difficult is it to change the bearings?

kmaysob · #6 08-08-2006, 12:36 AM

Quote:

Originally Posted by tobybul

Wow! Thats a different take....
I did notice that this rumble is becoming more of howling sound and is loudest at about 40mph. It also seems to be coming more from the right side. I did put in a set of Pirelli P3000 today. The sound is the same with the new tires. I had some old Michelins which apparently has been on since 1997. The side walls were cracked, fatigued.

I plan to jack it up tomorrow and spin the wheels if I can detect any roughness. The funny thing is all the bearings were repacked in 04 by a local shop.

How difficult is it to change the bearings?

the bearings are very easy to replace. i seriously doubt you need bearings unless they were improperly packed or too low a temp grease was used. should you decide to replace bearings make sure you buy seals.

meltedpanda · #7 08-08-2006, 01:15 PM

I still say bearings, easy to do, read up on how to pack and set load. I suspect your mechanic put too much load on the bearing and it failed

tobybul · #8 08-09-2006, 11:22 AM

Typically, bearing problems can be detected by turning wheel left to right while vehicle is moving about 30-40 mph. You could hear a distict change in the sound. This was the case on my Taurus that had 170k.

But I do not observe this on the 300D. I can't see the connection of this noise to the engine mounts. Is there a way to tell if the mount is bad?

With the 300D, its stars off as a low rumble from 25 to 40 mph. Then as you go faster, it changes to a low howl at about 50-60 mph. The car has 110k on it.

I just got it this summer and its very good overall for an '85. My understanding is that the car may have sat in the garage of the orig owner for some time. The fella I got it from who bought it from the orig owner had it for 2 yrs. One of the first things he had done is brake work: replace rotors, calipers, and repack front bearings.

I should ask him why he had it done.

The sounds kinda progressed over the 3 months we have had it. Not sure if this has any relation to it but up this week, the car has had older, unbalanced and oversized tires (205x75-14). The car vibrated due to unbalanced tires when cruising (60 mph on up). I don't know how long this had been going on. I am wondering if this vibration affected other components such as engine mounts and bearings. For sure, it increased the wearing of steering components.

But, since I replaced them this week, balanced and everythig, its much smoother at no vibration at high speeds. But the sound is still there.

meltedpanda · #9 08-09-2006, 01:24 PM

I still say bearings

On the mounts, look to see if they are collapsed, with engine running at idle observe rock, it should be dampened, also with engine off pull briskly form side to side see if you get clunk or easy movement. Worn mounts will be obvious

tobybul · #10 08-21-2006, 08:59 PM

Quote:

Originally Posted by meltedpanda

I still say bearings

On the mounts, look to see if they are collapsed, with engine running at idle observe rock, it should be dampened, also with engine off pull briskly form side to side see if you get clunk or easy movement. Worn mounts will be obvious

Am still a bit at a loss about the road noise I hear. It sounds more like a low rrrrrrrrrrrrrrrrrr and at times rrrrrrrr rrrrrrrr rrrrrrrrr at speeds up to 40mph and turns into a hummmm at higher speeds.

It really doesnt change pitch when I turn left to right. And its not the differential because I out it on neutral while cruising but sound still same.

I thought at first it was coming from the right front tire area but can't really say anymore. Any thoughts?

meltedpanda · #11 08-22-2006, 08:44 AM

Have you checked your flex discs?

however

I still say bearings

tobybul · #12 08-22-2006, 12:30 PM

Quote:

Originally Posted by meltedpanda

Have you checked your flex discs?

however

I still say bearings

What are flex discs??

meltedpanda · #13 08-22-2006, 12:34 PM

they take the place of differential joints on MB's both ends of drive shaft
typically they squeel, but I suppose they could produce other sounds.
Look for significant cracks around the flex plate where the bolts mount

tobybul · #14 08-22-2006, 06:22 PM

Spoke with my local MB Dealer svc mgr buddy about this. He said flex discs hardly go bad and thinks most likely its a wheel bearing.

I am hesitating to do this partly b/c I did open up one wheel other day up to remving the bearing cap. Spun the rotor and didnt really feel there was anything unusual. The red grease looked intact, etc. I realize this is not very scientific but I felt bad about messing up all that nicely packed grease. So I just put the cover back and here I am.

Looks like I really should get in there and do the work as planned.