Weird Noise above 40 mph - PeachParts Mercedes-Benz Forum

#1 03-19-2002, 10:06 AM

Driving to work this am, halfway through 50 mile drive, weird noise started. Kind of a high speed whine, pretty loud. 85 3002s (212,000) handled as always - just fine.

Gauges all OK. Pulled off and checked belts, undercar etc. Could see nothing. Car now at garage across from office but he has little experience with diesel.

Any thoughts what this could possibly be?

ATLD · #2 03-19-2002, 10:37 AM

Does the sound depend on veicle speed or engine speed (after you acquired the problem)? If the sound happens at slow speeds with higher rev, then the problem is engine related. If the problem occurs only at very high vehicle speeds, then the problem is either drivetrain, suspension, or aerodynamics related. I would personally suspect the transmission, if the noise is continuous at those speeds (as the rest of the drivetrain would make an intermittent noise; say at every wheel or driveshaft revolution).

First, before you start taking things apart, check the simple things: like trans fluid level, engine oil level etc. Also make certain that there is nothing that you drove onto that is touching moving drivetrain parts (bag, stick, leaf) as these could make loud noises at high speeds.

Good luck...

Let us know a little more when you find out a bit more.

ATLD

#3 03-19-2002, 11:48 AM

Thnaks for your thoughts. Seems a function of speed. Mechanic and I agree that the noise seems to come from the right side. He is going to put it up on the lift. He's thinking it might be a bearing.

I much prefer that it be the bearings rather than the drivetrain!

loubapache · #4 03-19-2002, 11:52 AM

Does the noise go away if you let up the gas pedal? If it is a wheel bearing noise, the noise will probably stay.

If it goes away, it could be a whine from the rear differential.

#5 03-19-2002, 11:59 AM

The noise remains constant until the speed drops down.

loubapache · #6 03-19-2002, 12:26 PM

So it is probably a bearing problem. There is a center support bearing too and that is in the middle of the two drive shafts.

#7 03-19-2002, 01:30 PM

Question...Is it safe to drive it home fifty miles or so...What could happen?

Capt Kirk · #8 03-19-2002, 05:40 PM

Make sure the lug nuts are all tight

If they are then it could be a bearing problem. We had that on my old VW (I've had a problem with EVERYTHING on that car it seems)

the wine would start out really quietly at about 5-10mph then start getting really loud at 20-25+.

ATLD · #9 03-20-2002, 12:49 AM

Should be safe to drive home: just check the obvious things first. Usually, a worn wheel bearing will make a clicking type noise every other wheel revolution, so I am left to believe that either you wheel bearings are completely shot (unlikely); metal-metal sounds, or it is something else. Considering that the problem onlu persists with speed and is not load dependent, I am forced to believe that it is either the trans, diff, or deiveshaft.

ATLD

Let us know how it goes...

Capt Kirk · #10 03-20-2002, 06:21 PM

clicking is a CV Joint, whirring is a bearing of sorts.

ATLD · #11 03-20-2002, 10:03 PM

capt kirk,
Please note for clarity, that if there is a clicking sound with EVERY-OTHER wheel revolution, as stated below, it represents a problem with that wheel bearing: being that the bearing rollers spin at 1/2 the speed of the wheel. This would most likely occur if a bearing race became deformed, usually due to an impact of some sort or another. Not common, but possible with Mercedes.

A CV joint fault would create a clicking sound with EACH wheel revolution.

I'm as interested as you are to find out the actual culprit.

ATLD

[Kirk]:

Scotty, I need more power!

[Scotty]:

Captain, I'm giving you all she's got! It seems to be only 88hp!

Capt Kirk · #12 03-20-2002, 10:24 PM

ahh, I didn't see the every other part, sorry about that.

I've never heard that a clicking noise is because of the wheel bearings, I've heard, and witnessed that a whirring noise was a bearing. But If you've seen a case where the bearings clicked then I guess your right as well.

#13 03-21-2002, 09:33 AM

Have driven this 300sd with 212K to/from work for two days now, about 250 miles total. Noise seens to have dropped back down to original levels. However listening intently, I still think it is a bearing problem because I hear a much slighter whirring.

Can't figure out why the noise has dropped back however.

leathermang · #14 03-21-2002, 09:47 AM

"the wine would start out really quietly at about 5-10mph then start getting really
loud at 20-25+." Capt Kirk

Capt Kirk,
Please note for clarity, Wine should not make any noise period, so if it gets loud get away from it quickly,,,, it is about to explode.... Greg

wheelguru · #15 03-21-2002, 10:26 AM

I can't resist.
if you can get the wine going 25+ you must be really thirsty.

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