Good Morning,

I have a 1997 Mercedes Benz C230 with over 240k miles on it. Recently, while driving my car, I noticed a weird humming noise, from what I thought was possibly the transmission. The noise went away for a few drives, then one day, something sounded like it fell from it's place in the Drivetrain. I took my car home with a extremely loud humming noise, which now I think I've located to the Differential. Upon finally getting my car home, it felt like the wheels locked up and would no longer move freely. Now that I've had my car parked, I'm having issues with getting the car out of park, the Shifter is loose feeling and won't engage into any gears. I lifted up the car and have drained the transmission oil pan to see if there was any metal there, none found, except for some very dirty oil. My question is to you all, is there any way to full diagnose this possible Differential failure, without having any damage to the rest of the Drivetrain? This is my first time dealing with a Mercedes model, so the repairs are new to me. Also, is there a tool kit for removing the special bolts attached to the axles? They are a new type of bolt, that I've not seen before.

Thanks in advance for any guidance you all can give!

Jamison

P.S. I purchased Flex Drive joints because I thought those may be the problem. But I fear it's much worse.

P.P.S. Pictures of the Drivetrain can be available upon request!

Working on this car isn't any different than any other rear drive car except is has an independent rear axle. ( same axle shaft setup as a front drive car for the most part )

If the axle to differential bolts have a hole in them, they are XZN / Triple square .

If the bolts have a hear like a regular bolt but look splined, that is an inverse Torx. For the most part a regular socket / box wrench can be used, try a few sizes.

Does the noise sound like a screw driver being dragged across a fine tooth gear as it is spinning? Sort of an even fast tempo ZZZZZ sound.

These transmissions have a bushing between the input and output shafts, this wears and allows a needle bearing thrust washer to come apart and the metal parts get jammed in the planetary gears. These needles are about 1/8" dia x 1/4 " long.

When you say the shifter is loose feeling, is it looser that before the problem? There is a pinch bolt inside the trans that holds the lever to the internal linkage that might have come loose. This might cause the parking mechanism to jam.

With both rear wheels elevated and parking brake off, can you turn a wheel? Can you turn the driveshaft?

Don't randomly buy parts, diagnose first.

Thank you for your response! After looking over the car, I've noticed that there are different bolt types, compared Volvo and BMW. I wanted to make sure that I have the right sets to help make this repair job easier.

You mentioned this bushing between the input and output shaft, if it falls apart, can it lock up the transmission, making it very difficult for the car to move forward or backwards? After further testing, I've come to realize that the differential just needs fluid and no repairs are necessary for it.

This bushing, however, is that a simple fix? Or will I need to drop the transmission to replace it? When the car started having issues, I would have to say that the fast tempo Zzzzz sound was made, like a very heavy rubbing noise coming from directly underneath of my floorboards.

The little rubber bushing in the shifter has come out, so I am replacing that along with the repairs necessary to get me back on the road. I'm trying to use what knowledge and background I do have with cars, to make this job less costly.

Thanks again for any advice you can give!

J