strange noise, cant locate

1982 300sd, 320 000 km

For my sanity, safety and financial well being, I NEED TO FIND THIS NOISE. It is getting louder and happening more often. Totally random if will or not make it.

Loud intermittent squealing noise and occasional grinding from the front of the car. Either center or off to the right of center. Squealing sounds like belt squeal but is not from the engine, does not go away or change when put in neutral. No change under different engine loads or rpm. No noises when stationary at any engine rpm. Must be moving. More likely to happen at higher speeds. This week started getting really bad and went from squealing to loud tinny rattle and suddenly stopped, came back a few more times and stopped again. On top of that, grinding noise turning corners at speed, sounds like tires scrubbing, worse turning right. No noise turning from wheel stop to stop. Is it related, I have no idea. car pulls to the right. Was aligned six months ago. Have not hit anything

New engine mounts, new wheel bearings, new tires, new tie rod ends, new track rod bushings, new brakes front and back, new belts and hoses.

Checked complete front end, found nothing, absolutely no play in anything or loose components, all mounts, bushings, lines, hoses, shields, guards, brackets, nut and bolts tight. Nothing hitting, rubbing or otherwise making contact.

Checked rear end, found sagging rear springs, blown out rear shocks, crusty diff mount and bad rear sway bar links, doubt any related to noise but on the to do list

Flex discs are good, center bearing rubber worn and on my list to do next

Removed engine fan and clutch, removed hood padding that was falling off anyway. removed fan shroud as well. Checked turbo for shaft play, air cleaner mounted tight

My right side fender is totally rotten behind the plastic body trim panel and vibrates at an idle. I have two new ones to install this spring. Again, doubt related

Can not think of anything else to check. I can no longer take this car any distance from home and avoid high speeds.

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1982 300sd, new project car to restore

It doesn't matter if you know what you're doing, as long as you look like you know what you're doing.

starter not disengaging completely? or somehow being spun up while driving?

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1981 NA 300D 310k miles

doubt the starter. Would change with engine rpm and would have no ring gear left.

Just had a thought, going to see if I can get a shop to let me run the car up on their drive clean rollers (like dyno rollers) to see if the noise is at all driveline related.

Are there ANY parts that are hard to check or next to impossible to diagnose? I pulled the fan clutch off when the tinny noise started. Have not heard that since

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1982 300sd, new project car to restore

It doesn't matter if you know what you're doing, as long as you look like you know what you're doing.

have you tried going down the road at 35-40mph, putting it into neutral, and turning the key to position 1 to shut the engine down? (not Off as it will lock the steering!) and coasting? That would show if it was driveline/non engine related as the engine would be stopped. I have done this before to troubleshoot weird noises, also helps noise checking on the diesels in general as its quite quiet when doing that.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

How far can you coast before trans damage? Same as towing. Have not tried this yet. Going to try in the morning. If it does not stop, and I cant get on a set of rollers, I will run it up on axle stands. Going to need to recreate this noise while stationary to find it.

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1982 300sd, new project car to restore

It doesn't matter if you know what you're doing, as long as you look like you know what you're doing.

Your data shows that it isn't engine related.

You also state that it is from the front of the vehicle.

Therefore, I do not see how placing it on stands is going to magically recreate the noise, when it's clearly coming from the wheels.

The error is likely due to a faulty wheel bearing or a maintenance induced failure when replacing the wheel bearings improperly.

I agree.

after the point where the noise appears, can you come to a stop and get out and feel the front wheels close as possible to the center? if the bearings are worn or improperly installed you should have noticeably warmer centers...

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

I wish it was wheel bearing. One if the first things I changed out because of the noise, found absolutely nothing wrong with the old ones, changed them anyway, SKF cups and cones. When the grinding started, I rechecked for excessive endplay (still set properly) and they rotated nicely. Have access to an on vehicle tire balancer for heavy trucks (spins up the wheels on chassis) going to spin up the front wheels and see what happens. Gave the bearings the ol' heat test too, all similar temp.

Placing it on stands and running it up would help show if it was from the trans or some strange harmonic showing up in the front, caused by the back? Just willing to try anything at this point. I went looking at a parts car for major component swaps if it comes to it.

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1982 300sd, new project car to restore

It doesn't matter if you know what you're doing, as long as you look like you know what you're doing.

OK, I am convinced you have done the right things with the wheel bearings. Now, I question whether the noise originates from the front of the vehicle or whether you simply hear it that way from the driver's seat.

Put the vehicle on jackstands with the rear wheels elevated and the front wheels blocked VERY WELL.

Have another person "drive" the vehicle at various speeds. Get yourself close to the driveshaft center bearing (do not go under the vehicle). See if you can determine if the center bearing is the culprit. This becomes far more likely if the driveshaft has never been out of the vehicle for service.

you should be able to coast for a mile or more if you had the vehicle driving up to speed...
trans damage from towing is on a cold trans. and it's OK to tow for MILES at up to 25mph that way.
I think if you were driving and the noise started, and you put it in Neutral and the noise continues, and you turn off the engine, and the noise STILL continues, at the very least it will be easier to hear where the noise is coming from!!

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Hope no one thinks i am dissmissing their suggestion, I really am checking these things or have checked them, sometimes twice or more. No one can find this noise. I am class A licenced truck and coach tech, car tech friends, can not find this. This will be a strange one when I do find it.

I have gone as far as zip ties around anything that moves to see if it was resonating while driving

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1982 300sd, new project car to restore

It doesn't matter if you know what you're doing, as long as you look like you know what you're doing.

Check the heat shields on the motor mounts. I had on that got bent on a engine install that I didn't notice. It was rubbing on the body and making a squealing belt sound. And only did it once in a while. I tightened the belts a few times before I found the rubbing heat shield. A quick bend of the metal and the sound was gone.

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I had a disasterous squealing on my 190d that I was convinced whas the a/c compressor. I drove it for weeks without the ac until I discovered it was actually the auxillary vacuum pump under the rear seat that was failed. It had a slow leak, and would recharge at random, causing a loud bushing failure to reveal itself. The point being that I jumped to a conclusion, and relocated the noise to suit. Your noise may not be engine or running gear related, especially given the long list of new parts.

Agreed. Now to get the noise to show itself while the car is stationary

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1982 300sd, new project car to restore

It doesn't matter if you know what you're doing, as long as you look like you know what you're doing.

Never reinstalled them. Until I find this noise, I am removing parts and not reinstalling them, heat shields, fan, shroud

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1982 300sd, new project car to restore

It doesn't matter if you know what you're doing, as long as you look like you know what you're doing.