1982 300D turbo
I have developed a high pitched squeal when turning. I noticed it a couple of days ago, but had a chance in an empty parking lot today to do donuts for several minutes to assess it better. Turning wheel to right and idling a large donut produces a loud squeal that comes from front passenger side and sounds cyclical, and the sound stops immediately when brakes are applied. Same thing happens on drivers side when wheel is turned to left, but not nearly as loud as passenger side. Sound is not present when driving straight ahead. Any thoughts? Thanks, Alex.

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"Frau Blue Car" 1980 240D think Frau Bluker, cue the horses, formerly known as "China" from JimmyL
"Gunther" 1982 300D.....Turbo!! A/C!! Sunroof!!
"Fraulein" 1975 240D----Donated to NPR

Power steering belt. Thats my guess

yep.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I don't think it is belt- doesn't sound like a belt. It sounds like squealing brakes. It also stops immediately when pressure is applied to brakes. I cant make it happen just by turning steering wheel when at a stop, car has to be moving. Also, sound comes from passenger side when steering wheel is turned to the right, and comes from the drivers side when steering wheel is turned to the left. Sound is much louder from the passenger side. I really think it is the brakes, but can't imagine a scenario in which the brakes would create a squealing noise just by turning the steering wheel. Could it be a bearing that is loaded more heavily with a turn creating the squeal, which is then reduced enough to stop the squeal by applying the brakes?

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"Frau Blue Car" 1980 240D think Frau Bluker, cue the horses, formerly known as "China" from JimmyL
"Gunther" 1982 300D.....Turbo!! A/C!! Sunroof!!
"Fraulein" 1975 240D----Donated to NPR

my first thought was belt, until I read your description... sounds like a bad pad on one wheel, likely right front... I'd pull the calipers, and inspect.

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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!

Maybe power steering pulley hitting the upper oil cooler line, due to a collapsed engine mount.

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Sam

84 300SD 350K+ miles ( Blue Belle )

Check play in the wheel bearings. Too much play can cause the rotor to shift enough to contact a pad. The caliper pistons don't retract much when you release pressure. Indeed, the only thing that retracts them is slight rotation of their square O-ring seal (all calipers I know of). When the seals get old, or cylinders get corrosion, the pistons may not retract enough, termed "stuck caliper", but could simply be too much play in the hub. Jack up by frame until a front wheel hangs in air and try moving it (like turning does). It is just like checking & adjusting bearings in a bicycle wheel. If you do adjust the bearings, don't over-tighten or they will bind as they heat (big problems). Read the manual and back off appropriately from "finger-tight".