I have a 1985 300SD turbo diesel with 309k miles. I have just notice a clicking noise that is coming from the right front area. The clicking frequency increases with wheel speed, not related to engine RPM. It's like there's something sticking into the slots in the rim that makes a 30 clicks for every wheel rotation (I already checked, there isn't anything). Once above 40 - 50 mph the clicking is so fast that it isn't discernable anymore.

I first thought wheel bearings, but putting the bearing under lateral loads doesn't change the noise at all. I don't see anything that would be rubbing against the tire or rim under windload, plus since the clicking starts from a stop there's no windload to deflect anything yet. The noise seems to be forward and right of the transmission so I don't think it's driveshaft related. It could actually be comming from under the passenger dash-board/firewall area, but I don't know of anything inside the car that would be wheel speed related.

Any ideas?

Thanks.

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1985 Mercedes-Benz 300 SD 309k miles
2003 Mercury Marauder 300B Blue
2006 GMC 2500HD Crew Cab/8' Bed; 21.5' long
2002 Pontiac Bonneville SLE

Some new info; it appears this clicking goes away at higher ambient temperatues, makes noise at 70F, not at 90F.

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1985 Mercedes-Benz 300 SD 309k miles
2003 Mercury Marauder 300B Blue
2006 GMC 2500HD Crew Cab/8' Bed; 21.5' long
2002 Pontiac Bonneville SLE

Have you jacked up the car and spun that wheel by hand?

Mike

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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra