Mechanics

85 CADDY ELDORADO-DRIVE NOISE PROBLEM

1985 Cadillac El Dorado

88,000 miles, HT4100, 325 4-speed transmission. There is a slow knocking/rapping sound when accelerating above 20 MPH, whether the car is cold or hot, and the rapping gradually gets louder as speed increases. At 35+ MPH the knocks increase to an extremely loud groan, all the way up to overdrive speeds. The noise stops when I let off the throttle and coast, and the slower knocking sound returns and continues as I coast to a stop. Whenever I shift into neutral while coasting all the noise goes away. When I rev the engine in neutral there is no noise either (not an engine problem). The transmission shifts tightly and smoothly and there are no slips. There is no vibration or shimmy. The front wheels when turned by hand off the ground do not wobble or make noise (not a wheel bearing problem). Even the differential is full, although with old fluid. The local mechanic says it's the whole transmission and I don't believe him. Could the differential and/or output shaft bearings be to blame? Thanks much, Greg
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85feb
June 2, 2007.



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