NHTSA Complaint #730234 — 2000 VOLVO S80

SEE ODI NUMBER 726533 FOR PREVIOUS REPORT. INTERMITTENT PROBLEM, NOW 4 OCCURRENCES: THRUMMING SOUND THAT GETS LOUDER AND TRANSITIONS INTO SIGNIFICANT RAPID VIBRATION OF ENTIRE CAR. CONDITIONS AT LATEST OCCURRENCE: DRY PAVEMENT, AIR CONDITIONER ON, DASH THERMOMETER READING 82F, STEADY 67MPH, TWO PEOPLE IN CAR. ADDITIONAL DATA: PUT TRANSMISSION IN NEUTRAL NO CHANGE; VARIED RPM (STILL IN NEUTRAL) NO CHANGE; TURNED OFF ENGINE NO CHANGE. RESTARTED ENGINE NO CHANGE; THEN STOPPED. VIBRATION DISAPPEARED AS SPEED DROPPED (BELIEVE ABOUT LOW 20S OR TEENS). RAN HANDS OVER WHEELS AND TIRES: APPEARED NORMAL WITH NO BUMPS OR EXCESSIVE HEAT. PROBLEM DID NOT REOCCUR WHEN I RESUMED DRIVING. COMMENTS: IVE HAD AN ONGOING COMPLAINT SINCE I BOUGHT THE CAR ABOUT A VIBRATION IN THE RANGE 60 TO 75MPH. THE VIBRATION FEELS LIKE A WHEEL BALANCE PROBLEM DESPITE SEVERAL ATTEMPTS AT RE-BALANCING. THE APPEARANCE OF THE THRUMMING SOUND AND ASSOCIATED SEVERE VIBRATION RESEMBLES A REINFORCING RESONANCE DEVELOPING FROM THE BASIC VIBRATION.