I have a noise coming from the rear of my car. Its a 1999 Crown Vic/Grand Marquis. I am currently out of state and in school with limited tools and resources so I was hoping to get some feedback before I just pulled the diff cover off and slid the axles out. I only have the one car, so if I do that, I need to fix it right then and there...

The rear end vibrates slightly if at all, but makes a continuous womp womp womp womp....that increases with speed. I have had shafts go bad before and they usually just hum. this sounds almost more like my drive-shaft is out of wack[cant isolate it to one side or the other alone =/.. I had new tires put on and got it aligned, calmed the noise a bit but not cured it.

I am pretty sure it is just one of the shafts, but again the noise is not continuous, [only happens at a particular spot on the wheel per one rotation [i hope that makes sense...]

thanks

 

Rotate the tires to see if noise moves with wheels. Possibly one of the wheels are bent.

 

wouldnt they have noticed if one of the wheels was bent when they installed the new tires today and balanced them? i just had it aligned too. And they did rotate them, Sounds the same as it did just not as apparent.

 

If your rear end is causing the noise your fixing to have a catastrophic failure. I would jack it up after I chocked it good and carefully pull the drive shaft. Check for play in the front yoke and the joints. Next with the shaft out check for excessive play at the pinion nut. In out up down etc. Get someone to roll it around in a quiet place and listen with your hands touching the housing. If it's a flat spot on a tire (crash stop) and or a bent wheel it wont make a sound. I took a Car to sears once and when I picked it up one of the wheels was little more than finger tight and almost ruined a wheel and did damage some studs. Good Luck. Sunfish

 

I changed teh fluid in the diff and it was terrible, practically sludge like it had never been changed. There was metal mush on the plug magnet but not much, so I am hoping its just the bearings or shafts getting chewed on. I need to open the diff up and see what exactly it is, I just do not have time...When I had it jacked up there was a good 1/4 or more [just estimating] of play in the rear wheels when I pulled on them, and visually you can see them moving quite a bit with the car running and in gear on stands... very noisy at both the wheels, so i am pretty sure its just the shafts or bearings. =[ I have to drive it until winter break, hopefully it lasts that long. If the gears are dead, they are going to die anyway, hopefully it is just the shafts.



I know it is not the tires, I literally just put new tires on it.