How do you diagnose a bad differential or transaxle. What do you look for or hear for to locate it as a problem. And also, is it true that a bad wheel bearing makes a really loud noise? All right, lets see what you all think. TIA everyone

 

The way I found my front diff was bad was a very small leak of oil taht ended up dispersed under the bumper...discovered while I was getting PPS9s installed. Completely covered and replaced under warranty.

 

Depending on where the wheel bearing is it'll either sound like bodies bouncing in your trunk (refer to a front engine car, mind you! ) Or it will sound like the marble rolling smoothly around the inside surface of a coffie can. Also, depends on the severity, could be loud, or not so.

-the (automotive student) kid

 

wross996tt, yours is 4wd correct? thats why a problem is possible in the front diff?. mine is C2. one mechanic heard with stethoscope and said it was coming from differential. another mechanic said sounded like wheel bearing. The noise started after this incident:
I turned right and misjudged the curb and whacked the right rear rim pretty good. (took a chunk of rim off actually) (I laugh about it now but I was in tears at that moment) I still run the 265/35/18 tires where the rim sticks out more than the tire. I am more inclined to believe that it is a bad wheel bearing, especially cause it is cheaper to fix than diff. I tested with the car off the ground and the engine/tires running (tested up to 45 mph) no noise from the tires at all.
are bad diffs are common thing with 99 c2's?
Thanx

 

I would think that testing a wheel bearing with the wheels elevated probably isn't the best way....unless you want to see if there is play. There is no weight on the bearing and may not make noise even if it is worn. Try driving it and see if the noise goes away/worsens if you turn right vs. left. This will load the bearing (inner vs. outer surfaces)

 

My left front bearing has been replaced. In my case, there was a faint growl that changed tone with speed. Took the tech guy for a ride, and he thought it may be tires. The tires checked out OK, so he placed the car on a lift, then ran the car with all four wheels spinning, like your's did. Localized the noise to the left front wheel with a stethoscope that looked like a directional mike stuck to his ears. If your guy with the stethoscope said the noise is coming from the diff, I'm afraid that's where your problem is.