I was driving my car home the other day and all of a sudden i heard some very loud noises from the rear. When i got the car home ( after driving through the noise) The grinding / clinging / banging / scratching noise is coming from the differential? Does this mean i need new gears or what? Just trying to figure out how much this is gonna cost or what to do about it! BTW its a 1991 Pontiac Firebird V6

Thanks

 

Could just be a bad bearing, I would pull the differential cover and inspect the bearings and ring gear and try to determine if it's an axle bearing or in the diff. Bearing replacement isn't to expensive if you can do it yourself.

 

I got the cover off... I can't see anything that looks wrong, when i spin the tires it all seems alright? All the teeth on the gears look good though...

 

check the spider gears in the carrier Ive blown alot of them.

 

Not sure really how to check them but they look alright?

 

Lift and jack stand the car, start it put it in gear and let it idle and listen for a gear or bearing problem. It won't hurt it with no gear oil for a short test. Also was there any metal pieces in the oil? Make sure your U-joints aren't bad.

 

i didn't see any metal pieces in the oil... But i have the rear on stands, is that good enough?

 

Just make sure it's safely on the stands on a solid surface and just idle it. And if possible don't get underneath the car with it running.

 

Alright i started it up and put it in gear... Everything looks good in the case... Could it be the U-Joint? I just hear a bad sound coming from there somewhere, and it seems worse in reverse. I did notice some fluid leaking where the u-joint and diff. case meet?

 

It could be a U-joint, The pinion seal is leaking. With the engine off and the tranny in neutral, go under the car at the U-joint and try to wobble the drive shaft, and or have a friend rotate the tire back and forth.

 

Yeah i just went out and it does seems to rock back and forth quite a bit when i rotate it by hand... seems pretty loose!?

 

Would you recommend taking it to a garage to fix the u-joints? or you think me (amateur) could handle it? I do have the Haynes manual which walks you through it... Or if i do take it to a garage u have an idea of what it would cost?

 

Make sure the rocking isn't just the normal play in the rear end. By movement i mean slight movement in the U-joint itself.

 

yeah i believe thats where its coming from

 

Well that 's good. As far as you diff. now you can be confident the gears are good and the rear end grease probably needed changing anyway. Now would be a good time to replace the leaky pinion seal also.

 

Alright, and how much do u think a garage would charge to change the joints?

 

Depending on the garage, $200-$300, You could do it yourself or get someone to help you for probably $50 for 2 U-joints or even a little less. It's not that hard, it just helps to know what your doing.

 

Alright well i think i might try it... And dont u need a special tool? And do i need to replace the diff cover gasket now that i took it off?

 

No special tools, and yes to the gasket ($5-$7) Get a repair manual if you don't have one already. Don't be afraid to ask someone for help, Good luck.

 

Someone said i should make sure the axel isn't spun/ twisted first? And is it possible that the ujoint would suddenly go out or whatever while i was driving... even though the driveshaft didnt actually hit the ground...

 

U joints arent too bad to replace if they are aftermarket ones. The original Gm U joint ( which u might still have) is not held in with snap rings, They are held in place with a hard plastic goo that does not come apart easily. You have to heat them up really hot and that goo snakes out of the holes in the yoke. It pops and cracks too. B carefull have fun.

 

Alright well my first problem is i took the retaining straps off the rear end u joint, and it doesn't seem to wanna come out still, do i have to hit it or something?

 

bump or pry it towards the front, then slide it out of the trans, being careful not to drop the front yoke and scratch it or get it dirty. By the way if your gears are ok , I'm sure you haven't spun an axle.

 

Alright and when i say the gears are okay i am saying that bc i dont see any excessive wear or broken teeth. And i guess i just wasn't prying hard enough of something....

 

Also it just suddenly started making noise and clunking... wouldn't bad u-joints make that a slow process? Unless they break which didnt happen...

 

U-joints very seldom if ever break, the only time I've seen them break is at the drag strip. They where out and can make a lot of racket sometimes, anywhere from a clunk to squeak to grinding sounds.

 

Alright sounds good, i'm gonna try to get the shaft out again later today. And i have all of those sounds coming from the rear! But its not a consistant sound it makes noise then will get quiet and keep changing...?

 

Alright well..... I replaced the U-Joint and that isn't the problem. When i put the car in gear you can kinda hear it scraping then when i hit the brakes it gets worse and is a deep grinding sound. Is it the bearings?

 

Well now from what your saying; Have you checked your brakes? This is getting to be kind of hard helping to diagnose a problem without actually hearing it. When you had the car up on jack stands and the car in neutral (engine off), while turning the tires, could you narrow it down to one side or the other, Do you have drum or disc brakes?

 

I dont hear it / notice any problem when i manually turn the tires. AND i didn't think this would matter but as soon as all this happened i noticed a brake fluid leak on my RR. What could be the problem there?

 

and there drum...

 

Again; do you have disc or drum brakes? I suppose it's possible that some part of the RR brake let go. Have you taken the wheel off and looked? I see you said drum. It's possible a spring or brake shoe broke. Can you hear it on that side?

 

No im pretty sure i hear it at the diff. But i did take that wheel off and look at the pad, i thought it all looked good but i do have brake fluid leaking down the inside of that tire

 

and the pads look good, / besides the fact they have fluid on them, and it deff sound more like a grinding sound

 

guess i gotta take a video and youtube it lol

 

did the torque arm come out of the trans mount????
ie:hitting the trans tunnel???

 

I took an unloaded a video of my car running so you guys can hear what im hearing.

http://www.youtube.com/watch?v=zIGVE9babGI

 

yeah thats gotta be brake related
take off your calipers/bridges/and rotors and do that again
or drums

 

From the sound on the video, sounds like on the driver's side, check inside the brake drum, then maybe the wheel bearing.

 

its not hitting your bump stop is it?

 

Not sure how to check if its hitting the bump stop? But i have a new video up of the drums / wheels being off... the pads are still on. And I also have quite a wobble at each end of the axle? I think some noise is coming from the diff bc of no oil?

http://www.youtube.com/watch?v=rQW4MuFXfwM

 

It's not as loud of a screeching noise anymore i dont think. But could that possible be in part becuase theirs not as much weight on a possible bad bearing? Because in that video it sounds like a bearing spinning w/o oil?

 

I hope your not running it too much with no oil. Can you move the axle up and down or side to side. And can you turn the axle by hand and feel or hear the grind? Also is your drums scraped up inside.

 

When i turn it by hand i dont hear it but i do feel a VERY slight bumpyness as i turn it. AND i just went out and it does move quite a bit up and down...prob like 1/64 - 1/32?

 

Very possible then it's a bad axle bearing. The drums are O-K then?

 

yeah they look good, and which one is the axle bearing?

 

The axle bearing is on the axle behind the hub, the axle needs to be pulled out of the differential. I assume you will need help to do this? Is there anyone you know that can help you. With the cover off and the grease drained and the drum off, your half way to removing the axle. But i would recommend finding someone with experience on removing the axle.

 

Alright and is the axle bearing different from the wheel bearing?

 

The same thing.

 

srrry this shouldnt be here