Banging noise after letting off of the gas

[JoeJoe]

Anyone know what the cause is of a loud banging noise after I accelerate then let off in the gas pedal? The bang sounds like it is coming from the rear of the car.

[JRL]

Anyone know what the cause is of a loud banging noise after I accelerate then let off in the gas pedal? The bang sounds like it is coming from the rear of the car.

That's not good, not good at all

It could be one of several things. The least expensive would be the rear brakes and/or the E-brake. They can rust and the shoe break off inside.
After that you're probably into the AWD and it could be really anything;
The differential, the viscous coupling, the bevel gear or the driveshaft, none are be cheap to repair/replace.
Sorry, but I can't be more help with just that statement

[JoeJoe]

I just took it for another test ride; when I let off of the accelerator I hear and feel a bang followed by a strange metal on metal grinding (shhhhh) sound. It is defiantly not the e brake, I had those all apart last night. Oh well! My first volvo will be my last. Should have done my research. I do plan on doing the work myself what ever needs to be done. Does any one know the typical costs of the expensive items "The differential, the viscous coupling, the bevel gear or the driveshaft".

[JRL]

More than you really want to spend.
As much again as the car is worth and perhaps more than that, depending on what broke
Driveshaft $1000 round numbers, one hour labor
Bevel gear $2300 round number and 5 hours labor
You don't even want to know the labor on the VC (you can buy that used).
But we're speculating, find out what's broken first
Helps to know the year and the MILEAGE

[JoeJoe]

It is a 98 with 115K miles. I got under the car last night; nothing seems unusual, their is a small amount of play forward and backward in the driveshaft. With the car in the air, I spun the wheels and it didnt make any grinding noises. I have a feeling that it is the VC. Im about to drive this thing off a cliff!

[JRL]

Joe Joe Dancer, your life is calling...!

Anyhow, the easiest (and first) thing you can do is remove the driveshaft and see if the noise remains. If it's gone, it's very simple, you need a new driveshaft.
If not we then go to plan B

When you bought the car were the tires even (tread wise) and are they now?

[JoeJoe]

Hi JRL thanks for all of your responses so far; however there is something I don't understand.

If I remove the driveshaft and the noise goes away, I am not sure how we can say that it is the driveshaft. Couldn't it also still be the VC, or rear end? It seems to me that the only thing I can prove by removing the DS, is that if it continues to make the noise then I would know that it is not the driveshaft. Please correct me if I am wrong. I want it to be as simple as you say.

I had my father take it for a ride last night; he thinks that the metal shhhhh sound is a rattle; maybe the disintegrated insides of the cat, or maybe a heat shield.

One other thing that I think that I noticed about the thump is that it as the car warms up it seems to not be as bad, or happen as often. Also it not only happens when I let off of the accelerator, It also sometimes happens when the tranny shifts.

Again, thanks for your help, all comments are appreciated.

When I got the car it had 4 new tires. Unfortunately cant tell what was on before.

[JRL]

Hi JRL thanks for all of your responses so far; however there is something I don't understand.

If I remove the driveshaft and the noise goes away, I am not sure how we can say that it is the driveshaft. Couldn't it also still be the VC, or rear end? It seems to me that the only thing I can prove by removing the DS, is that if it continues to make the noise then I would know that it is not the driveshaft. Please correct me if I am wrong. I want it to be as simple as you say.

I had my father take it for a ride last night; he thinks that the metal shhhhh sound is a rattle; maybe the disintegrated insides of the cat, or maybe a heat shield.

One other thing that I think that I noticed about the thump is that it as the car warms up it seems to not be as bad, or happen as often. Also it not only happens when I let off of the accelerator, It also sometimes happens when the tranny shifts.

Again, thanks for your help, all comments are appreciated.

When I got the car it had 4 new tires. Unfortunately cant tell what was on before.

Really sounds like a driveshaft.
As for removing the shaft, the rear and the viscous coupling are still turning. If the noise goes away, 99% of he time it's the driveshaft. VC's really don't go bad all that often, driveshafts do. At some point in an early Volvo AWD's life, the driveshaft WILL have to be replaced

[JoeJoe]

Ok, so here is the update:
I removed the driveshaft and I think I located the source of the clunking noise. With the driveshaft out, I can push up on the VC, dropping it creates the thumping noise that I have been hearing. I am guessing that this is not normal and that the bushing shot; Ill have to pick up a new one at the dealer tomorrow.
I then decided to take the car out for a test drive; well, the metal grinding noise is still there, its different now. I used to hear the grinding periodically, now it is constant and increases with speed.
It couldn't just be the driveshaft. Actually the driveshaft looked good, at least through my eyes. Center bearing looks good.

[greenxc70]

I am having the same problem on a 2000. I had my brother who is a mechanic put it up in the air at his shop. I shifted the car in and out of drive and reverse while he checked it out. There is a mount at the front of the Viscous Coupling. The rubber bushing had slide out and now the VC is sitting metal on metal and moves when I shift. I am trying to find a replacment for this mount. I'll let you know what I find unless you find something first. I hope it won't mean replacing the whole VC which I did about a year and a half ago.