Well I seemed to have found some issues...
The very first thing I did was jack up the car, put trans in neutral, emergency brake is on (but not working that great..should be fine for this test)...

I twisted the driveshaft clockwise and counterclockwise and it moved about 1/4" each way. Clunked heavily in the pumpkin with that movement. No specs in Bentley for this or...

Front U joint into transmission= definitely loose maybe 1/8" of play. I will certainly repair this first but it seems like only one of two noises. Other two u joints seemed firm. This other noise seems to come from/

I wiggled jiggleed and bounce the wheels up and down with the brake all off and car in neutral but nothing obvious. I know its not thorough as taking the calipers and rotors off, but again, nothing glaring.

Should the gears in the diff make so much noise that I hear them ratt a tatt tatt when I rotate a wheel by hand?

Keep in mind this is quite a POP! I hear and it seems to come from further back than the tranny.

What do you think I should do next?
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89 245 'loaded' with a Great Pyrenees

So I took the 245 to an independent Volvo shop today and explicitly told them about all the issues I've mentioned on the "cut the rear end off" threads I've posted.

I told them about he 1/4" play I found in the U-Joint that joins the drive shaft to the tranny and asked them to replace it. They put the car up, and told me there was nothing wrong with ANY u-joints and that it was the output shaft of the transmission and that that play was nothing to worry about.
So I ask you (because the BB search doesn't seem to be working), could it be a bushing, bearing, the shaft?

I instructed them on how to recreate the far-to-often-yet-not-all-the-time loud "snapping" noise which seems to be coming from the rear axle somewhere after I take the car out of park, put it in reverse or from park to drive then accelerate. They could not recreate it and think I am absolutely insane.

I told them I found about 1/8-1/4" of pinion slop. They checked that and said that is nothing to worry about.

The only thing that's not been done by me- and I will do this- is removing the calipers, rotors and checking the axles for something weird. Then bleeding the system again.

They shook the wheels around and found nothing obvious.

The good news is they charged me nothing at all.

The bad news is I'm not insane and this loud "snap" is bad. It's not right I said to their comment of "it's an old car and should make some noise."

So I'm going to beg the owner/manager or have him have a tech jump in the car with me and I'll recreate the noise (hopefully)- even if I have to pay them for the time.

Either that or take it to another shop?

I really need to just pull the calipers and rotors at this point.
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89 245 'loaded' with a Great Pyrenees; 91 245 project

You can sure feel like you’re chasing ghosts when you’re on the trail of some irritating noise. It does sound like you’re building a list of things which are not the cause. Assuming high confidence in those pros with the lift, keep on that list anything they had a good look at, that is, the entire drive train. Unless what’s behind this noise is a really exotic problem--and that’s unlikely--they probably would’ve caught it. The usual suspects those pros knows.

As far as you rear axles: again, they probably belong on the not-the-problem list, as does the rest of the rear end. What fails when you have noisy axle-shaft trouble is the axle-shaft bearing. As it fails, the bearing begins to roll less and less well, with the rolling ultimately becoming a grinding. Failed bearings will announce themselves. Although the noise of a failed bearing will change with load, it is not an intermittent noise but a continuous one. So far, you have not described such a noise.

If you do pursue your ghost to the area of the axle shafts, this might help a little: You can get the rear calipers clear of the rotors without opening the hydraulic brake lines, meaning you won’t have to bleed your brakes. The steel brake lines are attached with bolts and clamps to the axle tubes of the rear end; loosen those attachments and you’ll have enough movement to get the calipers clear. Then, suspend the calipers with some stiff wire secured somewhere on the underside of the car--I think the upper shock mount will work.

The problem with these undercar ghost noises is that it’s hard to locate the source when you’re in the driver’s seat, and it’s hard to demonstrate the noise when you’re not in the driver’s seat. Also, suspension components behave differently--and may make different noise or no noise--when they're “unloaded” on the rack compared to when they’re “loaded” on the ground.

Maybe you could enlist your extra pair of hands to rock the car back-and-forth and side-to-side while you sit at the wheel with the engine off. Brakes on and off, parking brake on and off, in and out of gear. If you could get the noise to repeat on demand, then you could switch places with your assistant, get on the ground and trace the noise to its source.

You might consider whether the ghost noise appeared after an apparently-unrelated recent repair. Just because we don’t have any parts left over when we’re done doesn’t mean we got ‘em all back where they belong. Have you recently done work on the rear brakes? The parking brakes can be tough to get back together. Assuming that you use your parking brake, maybe you’ve got a spring or a cable hanging up in there which prevents those little drum brakes from releasing smoothly. If they are hanging up, they could easily make a pop, ding, clang or clunk when they finally let go.

Good luck with it!

I have something similar to this. my brick has 235K on it. when I accelerate I hear a very loud, consistant rubbing noise in the back. on decelleration the noise changes with a deeper tone. I brought it to my general mechanic and he said the rear axle was bad and the sound was the gears grinding against each other. Any ideas? Could it really just be the shaft bearing?

erik

I would look at the driveshaft center bearing, first - these have made all sorts of different noises. Next likely culprit is a rear wheel bearing - in which case, the noise will change when you turn left or turn right. The UN-loaded side which makes noise is where you find the bad bearing.

If you have a sensitive ear, you may be able to differentiate between a noise which happens at wheel speed versus driveshaft speed... driveshaft speed being roughly 3x faster than wheel/axle speed.
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No one ever went broke underestimating the taste of the American public - H.L. Mencken

Don't ya just HATE it? I chased a noise like that one; turned out to be a bad wheel. Early on in its life, the wheel nuts hadn't been tightened enough, and the wheel could rotate just a bit in the elongated holes. I checked and repaired everything, yet the noise persisted, to a point where I was questioning my sanity, never mind my mechanical ability.

I'm not saying that this is your problem, I'm saying that you are going to find the problem in a very unlikely spot, so check EVERYTHING. Good hunting!!

Nothing I've read here or in your earlier, related thread convinces me the problem is any more complicated than a failed #1 universal joint.

U-joints should have no appreciable play. When they do they can be louder than you'd expect in a manner that you wouldn't expect. And they're dangerous. It does seem that the forwardmost u-joint fails more frequently than the other two.

The rear end you describe seems normal. A little free rotation at the pinion input as you load up the internals is to be expected--the amount you describe is consistent with other happy 240s I have known. The rat-a-tat sound you hear is the normal meshing of the bevel-cut spider gears in the differential. Three shafts meet in the differential: two axles and the pinion. You'll hear that sound any time you hold stationary one shaft of the differential and rotate either of the other two. The sound may seem excessive because the differential internals are turning much more in this test situation--because of the much greater rotation "differential" between the shafts--than they do in normal use.

Volvo rear ends are very robust. Unless there's been leaking at the pinion or axle seals, or unless the car has had very high mileage or abuse, I'd leave the rear end low on the list of suspects.

So, my suggestion is to keep it simple: Don't fix what aint broke. Get that new u-joint in place then reassess. The problem may be over.

You can still have your fun working on all that other stuff, but I think most of it is peripheral to the problem you are trying to address. That makes it not part of the repair, just part of the hobby.

Good luck with it!

Even if it isn't causing the rear end noise, you MUST replace that 1/8th inch slop U-joint... that is imminent mega damage waiting to happen on the freeway when you hit the kickdown!Also note that the driveshaft itself is a hollow tube that resonates and makes drivetrain noise even louder!

In short, fix the U-joints first, then go after the rear end as 1/4 inch slop at the circumference of the pinion flange equals TOAST (assuming the wheels never moved)!

jorrell
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92 245 250K miles, IPD'd to the hilt, 06 XC70, 00 Eclipse custom Turbo setup...currently taking names and kicking reputations!

Jorrell,

That's what I was thinking too. Fix the U-joint pronto.

Second, I was going to swing the rig by a local shop and for a second opinion have them put the car up on a lift and do the same drive shaft wiggle test and see what they said. 1/4" seems like a bit too much. In your experience is just replacing the entire axle assembly easier than dealing with pinion gears? I do know of a 91 sedan with only 89k on it with a full axle.

Finally, taking the calipers and rotors off and fully checking the axles I'll do this weekend, when I want to deal with all that and bleeding the brakes for the umteenth time!

Thoughts, suggestions, anyone else chime in on this?

Thank you!
~jason
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89 245 'loaded' with a Great Pyrenees

Absolutely - fix that bum U-joint, and reassess. Final drive failure is highly unlikely, and I even doubt there's anything in your rear brakes that could make the noise you describe.

Post back with results of your test drive after the U-joint is fixed...

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No one ever went broke underestimating the taste of the American public - H.L. Mencken

I explain what happened at my trusted indie Volvo shop.

No problems with u-joints at all apparently...
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89 245 'loaded' with a Great Pyrenees; 91 245 project

Guess I'm just confused. I thought you found 1/8" slop in your front u-joint, but your shop guy pooh-poohed that.

A universal joint should have *zero* discernible play/slop/lash when rotating it back and forth... I'm still of the mind that if your u-joint has play in it, it needs to be replaced.

Did I misunderstand something?
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No one ever went broke underestimating the taste of the American public - H.L. Mencken

Nope. You got it right. I thought the slop was in my Ujoint (1/8-1/4") but its the output shaft/bearing.
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89 245 'loaded' with a Great Pyrenees