XC70-2000 @100Kmi. - Growling/whinning pbm

[cchantzis]

My XC70 AWD-2000 with 100,000 miles makes a variable pitch growling/whinning noise either in Drive or Neutral at speeds as low as 10 to 20 MPH. The car makes no noise when parked and engine running. I have replaced front L/R hubs and drive shafts hoping to eliminate the pbm but noooo. Anyway, I did a quick inspection under the car and there is no oil leakage at the Angle Gear (AG). The prop shaft seems solid when I tried to move it. I plan to isolate the pbm by raising the front of the car off the ground, disconnecting the prop shaft from the AG and then starting the car and running its transmission. Even though there would be a "no load" condition, I hope to either hear the growling/whinning noise or not.

Questions:

1. If I don't hear the current growling/whinning noise, then may I isolate the pbm in the prop shaft (central bearing or U-joint) and/or viscous coupling (VC)?
2. My understanding is: (a) there is a central bearing on the prop shaft and near the AG that could be pressed out and replaced, (b) a U-joint at the middle of the prop shaft that can NOT be replaced (even though I have seen a post from a fellow in CT that did so for only less than $20!!! but lots of brilliance), (c) a Viscous coupling (VC) near the end of the prop shaft and near the Rear axle of the car that can't be replaced either, and (d) the AG can't be repaired if it fails (ex. splines stripped) except its seal. Is my understanding correct?

Thanks so much in advance for your thoughts. Much appreciated!

[FCPEURO]

The grinding noise definitely sounds like an issue in the drive train. The best thing to do would be to get all four wheels off the ground, leave the drive shaft in place, and have someone put the car in drive while you stay outside the car and listen for the noise. This really is the only way to isolate it.

Also, if you can put the car on a lift, that would be the safest way to do this. This time of thing is not without risk so I do not take responsibility if something goes wrong.

[holler1]

Another thing you can do is just remove the center driveshaft and drive it that way as long as necessary. Lots of people have just taken them out permanently. I had mine out for a few months. If the noise stops, chances are good the shaft is the problem. You can get a rebuilt shaft from Colorado Driveshaft if needed for about 1/2 the cost of a new one.

[cchantzis]

Here is my plan:

1. Raise the car off the ground, SECURELY.
2. Tie the car from a fixed point, ex. a nearby tree or something so it doesn't destroy anything should somehow get off the stands and start moving forward .
3 Have my helper put it in Drive and slowly raise the RPM to about 2,500, IF required.
4. I will be outside, by one side of the car trying to hear from where the whinning/growling noise originates.
5. Next, I will change the Bevel Gear fluid 3 times while the car is off the ground. Every time I make a change, I will repeat above steps 2 through 4.
6. Hopefully, the noise is lessen and eventually goes away IF it is related to the Bevel Gear.
7. If NOT, then I will disconnect the prop shaft but I don't know at which points. Can you or someone else explain "When you took out the prop shaft, that means you disconnected it at which points? Obviously, you can't take out the short shaft going into the Bevel Gear."
8. IF the noise goes away when the prop shaft is off, then the prop shaft must be replaced/fixed.
9. IF the noise continues, then the Bevel Gear is the problem and must be replaced/fixed.

Many thanks again.

[johngxc]

I'll defer to those more expert than me, other than to say I would not recommend your procedure. You'll put a lot of stress on components, perhaps damage your transmission, and you still won't know whether the viscous coupling (VC) is part (or all) of your problem. I also have a drive train problem (have already removed prop shaft - symptoms gone) and I'm trying to find a test for the VC on this forum (per a response on another forum). All I've found so far is to jack up one front tire, and try turning the tire with a torque up to a specified limit (50 lbs??) but I'm been looking for some time and can't locate a post with a clear test.

If this was my problem, I'd first flush the transmission (instructions on this site). I'm using the Mobil 3309 fluid, and this completely cured a 'hard shift' issue. Note that for my 2000 XC, produced late in the year (Feb), the connector is the green one (P2?) used for later years, and the fluid flowed _out_ of the line going into the top of the radiator.

There's a post somewhere on how to remove the prop shaft. This (IMO) is harder than the post makes it sound. Be SURE to mark the shaft and flanges, and bolts, so you can replace them in the SAME positions if necessary. The bolts may be different lengths - different lengths are used to balance. Also, the newer bolts are a hex size (at least the ones I got from the local dealer) - I think 6 and 8 mm hex, but not sure.

If you locate that post with directions on how to text a VC please post a link here, or on my post on the VolvoXC.com forum (http://www.volvoxc.com/forums/showthread.php?t=16928). My car had a shudder rather than whine, but the suspect components are the same.

[cchantzis]

johngxc,
Thanks for your input. Relative to your pbm, it is clear that since your noise went away once the prop shaft was out, then you can safely exclude the Bevel Gear. You may want to carefully examine the condition of the central shaft bearing and U-joint. Previous posts indicate that those areas typically fail first BEFORE the Viscous Coupling (VC) will do. You may want to scan-review the attached document; it contains literally all posts on the net up to around August 20, 2010 on the subject of "prop shaft, Bevel Gear and Viscous Coupling" problems of XC70 users. Good luck!

[holler1]

There's a post somewhere on how to remove the prop shaft. This (IMO) is harder than the post makes it sound. Be SURE to mark the shaft and flanges, and bolts, so you can replace them in the SAME positions if necessary. The bolts may be different lengths - different lengths are used to balance. Also, the newer bolts are a hex size (at least the ones I got from the local dealer) - I think 6 and 8 mm hex, but not sure.

These are good points on the driveshaft removal. The PDF post above also has a lot of good info. The driveshaft is a two piece design with a universal joint and bearing in the middle and CV joints at each end. The CV joints are attached to the angle gear on the front and the VC at the rear. Mark the bolt locations as mentioned above. Basically, to remove the shaft, take out six hex bolts at each end and tap the CV sections loose from the angle gear and VC. Then remove two bolts that hold the center bearing housing (see picture) to the crossbar below it, loosen one side of the crossbar, and let the shaft slip down beside the crossbar. The crossbar is below the driveshaft but over the exhaust pipe, a little complicated but this is do-able. I'll attach some pictures that might help a little- one of an old and new driveshaft (from Colorado Driveshaft), another other of the end that connects at the front, some pictures of the center bearing housing and the crossbar. These got out of order in the upload-start at the bottom. My experience is that the front CV joint fails due to heat from the exhaust. However, the CV joint makes a repetitive pinging or clanging noise when it fails, not a growl. Other people have had problems with the center bearing.

[cchantzis]

holler1,
Your photos are VERY much appreciated. Now, I think I much better understand HOW to take off this prop shaft, thanks to you