2003 XC70 - Loss of rear wheel drive (FWD only, AWD not working)

[Brandon_K]

I finally got a chance to tear into this tonight. I !#$*!$)!@#'ed Volvo every which way possible tonight. It took the better part of 2.5 hours to get out the socket head screws that couple the drive shaft to the differential due to rust, thread locker and simple deterioration. And of course I'm doing this on ramps in my driveway at night, 31 degrees.

Does anyone have any tips on getting the driveshaft disconnected from the AOC input yoke? There is no good place to smack or pry on and since I'm in the Northeast, rust has done a wonderful job of making the two pieces act as one. I managed to smash the metal boot cover loose, but that does no good. Since the input is cupped (it looks like it's a vibration dampener as well), it's just miserable.

Is it even possible to pull the driveshaft off of the rear alone, without dropping the entire shaft off of the bevel gear? I only need to get it off of the input of the rear diff enough to get access to the pump. I gave up on that tonight, I had no more fight in me, instead moved on to other things.

I "rebuilt" the salvage pump. Completely disassembled and cleaned all of the parts (the screen was pretty bad) as well as pulled the motor from the housing and gave it a good once over. Brushes were in great shape and shockingly very little carbon came out of the can on disassembly.

In terrible news, I pulled off the DEM as I was going to swap sensors from the salvage unit. When I pulled it off of the housing, I heard something I didn't want to hear. The sound of sand inside of a aluminum housing. After disassembling the entire DEM, this is what I was left with;

Haldex / Volvo should be ashamed, absolute garbage seal design on this unit. The amount of corrosion all over this car is shocking to say the least. I have a 99 Wrangler (that has been abused nearly it's entire life), a Saturn 10 years older then the XC70 and a 04 turbo Jetta that are all in significantly better condition as far as rust and corrosion go. I've attached another photo, this of the differential housing. Entire parts of the housing have corroded away. Its hard to get a sense of dept in the pic but the aluminum that's missing on the housing around the rubber bushings is at least 3/16" thick. And it's just simply gone!

Anyhow, I cleaned the entire PCB. Most everything looks OK after a mild cleaning with some deoxidization solvent and a soft nylon brush. No obvious blown components. No obvious smoked traces. There are a few solder pads that I'm concerned about and I may meter those out and run jumpers if need be. Being that the pump runs, I'm not sold that the DEM is junk. Of course, just because the pump runs doesn't mean it's running at the correct speed as there is obviously a lot more going on in the PCB than just running the pump, or rather, it's getting a lot more data TO run the pump properly.

As it sits my current plan of attack is to get the driveshaft out of the way (tips, please!) so I can service the rest of the Haldex unit. I'm going to drain the fluid, swap pumps, swap sensors, new filter, new fluid. I'll put the DEM back together enough to see if I get rear drive back. If I do, I'm going to pot the entire DEM unit myself as I have potting compound on hand. If it doesn't work, I guess my only other option is to sell the car as a FWD model and find a suitable replacement (I test drove a new V90 CC a few nights ago...) or cough up the $500 at Xemodex for them to go through my DEM and refurb it.

No matter what, I need to put it all back together by ~4pm Chirstmas Eve as it's the vehicle I'm taking to KY to see family for the holidays. We're supposed to get snow on Christmas day which I'm absolutely dreading in this car right now. My RWD sports car did better in the snow today than the Volvo did.

[jonesg]

And of course I'm doing this on ramps in my driveway at night, 31 degrees.

Does anyone have any tips on getting the driveshaft disconnected from the AOC input yoke? There is no good place to smack or pry on and since I'm in the Northeast, rust has done a wonderful job of making the two pieces act as one. I managed to smash the metal boot cover loose, but that does no good. Since the input is cupped (it looks like it's a vibration dampener as well), it's just miserable.

Is it even possible to pull the driveshaft off of the rear alone, without dropping the entire shaft off of the bevel gear? I only need to get it off of the input of the rear diff enough to get access to the pump. I gave up on that tonight, I

Ar cough up the $500 at Xemodex for them to go through my DEM and refurb it.

No matter what, I need to put it all back together by ~4pm Chirstmas Eve as it's the vehicle I'm taking to KY

I would seriously put it back together for now.
Rear coupler can be separated by putting a bolt in one of the unthreaded holes on the rear face of the coupler, hit the bolt with impact hammer to push shaft out, you may need to drop the center support.

There are cheaper options to rebuild the DEM.

[jonesg]

https://us-shop.bba-reman.com/shop/vehi ... le-repair/

[abscate]

If you put 4 steel rim and real snow tires on a FWD Volvo it will go any winter weather in NA just fine.

All 4 rims and no " all seasons " please

[vtl]

Mind sharing your reasons? I've never driven a P3, but it's really hard to find a low mileage P2 and I really love the body style on the P3. Plus I drive at night a TON so I'd like to find a model with HID headlamps.

Rust under chassis and under the hood on a brand new car. Thin body panels, thin painting. Squeaks everywhere in the cabin. Crappy leather. Tiresome driving experience. Ridiculous dash controls. Trunk panels are falling out all the time. Master brake cylinder broke a year later and it took 2 dealers, Volvo Cars of N.A., Swedish HQ, small parking lot accident and brakes bleeding done by myself capturing air coming out of two lanes on a video.

This is on a new XC60 in a Platinum trim.

[jimmy57]

I mentioned disengaged CV axles as a place to start as the likelihood of rear drive being off is high as you have found. The car is front drive permanently and then on that 6 cylinder model you have the offset gearcase and the bevel gear. The offset gear is driven by the final drive carrier and will turn if the trans gets into gear. The rear driveshaft should turn if the bevel gear connector spline is OK. On that model those have a very low failure rate. The crunching noise you described is what happens if the trans goes into gear but has a slipped or broken CV axle and a non functioning AOC (Haldex) unit. The trans is spinning final drive and when you put it into P the cogged drum is turning w/o wheel turning and the drum is spinning so you hear the whizzing noise until it slows and then the parking pawl falls into drum with a thud.
On some AWD vehicles there is an interaxle diff and loss or either end will give no-go. The XC90 design has no interaxle diff so that type failure can't occur. DEM 001 and DEM 002 do put the AOC offline but that alone is not going to cause it not move any wheel.

[E Showell]

"AOC"?

[SuperHerman]

Brandon - looks like the seal was compromised and water found its way in. Looks like a cell phone that got wet and never fully dried.

Any update? I would do the same as your plan - fix any bad pads with jumpers as needed. Final clean with correct electric part cleaner or alcohol. If it is not too hard to reinstall or if you can tie it up temporary you can test it out. If it works find something to seal the board with, like the green resin used at the factory. Then do a good job sealing it with some quality silicon on both sides of the channel, insert gasket (maybe soak gasket in some hot water to get it to re-shape) and reseal. Apply an outer layer of silicon and let it cure for a day then reassemble. Make sure any outside seal is smooth with no bumps where crud can build up, maybe tape, silicon, smooth and then remove tape so it is "factory" like.

[XC70Rider]

..... Not too cheap, but you can get one for VW for 1/2 of price.

Also driveshaft is bad too because of age and mileage, it needs a new CV joints and at least a new rubber around center bearing.

P3 is worse than P2 all around, honestly.

What's the VW matching AOC oil pump for our P2s? The cheapest Volvo AOC oil pump, 30783079, I can find is $280 on amazon.

Giving thoughts of throwing on a new AOC oil pump before my 12 year one starts failing. With a rebuilt driveshaft and new oscillation damper installed then installing a new oil pump won't be much of a hassle. Removing the driveshaft keeps getting easier each time.

Edit:

Is this the matching pump you're referring to?

https://www.ecstuning.com/b-genuine-vol ... av598549a/

[cn90]

I have a 2005 XC90 2.5T AWD is now FWD.
The 2006 X5 3.0i AWD...the BMW xDrive engineering is much better.

Volvo AWD system is an afterthought, since "the FWD version was already available, let's turn it into AWD..."
The sleeve on the transfer case is a problem. The Haldex and its circuitboard (as posted) is a problem.

I agree with abscate, I bought 4 rims and install winter tires and my 2005 XC90 is running on FWD, not AWD.
Another benefit of FWD is that: it consumes less fuel than AWD.

Just let go the AWD thingy, stay with FWD...