2004 XC70 occasional shudder under part throttle

greg850r · Post by **greg850r** » 19 Sep 2019, 11:35

Hi all,
Our Cross Country wagon has developed a slight skip or shudder at part throttle that is intermittent. Does it once or twice usually before fully warmed up, although it happened on a trip last weekend at 60 mph on an uphill grade. It feels like the drive to the wheels slips and then catches usually twice in a row. Then it drives fine. There are no codes.
I'm thinking I should do a fluid change in all drive systems to start out. Can someone point me to a tutorial where I can read up on servicing the AWD?
Thanks

EDIT: Found tutorials and will change fluids but don't know if it will help of course.

Post by **abscate** » 20 Sep 2019, 03:03

Definitely start there with fresh fluids, maybe3 drain and fills?

Post by **- Pete -** » 20 Sep 2019, 23:13

Does it feel akin to accelerating over a garden hose or extension cord?

I’m going to say (without suggestions given from VIDA), DEM pump is on its way out.

If so, this is a good thing! Much easier to replace than trans.

Get the car in the air & run it in gear to test for AWD function. On our 04 XC AWD function eventually ceased completely. Car in gear in the air, the rear wheels barely spun prior to pump replacement. Prior to that the sensation I palpated was much like you describe.

Not much for tutorials on this, but I’ve taken plenty of pictures the several times I’ve done this & would be happy to share how I did my driveshaft removal, filter, pump etc.

greg850r · Post by **greg850r** » 21 Sep 2019, 18:54

- Pete - wrote: ↑20 Sep 2019, 23:13 Does it feel akin to accelerating over a garden hose or extension cord?

I’m going to say (without suggestions given from VIDA), DEM pump is on its way out.

If so, this is a good thing! Much easier to replace than trans.

Get the car in the air & run it in gear to test for AWD function. On our 04 XC AWD function eventually ceased completely. Car in gear in the air, the rear wheels barely spun prior to pump replacement. Prior to that the sensation I palpated was much like you describe.

Not much for tutorials on this, but I’ve taken plenty of pictures the several times I’ve done this & would be happy to share how I did my driveshaft removal, filter, pump etc.

Thanks, I'll put it on the lift tomorrow and check function. Your description is a good one of what it feels like.

Post by **- Pete -** » 21 Sep 2019, 23:32

I replied in the other thread you posted in HERE. To be fair, testing with the wheels off the ground isn't truly a definitive test as the pump can work intermittently, slow death type thing. In MY case, the pump eventually completely failed & so when I put it on the hook & the rear wheels barely spun I knew what the problem was. In your case, it may still be too early & the brushes on your pump motor might still be functioning sporadically thus potentially giving you a false (non-Vida) reading on if your pump is pumping 100%, 50% or not at all.

greg850r · Post by **greg850r** » 01 Oct 2019, 11:21

I just got time to put this up in the air. The rear wheels are not spinning at all. Also there's gear lube leaking from rear differential. Pump motor and unit are dry however so no leak there. I want to service this completely like you recommended. Going to search driveshaft removal for best method now.

Update: Driveshaft is loose. 6 bolts front, 6 bolts rear, 2 bolts middle carrier and 4 bolts middle heat shield all gone. Still can't get the driveshaft to clear at either end so I can get it out. I don't want to take the exhaust off but am running out of other options.

Next update: Exhaust from cat back off. Just heated the two nuts at the flange and it came apart without damage. The driveshaft bent in the middle enough to release it and it's out too. It looks like the fluid leak is from the clutch and not the rear end. It's yellow and too thin to be gear lube and does not smell like gear lube either.

greg850r · Post by **greg850r** » 01 Oct 2019, 19:06

Well I'm learning. I did some damage to the end of the driveshaft prying on it. Hoping you guys can tell me the bad news from this pic.

: Damage.jpg (116.61 KiB) Viewed 1452 times

Here are some pics of the leak. The pump and everything else on the front is dry. I think the skipping sensation was the pump sucking air intermittantly from the fluid level being a little low. I'm going to have to find the leak or it will just happen again. The pic from the rear shows the diff wet most of the way up to the top. Ideas?

: Oil.jpg (109.55 KiB) Viewed 1452 times

: Leak.jpg (166.72 KiB) Viewed 1452 times

greg850r · Post by **greg850r** » 02 Oct 2019, 12:10

I was able to remove and straighten the cap on the CV joint so no harm done, inside joint looked ok.
I took the pump off the Haldex and it took a looooong time to drain but eventually 400ML came out. Then I used a vacuum brake bleeder to suck out an additional 40 ML through the side plug with a curved plastic line that reached (hopefully) the bottom of the chamber. My new filter will be here in a little while. Here's a pic of the pump.

: pump.jpg (72.82 KiB) Viewed 1443 times

Post by **abscate** » 03 Oct 2019, 04:53

Should have posted this yesterday but was a bit jammed. That cap looks more like a protective cover than anything operationally important.

Post by **- Pete -** » 03 Oct 2019, 11:28

Hopefully that leak is just a pinion seal. Is it dead center or more on the left or right? Spose it could be a seal for one of the CV axles.

I’d probably clean it all up most goodest, put it back together and drive it a week. Then try to zero in on the leak location.

Do you have ViDA? If so it’ll tell you if your pump is dead. If not, just plug the pump in and switch the car on. If no audible noise perceptible coming from pump it’s probably done for. I have ViDA & not a fat clue how to use it so I do everything the old fashioned way & that’s how I figured my pump was dead.

I have a feeling that even though it appears you had a leak there was still sufficient fluid level. 440 ml is still quite a bit & the pump sits pretty much at the lowest point of the housing. Not saying low fluid level cavitation is impossible but I kinda doubt it. My guess would be the pump is flaking out.

Out of curiosity, did you suck the gear oil out of the final drive? There are 2 fluids back there: gear oil for final drive and AOC/Haldex fluid in the Haldex. They are kept separated by a single shared seal. People have talked about failures of this seal, I’ve never personally seen one fail. If it does, AOC fluid can move into the final drive (not a big deal), and conversely, gear oil from final drive can move into the Haldex/AOC (not a good thing). You said the AOC/Haldex fluid was super slow to drain. AOC fluid is pretty thin fluid & should drain pretty quickly (if you have the filler cap off). Even faster with the filter removed.

I wouldn’t worry about that cap. Straighten it out best ya can, grease the hell out of your flanges & CV end caps before you reinstall the driveshaft (for easier disassembly next time). Get your grease gun nice and warm & use a needle to inject grease into the tiny holes on the end caps (dead center, middle of CV joint endcaps).