Hi, i have a volvo xc70 with 250k miles. The awd stopped working. Driveshaft spins when driving forward so im guessing its the haldex. I checked the haldex pump by connecting it to an external battery and the pump turned on. Haldex fluid has never been changed. Could the filter and fluid be so old that its not working or is something like the dem or pressure sensor more likely.
Thanks
> "Hi, i have a volvo xc70 "
What is the year please. Make sure you provide all the info requested in our instructions. Thanks.
That fluid is beyond shot. Like @Doc said, that needs to be serviced every 50k miles.
Haldex is probably shot due to long-term lack of maintenance.
Since the rear wheels still spin slightly when off the ground would servicing the haldex at least help or is it completely shot?
You can try it, but the Haldex is a pretty complex and finicky setup that falls apart when not maintained. It's not like an old Jeep or 4WD truck where you can get away with deferring maintenance.
https://www.eco-torque.co.uk/post/haldex-control-faults-fixes-for-your-haldex-unit-eco-torque-ltd
At 250K miles, the Haldex fluid is probably sludge. It is supposed to be changed, and the filter, every 50K miles.
Driveshaft spins when driving forward
Can you elaborate? Driveshafts exist to spin.
I meant that the transfer case/angle gear must be working since the driveshaft spins with the front wheels so it must be something in the haldex not the transmission/transfer case.
And how do you know the awd doesn’t work?
When in grass or snow only front wheels spin. Also when all wheels are off the ground and in gear the back wheels spin very slowly compared to front.
when all wheels are off the ground and in gear the back wheels spin very slowly compared to front.
Your vehicle wasn't designed to have all wheels off the ground. This is not an accurate way to test any AWD system.
When in grass or snow only front wheels spin.
Could the filter and fluid be so old that its not working
It's a complex system involving hydraulics and oodles of electronics. To diagnose it you would have to take it to someone who specializes in this equipment, knows how it works and how to diagnose it. This will be a small group of smart individuals, and they will likely be employed at dealerships and specialist drivetrain shops which are few and far between. Most shops will tell you to replace the whole system.