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Discussion Starter · #1 ·
Hi Everybody,

today I did some maintenance fluid changes on my XC90 T6 2004. One of the things I did was flushing the power steering system with Pentosin CHF 11S (I did this once already about two years ago). Leaving the shop where I rented the lift, everything seemed to be fine but then after about 10 minutes of driving there was a loud bang from somewhere near the right front wheel and an immediate loss of power steering assistance.

Has anybody experienced something like this? What could it be? Right now I think it might be the pump, but does this make any sense? Why would it go bad from a fluid change? The serpentine belt on the pump is in place and doing like it should but I noticed that the fluid in the power steering reservoir isn't moving anymore when the car is idling. Normally there was a slightly visible stream of fluid in the reservoir from fluid being pumped through the steering system.

Help and ideas are very much appreciated. Thanks a lot!
 

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Discussion Starter · #2 · (Edited)
Any ideas? Is there a way to isolate if the pump is the culprit? Would be good to pin down the problem somehow before starting to swap parts...
 

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Discussion Starter · #4 ·
Well there is no fluid leaking anywhere and the reservoir level is where it should be. I really hope that it's not the steering rack...
 

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Discussion Starter · #5 ·
Found a used and well priced original pump on Ebay. Hope it will cure my problem when it will replace the old one in the next few days.
 

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I saw on an old MF backhoe where a guy did something wrong and there also was a loud bang. The splines to the pump shaft were stripped.
 

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If it is a consistent no power problem, it could be isolated to the pump. Sometimes when there is an issue with the steering rack, you can feel differences in resistance or notchiness while turning. In either case, if you are replacing the pump, do a thorough flush of the fluid more than once. If there are any metal shavings in the fluid, it will hurt the steering rack and the newer pump.

Do you see any metal in the fluid now?
 

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Discussion Starter · #8 · (Edited)
Yes the No-Power-Problem is permanent. I didn't see any metal shavings but will examine more in detail soon and will flush several times as advised (Think am also gonna put a magnefine filter in the return line). Got the used replacement pump today but unfortunately it arrived with a broken pulley. Ordered a new pulley for around the same price as the used pump, haha, stupid. Let's see if I can find some friendly auto repair shop that is willing to lend out this special Volvo pulley tool thingy...
 

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Discussion Starter · #9 · (Edited)
Had no luck finding a repair shop with the pulley puller tool, not even the company ZF that manufactured the pumps here in Germany was willing to help. So I ordered another 120bar used pump from ebay (from a 2003 V70R) with an intact pulley. Installed it in the car yesterday and the power steering assist came back online :)

But: When in park or in very slow turns and turning the steering wheel to the left, there is some kind of a whining or flow noise coming from the footwell area somewhere. (Turning to the right there is also a minimal very subtle noise but it's much more noticeable turning the wheel to the left)

What could this be? Is the used pump I installed maybe not good anymore? But then why would this only happen when turning to the left? I don't know much about how a steering rack works but could the rack need more pressure when turning to the left and the pump can't supply enough power due to age? Or would it be more likely that the rack was somehow damaged? (Fluid level is alright, and system was burped, I am confident it is free of air)

Any ideas?
 

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I had a shop hook into my PS lines when I had asked for a transmission flush. There was oil everywhere and soon after the pump went. The first rebuild whined all the time and I returned it. The second one was good. That was on a 98 Windstar. I've heard so many of them whine. I hope Volvo uses a different pump.
 

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Keep on driving it to see if it subsides. New fluid may need time to work with a used pump which was dry for some time and to remove trapped air you could not get out. If it is still an issue after driving it for a week, then it might be the used pump struggling.
 

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The pump is meeting additional load on the turn to left, and whatever that is may be why the original pump grenaded. One thought is that a hose is de-laminated internally, especially since all issues began after replacing the fluid. Perhaps a portion of interior hose was lifted during installation and is now acting like a check valve?
 

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Discussion Starter · #13 ·
Okay, thank you gentlemen for your very helpful comments, much appreciated. I am positive that none of the lifted oil hoses were kinked. Will keep on driving for a week and see. In case the noise won't disappear, I will first swap the used pump with a new one from Bosch. Sure the fact that the whining is not really coming from the pump but from the left side of the footwell (probably steering rack) makes me wonder if it can be the pump at all but who knows, things can be complex and weirdly connected to each other sometimes, so let's see...
 
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