I recently did a complete power steering system flush on my 2001 325Xi (75K miles), plus fixed some leaks in an effort to see if I could get the steering to loosen up a bit. I know that the AWD steering is a little stiffer than the RWD, but this is much worse now than it was a few years ago. My pump didn't make any noise before the flush and still doesn't after the flush. The steering doesn't jerk or stutter. It's just stiff, like the pressure is low in the rack. The pump makes a small load noise when the wheel is at either extreme, but again, no noise in between. I replaced the ATF with Red Line D4. The original fluid was black and had the consistency of dirty water. Here is my flushing procedure: 1) I replaced the return and supply hoses, plus the reservoir before starting the flush (they were leaking) 2) I disconnected the return hose from the cooling coil and raised the end so that it was higher than the reservoir (to prevent fluid loss during the procedure. I just zip-tied it to the reservoir to keep it out of the way) 3) I reconnected the old return line back onto the cooler's return fitting and route/aim it down to a drain pan. 4) I filled the reservoir with Red Line D4 5) (Since I was changing my belts anyway, the belts were off the pulleys, so) I looped an old belt around the power steering pump pulley and routed the other end up through the engine compartment where I attached a cordless drill. The drill had a 4 inch grinding wheel attached, which made a great driving pulley of sorts. 6) I triggered the cordless drill to spin the pulley in the pumping direction (clockwise, looking at it from the front of the car) and watched the bad fluid blow out of the dangling return line. 7) As the reservoir drained almost to the bottom, I stopped and added more fluid. 8) Wash, rinse, repeat until clean D4 was streaming into the drain pan. 9) Disconnect the dangling return line and then reconnect the new, tied up hose (quickly, since there was still fluid in the reservoir). 10) Clean up all the drizzle, start the car and bleed the system by slowly turning the wheel back and forth, lock to lock about 6 times. 11) Top up the reservoir and drive. So, my question is, should I now be suspecting the pump? I guess it doesn't have to make grinding noises to be bad, although that seems to be the usual indication. Also, I read on various forums about replacing the high pressure line. Someone suggested there was a filter in this line? Mine's not leaking, so I hadn't considered changing this out, but I'm not familiar with the internals. Then, there's the rack itself. Mine doesn't seem to be leaking into the boots. What do you guys think it might be? Thanks in advance for any ideas! Ty
Pump? Hard to diagnose over the internet, however there have been quite a few bad pumps and steering racks seem not to be problematic on 3 series BMW's. Since the fluid looked dirty I'd say that is enough evidence that the pump no longer is up to snuff.
Probably the pump Thanks for the reply, Doug. The pump makes the most sense to me too. I've found an OEM pump (LUK LF-30) for $365 through RMEuropean.com. Kind of pricey, so I wanted a sanity check before I ordered one.
As a note, BMW pumps have a shaft that is designed to shear, so there is almost never a noisy pump. They just quit working. Also, I have a pump that I bought for my e46 from a used parts supplier and the line connections ended up being different. If you can send me a pic, or describe your connections at he pump I'll see if it will fit. I'd sell it for what I paid. ($150)
I need to re-open this thread. Can anyone suggest the best way to diagnose a rack? How do you know if a rack is bad? My rack doesn't leak fluid into the boots and doesn't grind when turning in either direction. But I still have stiff steering, even after trying 2 new pumps. There are no visible leaks anywhere. The steering pump doesn't whine in either direction. I can, however, make it strain when steering all the way against the left or right extreme. I've tried the easy stuff, like tire pressures and alignment. Suspension ball joints, strut bearings, etc are all tight, clean and move freely. However, I am imagining that if there are hydraulic leaks in the bores of the rack itself, perhaps from worn bores or worn internal seals, there could be hydraulic fluid leakage around the pistons. This could possibly explain reduced steering assist. The weird part is, whatever might be wrong isn't obvious. I'm not sure how to diagnose a rack that doesn't leak or chatter when turning. Any thoughts on some diagnostics would be appreciated. Since rebuilt racks are $1K+, I want to be sure before blindly replacing it. Thanks, Ty
