Pump or rack? Power steering issue.

colo_evo

Corporal
Jun 6, 2017
159
111
0
Ride
E90 335i MT
Very weird issue with my 07 e90. I could use some expert advice from you guys.

Noticed an issue where my power steering feels stiff and the steering wheel doesnt come back to center after a turn. Like if I'm making a right hand turn and let off the wheel typically it would center itself or at least return very close to center. Right now I have to help it return to center. This behavior is identical making both right and left hand turns. Theres no rough spots or binding in the wheel, it's just stiff.

Driving down a straight road I feel like I'm always correcting the wheel. In the past I could cruise the speed limit with one finger on the wheel keeping it straight and now it takes a firm grip on the wheel and continous corrections to keep the the car centered in my lane. It feels like the alignment is off, but I had that checked and nothing was out of spec. When lifted in the air I'm able to turn left to right freely with the engine on and off.

I've checked PS fluid level and topped it off. No bubbling/cavitation. The fluid is moving around in the reservoir but it doesnt seem like theres a ton of flow going on. My other vehicles have a nice current of fluid moving around in the reservoir.

The power steering is assisting, but I'd guess it's around 50% capacity. Zero whine from the pump and behavior is the same when hot and cold. I sprayed the universal joint at the steering rack with silicone lubricant and that didnt seem to help.

This seemed to appear after I lost the water pump and had the car towed home. My first thought was the tow truck driver knocked the alignment out but that was verified to be in spec. No loose ball joints, bushings or anything in the suspension geomerty.

Vehicle is an 07 with 98k miles. Pump, rack and everyting else are stock. Mechanically the car is stock, no aftermarket suspension.
 

nyt

Sergeant
Sep 15, 2019
335
1
292
0
Ride
2010 335xi
Have you made tuning changes? I noticed after adjusting reported torque values that my power steering was super stiff. I threw out all those changes after i flashed my trans and it loosened up.

Otherwise, could be a strut cap or steering knuckle binding.
 

colo_evo

Corporal
Jun 6, 2017
159
111
0
Ride
E90 335i MT
Have not made tune changes recently. Thats an interesting observarion though.

Next step I'm going to remove the tie rods and see if either wheel independently is hard to move left/right.
 

JimboFresh206

Sergeant
Jan 29, 2018
289
152
0
Ride
335/635/535/533/633
Tramlining is common with worn ball-joints or blown CA/Tension strut bushings.

What you are describing is Tramlining.

Check all of the ball-joints up front and bushings, having a bit o camber wear on the front tires will attribute to this aswell.

Just saw you were towed, some drivers will attach the chain directly to the CA's/Tension struts. This kills them.
 

Bmwfixerguy1

Lieutenant
Jun 5, 2017
875
292
0
Ride
07 335i MT
It's a bad steering shaft bottom line. It will be frozen and seized on the rack so plan on a fight. Bit it's a bad joint in the steering shaft
 

colo_evo

Corporal
Jun 6, 2017
159
111
0
Ride
E90 335i MT
Wanted to come in and update the thread.

A replacement power steering pump resolved my issue.
 
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