Hello - Replacing the Front wheel bearing on a 2013 BMW X3 (3.5) and I am trying to locate the torque requirements for the 4 star head bolts that hold it to the knuckle.
Also can anyone confirm the main wheel collar bolt torque (the large one with the Spring) is 140 NM? I found reference to that on another forum - but unsure if that is the correct torque..
I found a site that listed the tightening torque for the "Output shaft to the Wheel Bearing" (listed as Collar Bolt and Compression Spring) as 210 Nm
The site also listed the Wheel Bearing "Screws" (Replaceable) as 80 Nm
I've got an '08 E83 and I am at a loss for information on the vacuum operated flapper valve at the root end of the tailpipe. I have the now well-known E83 rough idle and I am wondering if that vacuum line is a source of a vacuum leak causing the rough idle. I am looking for the solenoid that controls it. I am assuming that it is controlled by a solenoid somewhere because I think it is operated by the engine controller. The other possibility is that it is operated directly by manifold vacuum. In that case where is it plugged into the manifold? I cannot find any information in my Bentley Manual or in the parts breakdown at: https://www.realoem.com/bmw/enUS/select?vin=WJ09460 . Is there anybody out there that is acquainted with the location of the solenoid or have any information that can help me? Even information about when it is supposed to operate, actual vacuum source and is "vacuum on" open or closed? If I can find the solenoid I plan to plug the vacuum line there instead of at the muffler. I have crawled under the car an checked the flapper valve and it appears that the diaphragm is busted because pumping a vacuum directly on the valve just sucks air and the lever arm never moves. Today I picked up some vacuum plugs at the auto parts store and I am going to plug the line right where it plugs into the valve and see if the idle gets better. In the long run I want to plug the line right at the solenoid that controls it or unplug it if that is the vacuum off position but I cannot find it. Any help out there?
AceEngineer
Edit: My bad. I thought I was starting a new thread, didn't realize I was inside a thread. Sorry
Last edited by AceEngineer; 05-22-2023 at 12:41 PM. Reason: Put in wrong place
My better half's DD.....2005 X5 4.4i
My DD.......................2008 X3 3.0si
Yes, an air leak to the exhaust butterfly valve could certainly be a massive vacuum leak. There is a vacuum distribution block on the lower end of the firewall from which a line runs to the control solenoid, which is located inside the port side access panel in the luggage area, outboard of the factory tool kit, in front of that side tail light assembly. The vacuum pump is pulling vacuum on that line at all times. The solenoid is electrically actuated, which in turn "supplies" vacuum to the exhaust valve to close it. Check the valve: there should be a rubber tube running up under the rear bumper. If rotted, you'll have to either replace it, or disconnect the electrical connector at the solenoid to prevent it from pulling vacuum on the valve.
Before falling down the rabbit hole of searching for a vacuum leak, look at your fuel trims first at idle. If they're positive, but <3%, a vacuum leak isn't your cause for rough idle. 5% can cause some hiccups, 8% some hunting, and 20% a DTC for lean condition. If the data supports it, either a smoke test or unlit propane are the best ways to find a vacuum leak unless you see something obvious. Don't forget, every oil leak is also an air leak, so if your engine is leaking oil externally, fix that. My most recent 3% trims were due to the MDP o-ring; replacing that sensor (with new ring) dropped trims 2%. Even at 3%, the engine stalled if hot-started after a 10 minute cool-down and immediately put into gear. I replaced the entire sensor simply because 195k miles.
In case anyone needs the torque values for the BMW F25/F26 (X3/X4) front hubs:
Hub mounting bolts, BMW-style:
80 Nm + 90° (31206855906, M12x1.5 coarse-thread, Torx 60)
Hub mounting bolts, Shaeffler-style:
20 Nm + 120 Nm + 90° (M12x1.25 fine-thread, Torx Plus TP60)
Axle bolt w/ compression spring (31206795249, M16x1.5):
210 Nm + 90°
F31 2014 328xd wagon, F25 2016 X3 28d
Bookmarks