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      11-14-2018, 07:22 PM   #10
PhaseP
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Drives: 325XI
Join Date: May 2010
Location: Earth

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Here is what I think going on, based on my knowledge of my XI and a few others who posted popping out passenger side CV axles in the past:

The engine mount bracket (support) bolts on to the engine block with aluminum bolts. You can find the part number here, number 7:

http://www.realoem.com/bmw/enUS/show...diagId=22_0113

Being an N52 with magnesium block, anything bolts on to the block uses aluminum bolts not to cause galvanic corrosion, and itself is aluminum.

There are some engine mount replacement DIY's that instruct to remove the engine mount bracket (support) to aid in replacement of the engine mount, especially on the passenger side. But the engine mount replacement DOES not need the engine mount bracket to be unbolted from the engine! I have replaced my mounts without doing it and DIY from places like Pelican Parts, FCP Euro also show doing the engine mount replacement without removing that support bracket, rightfully so.

Because the bolts are aluminum, they are one time use. Reuse them, like removing them for aiding in engine mount replacement, you risk breakage like this case.

I would bet someone in the past removed those bolts and reused them without replacing with new ones.

Since the heads are broken off, there won't be any tension on those broken bolts and they will most probably come out easily, unless they are galled.

About the CV axle that came apart like that; that is not press fit that got broken. It is made of two separate pieces there, and the two pieces are held in place by the boot only when axle is not installed on the car. When axle is installed on the car, the geometry of the suspension components do not allow each part to move away far enough from each other such that the boot will tear out and two parts will come apart. In your case, because engine mount bracket bolts broke off, engine moved down and swung to side causing extreme enough movement inside that inner CV joint and the two pieces came apart. Whether you can put it back in and reuse would depend on if the bearings and the surfaces they ride on had sustained any damage or not. There are 3 small wheel like round bearings that ride on the 3 guides on the inner CV housing, these should have mirror finish on them still. Any nicks on them will cause the CV to not last long even if you put them back together. And then these small wheel like bearings inside them have needle bearings they should be fine too. Lastly the inside surface of the inner CV housing that these ride in and out has to be still smooth. Obviously if anything was bent, can't reuse.

About the oil there, some of it the can be due to the axle grease that came out, but looks too thin for grease. The other possibility which my guess would be, is the front differential oil leaked. The front differential oil right side seal is where that right side axle enters the oil pan. If the axle was hit that hard, the seal there could easily have been disturbed to leak the differential fluid. The front differential is bolted on the left side of the engine oil pan. There is a tube that goes through the oil pan where the straight section of the passenger side CV axle is inserted and how it reaches the differential. This tube has differential oil in it splashing around and wheels turn.

By the way there are two potential leak points for the differential oil, one is the axle seal, and the other is an o-ring that seals the "pedestal" that is bolted to the oil pan and the oil pan surface. The axle goes into this pedestal and the axle seal is on this pedestal. It is that box like thing that is coming out of the oil pan.

Search this forum for "popping" or "broken" "passenger CV axle" "half shaft" you will find similar stories.

One example:
https://www.e90post.com/forums/showt...nt+axle+broken

Last edited by PhaseP; 11-19-2018 at 01:45 AM..
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