So I was checking things out under my car, and I happened to notice this crack! I don't recall hearing any cracking or thumping when shifting gears, but I did on occasion hear something backing down the driveway in the morning when I went down the dip onto the road, but I doubt this is at all related. The pictures show the crack viewed from the front of the car looking back on the casing. You can also see that where it's split, there's a piece that's shot out and is missing now. There is no other damage around the crack and the rubber mount part that protrudes out past the housing where the piece of metal is missing - the rubber mount protrudes slightly, has no signs of damage, and also my plastic undercover is in one piece... The car still has the CDV in it and I'm not a fan of dropping the clutch, so I'm really at a loss how this has happened :hmm: .
It's somewhat concerning, if it gets worse and lets lose and/or twists out the whole assembly. The car is a bone stock 325xi with 140 km in Canada.
I've been searching a bit, can't seem to find much... It unfortunately looks like a bottom out but this isn't the lowest part of the car which I would expect to get nailed, and its also sort of backwards - I mean to say: if i bottomed out onto something and ran into it would the front where you see the crack appear not be smashed out / indented too? I can't say for sure as I've only had the car since mid~2007 ... and never bothered to take the plastic stuff off the bottom before and look... Whenever it broke, its been broken for a while there was lots of corroded aluminum there... which is basically metal which puffs up and flakes off /away ....
The exhaust headers are wet from WD40 as I was getting ready to pull the motor and put in a zhp 330 ... but since I saw this I stopped and wanted to know if this is something that commonly fails but just no one bothered posting because the XI numbers are so few....<sigh>
In either case I'm going to replace it - I'll keep the old one and have it welded if possible and push the bushing back in and see if it splits..
I believe the rear diff plug weeps a bit too, I remember seeing this on a few of my friends BMW's I've been under too (older ones). I'm sure some plumbers tape in the threads would slow it down, but its never enough I've ever seen a puddle from it...
Thanks - I've found a local one for now. The guy at the garage figures the two metals corroded and caused this somehow... either way its a boo. Hopefully the old one can be welded for spare. Since it doesn't seem to be a common problem im not going to do with the new one but install it, spray it with rustcheck and ensure i don't run over anything !
No need to change the bushing - that part is still good, its the surrounding material which im worried about breaking... of which one of two things can happen. a part breaks off and that's the worst, or it breaks off and splits further from lack of reinforcement and leaks gear oil everywhere, or worse puts more twisting force on the transmission/mounts causing more fun ... I can always wait till it really breaks to fix it - yes. Maybe worth doing that, not sure....hmm...
I have the same crack on mine also. I hit a big rock driving on a gravel road (rock was half burried into ground, it didn't move).
You (or PO) must have hit something.
I haven't looked under my car at this yet, but I have the same "noise" problem
"I did on occasion hear something backing down the driveway in the morning when I went down the dip onto the road"
I have this every time I back into my garage, there is a bit of a dip. I also hear something when the car goes over dips in & out of parking lots... a creaking noise. Pretty sure it's not the sub-frame, but I will have a look ASAP to see if I have what your photos show.
So it seems that either it broke from running something over or corrosion, in either case I'll change it next year when the weather is warm and see if it fixes that noise situation ... its getting a little cold now, and that piece has been broken for some time if that is the cause, so leaving it for a while longer isn't going to matter much.
But to be honest i'm not convinced that is indeed whats making the noise, let me know what you find....
thanks
Jonathan
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