Random bolt spat from car?!

R0n1n

Member
I was 5 metres up the road from my house yesterday when there was a loud sound from the near-side front. I immediately stopped and found a bolt on the road (images below). I parked the car sharpish back on the drive and daren't drive it since!

Car started OK today and sounds fine, I moved the car up and down the drive slightly and the wheels are turning left / right. I pushed down on the suspension either side, no noises etc.

I've looked (well tried to look) underneath the car and from my limited view there is nothing hanging down.

Photos of said bolt below, I know it's a long shot, but does anyone recognise it?! Towards the end of the the bolt it does begin to get a bit black and sticky.

IMAG0272.jpg
IMAG0271.jpg
 
I thought that too, but it made a hell of a racket. Googling seems to suggest it could be a transmission engine mounting bolt... maybe!
 
Looks to me very much like the bolts that bolt into the diff. Holding the input and output shafts. I would want to have a look around there if I where you.
 
Looks like an M8 or M10 Torx stud/bolt, they are used on lots of cars. Typically fitting through in to a captive thread e.g. they are used to locate parts on the exhaust system and manifold, on the brakes, right through to seat brackets. Needle/haystack I'm afraid and it may not even be yours :|
 
R0n1n said:
just took a video of the engine, does this sound "normal"?

https://youtu.be/ajF951xhZ8c

My car has an occasional tick from the well known HVA issue if it hasn't been driven hard for awhile, but nowhere near as pronounced and loud as that. Hopefully someone can confirm.
 
Thanks for comment. It is normally not so loud I think, it always has done it when I first start off, but tends to go once the engine has warmed. I've never left it just idling like that before. But it does seem quite loud!
 
R0n1n said:
Thanks for replies, it's a 3.0si. 2006, 54k miles.

If you measure the diameter of the threaded part (probably 8 or 10 mm) and length under the flange head, should be able to narrow down the source.
 
Hi,
Is the bolt alloy, if so it's from the engine/gearbox.
If it's steel it will be from the differential input or output shafts (As MM has said).
Stu.
 
Looks like a bellhousing bolt if it is from your car. How long is it? And what M measurement? Looks too large to be prop shaft bolt. Also if it's deceptively light its an aluminium bolt and could then very well be from the box bellhousing.
 
Thank you again for the replies! Really appreciated!

Just to add, I've measured the bolt.

It's M8, length = 40mm, of that, thread length = 25mm (so the body length is 15mm)
 
Are there any other nuts lying around? If the bolt came from your car the nut could be close.

It's most likely just that the bolt was picked up thrown into your arches by the Tyres, hence the noise, so as others have said might not even be yours.

Driving over loose gravel makes me cringe as the Tyres pick everything up and throw it into the arches , sounds horrible.
 
R0n1n said:
Thank you again for the replies! Really appreciated!

Just to add, I've measured the bolt.

It's M8, length = 40mm, of that, thread length = 25mm (so the body length is 15mm)

If it is yours looks like Machine Monkey called it right being used on the rear axle output shaft which seems to be one of the few applications on the 3.0si . Time to get down and dirty :)
http://bmwfans.info/parts-catalog/E85/Europe/Z4_3.0si-N52/dec2007/browse/rear_axle/output_shaft
https://www.turnermotorsport.com/p-7936-rear-axle-output-shaft-torx-screw-e30-e36-e46-e9x/
 
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