Sudden noise

[Birdman]

Leaving home for London, 100 metres down the road travelling about 10mph I hear a sudden loud bang from front left side, in the wheel/underbonnet area, sounding like a catastrophic component failure.Everything apparently normal otherwise so I return to my front door and park up.

Thinking it could be a failure of the LHS spring or adjustable shock absorber (its a W210 E55) I get the car up on a ramp. Nothing in front wheel bay broken - springs ok and properly located, bushes intact, wheels rotate correctly, steering feels good. Road test indicates braking absolutely normal, no warning messages, everything apparently ok. Any ideas what to look for?
- Birdman

 

[Birdman]

Took the car to an independent mercedes specialist who demonstrated that the front LHS spring had cracked at the very base where it seats into the cup. The fracture could be felt rather than seen, which is why I missed it during my visual inspection, and this must be the cause of the 'pistol shot' I heard. It's an AMG component and I'm told it takes about 2 hours labour to replace both front springs which is the recommended action. It can wait until next month, when it has its two year lube/fluid/plugs/filter/everything service.
Has anyone heard of such a thing happening to a sub-four-year-old car? I thought it especially odd that the failure occured at 10mph on the front drive, which is smooth, and not while crashing into a pothole, which is something I have so far managed to avoid.
- Birdman

 

[Brian WH]

Has anyone heard of such a thing happening to a sub-four-year-old car? I thought it especially odd that the failure occured at 10mph on the front drive, which is smooth, and not while crashing into a pothole, which is something I have so far managed to avoid.
- Birdman

They can go at any-time as they are under a lot of pressure. As you say breakage is normally associated with driving up kerbs or large potholes, but could just be a bad spring.

 

[Birdman]

That makes sense. I'll get the broken spring back to check it out and post here anything unusual (not that I know what usual looks like but I know a man who does).
-Birdman.