318 exhaust woes

[gazza]

2 brand new exhaust back boxes in 6 weeks .....318i cab fitted with cat ...both snappedwhere the pipe goes into the back box ..not on the weld but about 1cm from it both have snapped right through ....whats causing it i have a 3rd one fitted now of a different manufacture (ernst) engine mounts/bushes seem all ok

[jmc330i]

It was 2 new backboxes that broke and in the same place?

Are all the hangers being used on the rest of the system?
Theres one solid mount on the bottom of the gearbox, one rubber mount off the rear subframe and the 2 metal straps that go around the backbox.

[DanThe]

Gearbox mount is very important

[gazza]

yes gearbox mount is new and new mounts above the rear box(rubbers and the 2 bands) but i cant understand why they broke at that point ....if it was on the weld i would blame that and poor quality i now have a ernst box and hope this will be ok ...has anyone else had this problem

[jmc330i]

There is another rubber mount where the pipe runs under the rear subframe before the backbox - is this one being used?

[gazza]

not on my 318 ill check the etk but i dont think it has one

[jmc330i]

The ETK says yes, so it should have one, my 318i touring has it.

It is only bolted to the crossmember so it may of been removed or fallen off due to to the bracket rusting away.

[gazza]

yes all mounts are used still cant sus it out 3 mounts in total

[jmc330i]

This is the one I think you may be missing (red circle)....


Its on the crossmember to the left of the diff. In the bottom left corner of the pic you can just see the hanger and rubber on my 318i exhaust.

I could understand the pipes having a hard time if this mounting isnt used and the backbox/pipes were poor quality.