August 2001 E46 B3 cabrio secondary air system.

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August 2001 E46 B3 cabrio secondary air system.

Post by music » Wed Aug 01, 2018 12:11 am

Hi folks. It's been a while since I last posted but I read regularly.

Recently I went over a speed bump at a local recycling site at zero mph with just one bin liner of grass cuttings in the boot (tiny garden). I know the bump doesn't conform so I'm always careful to pick the lowest bit but a parked car blocked my preferred path. The car dropped clean onto the bottom of a downpipe. A solid shockwave went through the bodyshell as you might expect. I called at a friend's local garage on the way home, got it in the air and found a small dent but no scrape marks and otherwise no apparent serious damage.

Next morning I'd got an exhaust blow from around the front manifold area. It cleared after about 45 secs as the manifolds warmed up (same next morning too) so a hairline seam fracture is suspected. It's booked in for a cold pressurised smoke test to find the leak before it warms up then carefully Tig weld it so I've tried to make sure we've got the right gaskets before it gets stripped down.

Here's the rub. Sytner Nottingham tell me these are standard BMW parts as listed on page 11 of the Alpina parts catalogue, ie. 11 72 1 435 367 and 11 62 1 744 252 but I'm not so sure. The manifold to head gaskets each have the expected 3 exhaust ports and 12 stud holes but no airways for the secondary air system pipes. I may be thick, and it's hard to see whilst still on the car, but I can't see how that works. Neither can the (knowledgeable) guy at the garage nor could the guy in parts at Nottingham.

Closer examination with a lamp and mirror appears to show each manifold flange and gasket in two separate parts with the air system pipes bolting straight to the head between cylinders 2/3 and 4/5. It's very difficult to see and understand with a reversed image and all the other bits in the way.

There's so little info on the web (do Alpina also keep state secrets?) but can anyone explain or point me to a site with diagrams that might educate us. I can't have the car off the road waiting for Alpina specific bits 'til god knows when.

Many thanks.
E46 B3 cabrio

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Post by Charles » Wed Aug 01, 2018 12:22 am

A while back I had some hairline cracks where the branches join and had them welded in situ without needing to remove the manifold.

Worked a treat :D
Charles
Teacher of Chemistry and driver of ALPINAs - not necessarily in that order ;)
B3S Touring (49/116) - been to the moon and now on the way back!
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Post by music » Thu Aug 02, 2018 2:10 am

Many thanks Charles, and reassuring if they can get to it. We'll find out in about seven hours time as that's when it's in for the smoke test.

I found some of the pics I was looking for on a US M3 M52 site. Now I understand how the airflow behind the manifolds work. Simple really but impossible to know until you see the inside flange faces.

Thanks again. :wink:
E46 B3 cabrio

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