C63 Downpipe V Band Clamps leak, help needed

Jul 11, 2024 | 03:56 AM

Joey911

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Joined: Jan 2024

Posts: 25

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W205 C63 Sedan

C63 Downpipe V Band Clamps leak, help needed

Hey guys,

I've been battling with the V-band clamp leak issue for months now. Initially, we thought a bad downpipe caused the V-band to loosen (not the bolt loosening, but the V of the V-band spreading loose). However, after purchasing a reputable brand downpipe with 100 cell front and 100 cell rear, it still deformed the V-band. The next step is to install brand new V-band clamps.

Here's what I tried (with reused V-bands):

Buffed the V surface smooth
Cleaned the outer flange surface, free of debris
Applied copper anti-seize on the V so it could slide on evenly all the way around
Torqued it to 5 Nm wet (not sure of the factory spec, probably even lower in inch-pounds). Once it clicked, I used a rubber hammer on the opposite side and torqued it to 5 Nm again. Repeated until I couldn't tighten any further after tapping with the hammer.

I was able to seal it with no leak when idling or driving around town, but when driving with boost up (JB4 map 1), it would blow open, and I could hear the "blah blah blah" exhaust tone near reflecting surfaces.

I was wondering if anyone could pull up an installation guide on how to reinstall the catalytic converter on M177 engines, especially the part of V-band installation.

Thanks, Joey

Last edited by Joey911; Jul 11, 2024 at 05:31 AM.

Jul 15, 2024 | 02:18 AM