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Topic: 2007 Seneca Duramax: Downpipe to Cat pipe joint repair (Read 164 times) previous topic - next topic
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2007 Seneca Duramax: Downpipe to Cat pipe joint repair

I have a 2007 Seneca on a 2006 C5500 chassis with a LBZ Duramax. I noticed exhaust smell in the cabin and traced it down to the joint between the turbo downpipe and catalytic converter exhaust pipe:
X   X

OEM replacement parts listed for about $500 before shipping  :o
Here's what I did -
Parts purchased:
Walker 41646 flared exhaust pipe ($20 on Amazon)
Squirrelly 3" x 4" stainless flex exhaust pipe ($23 on Amazon)
Grand Rock v-band clamp GRVB-384G ($26 including shipping from xtremediesel.com)
Felpro 61287 catalytic converter gasket ($8 at NAPA)

Assembly:
Cut 1.75" off Walker piece:
X

Cut 5.5" off cracked end of exhaust pipe:
X

Weld-r-up and test fit to downpipe:
X   X

Reinstall and check clearance:
X   X

So, for about $75 in parts and a little of my time, I'm hoping the flex joint with relieve the stress and keep it from cracking. I should be no worse off than if I had implemented the oem parts except that I have extra money in my pocket for other things. I hope this helps someone else like this site has helped me! Your mileage may vary...




Re: 2007 Seneca Duramax: Downpipe to Cat pipe joint repair

Reply #1
I have a brand new item 3 in the drawing. I have no need for it.
Your fix looks good.

Re: 2007 Seneca Duramax: Downpipe to Cat pipe joint repair

Reply #2
I've broken pipe #3 in the diagram and the flange from the front of the catalytic converter not pictured.  Now we have broken the long pipe behind the cat.  Seems like no matter how we add hangers to the exhaust, it's always under strain and breaks. 

Re: 2007 Seneca Duramax: Downpipe to Cat pipe joint repair

Reply #3
I haven't but I'm not surprised given how thin pipe #3 was.