Exhaust leak after downpipe install

[OlyS6]

Darn it!

After thinking my self install of my APR downpipes went well, it turns out I've got an exhaust leak where the driver's side downpipe meets the midpipe (coming out of the end of the sleeve clamp that holds the downpipe and midpipe together).

I had smelled some faint exhaust smell in the cabin since the install, and finally diagnosed the issue by using the blower function on my shopvac and hooking it to one of the tailpipes, and sealing off the other tailpipes (engine cold and off of course). There was pretty significant hissing around this connection, while all other connections are air tight.

I messed with the pipes and sleeve collar several times, and with tightening the heck out of the clamp, the leak is still there. On closer inspection, the end of the downpipe isn't perfectly circular- one side is flattened a bit.

Any suggestions on a different clamp or heat resistant gasket or wrap that I can try? Other thoughts?

[DGVR6]

You can use muffler sealant .. apr should've included that with the kit for the clamps imo

https://www.permatex.com/products/sp...ilpipe-sealer/

[OlyS6]

You can use muffler sealant .. apr should've included that with the kit for the clamps imo

https://www.permatex.com/products/sp...ilpipe-sealer/

Thanks! I used it last night on both clamps between the downpipes and midpipes- seems to be working well. Is that what you used as well? I thought the clamps would fit snugly on their own without an exhaust leak, but in my case, I couldn't make it work without the permatex. Seems to be good stuff!

[DGVR6]

Thanks! I used it last night on both clamps between the downpipes and midpipes- seems to be working well. Is that what you used as well? I thought the clamps would fit snugly on their own without an exhaust leak, but in my case, I couldn't make it work without the permatex. Seems to be good stuff!

Yea, I seal up whatever exhaust connections that doesn't require a gasket with that paste

[kpriv]

Oly - I was going to check in how that worked as I'm looking to do my install next week. Good to hear.

On a related note -- did either of you guys used anti-seize on any on the bolts/O2 sensors or gasket maker on the downpipes?


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[DGVR6]

Oly - I was going to check in how that worked as I'm looking to do my install next week. Good to hear.

On a related note -- did either of you guys used anti-seize on any on the bolts/O2 sensors or gasket maker on the downpipes?


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I have a custom downpipe, so I used a regular exhaust gasket to mate the milltek. The o2 sensor and bolts I left as is, even reused the turbo flange nuts, just don't over tighten

[OlyS6]

Oly - I was going to check in how that worked as I'm looking to do my install next week. Good to hear.

On a related note -- did either of you guys used anti-seize on any on the bolts/O2 sensors or gasket maker on the downpipes?


Sent from my iPhone using Audizine

So the permatex muffler/tailpipe sealant worked great on the sleeve clamps connecting the downpipes to the midpipes. It's rated up to 2000 degrees, so hopefully will hold up over time.

I did not use any ant-seize or any other products on any of the other connections. A repeat exhaust leak test (using the blower function on a shop vac connected to one of the tailpipes and sealing up the other tailpipes) did not demonstrate any evidence of a leak anywhere else.

I do have a bit of concern that the O2 sensors relocated beneath the car are exposed to the elements now. I didn't wrap them with anything, as they have a plastic sheath around the bit of exposed cable, but I can imagine that becoming a 'weak link' over time.

On another note, for the O2 spacers, I used the smallest flow restrictors that came with them. Although there is no check engine light, I did notice yesterday that while running VCDS diagnostics, there was a log for a 'too lean' measurement of the rear O2 sensors after a few hundred miles. I believe this means that it thinks the cats are now 'too efficient'. I reset the code and will check periodically to see how much driving it takes to repeat this error. If it's a frequent occurence, I'll likely switch to the middle flow restrictor and see how that goes.