Exhaust flex pipe, to weld in place or not?!

[FNK]

I need to replace one of my exhaust flex pipe, I have the 2.8, so should I weld it in place or removing the whole thing is the only to go?

The three little nuts and the O2 sensor are very hard to reach!

[FNK]

Anyone done this?
Last year I tried to replace the driver side and I called quit.
This year the passenger side need replacement and I don't intend to pay 200$ like last year.

So far I know that I need to remove the CV heat shield, partially drop the sub frame.
This give access to the 2 lower nuts, but the top nut doesn't seem to be accessed this way, nor it the O2 sensor...

You guys have more hints?

[walky_talky20]

At the shop, we just weld those guys on the car. Entirely too much work to take it out and weld it. In addition, you have no reference as to length or position it should be welded once you cut it apart off the car. If you cut it off and weld it in on the car, everything positions itself for you so it can only end up perfect. It is tricky to weld the top bit, but for a good welder this should be no problem.

[FNK]

So that's like 1h~2h top. At 65$/h it's not too bad.

In this case, I might cut it and weld as much as I can myself (maybe just tack it) then let the garage finish it.

Great input, as always!

[Davect06607]

I attempted to weld these in place (novice welder) and couldn't get the top sealed up.
Eventually had to pull them off to weld them up tight.

[034Motorsport]

I wouldn't remove the flex pipes out of the exhaust, simply because you will be placing a lot of torque on the exhaust manifolds and you are far more likely to crack something. They are there to isolate exhaust movement from the motor.

[Mantis]

I wouldn't remove the flex pipes out of the exhaust, simply because you will be placing a lot of torque on the exhaust manifolds and you are far more likely to crack something. They are there to isolate exhaust movement from the motor.

Huh, I think he meant remove exhaust system from car to do the welding, not delete from system

I just did one on my wife's A4 1.8t, just loosened it a bit to get to the top section, so I guess I would say do it on the car BTW novice welder

[FNK]

At the shop, we just weld those guys on the car. Entirely too much work to take it out and weld it. In addition, you have no reference as to length or position it should be welded once you cut it apart off the car. If you cut it off and weld it in on the car, everything positions itself for you so it can only end up perfect. It is tricky to weld the top bit, but for a good welder this should be no problem.

The garage welded most of it but they couldn't reach the top section so they applied some high temp silicone over half an inch. So far (1600km since it's been done) it's silent. But will this hold in place?

[somebody5788]

It might, kinda dumb they couldn't reach. I've done both of mine and my dad welded them for me with no problem.

[FNK]

Well I will weld it if it leak... the silicone seems like a poor man solution, or a rip-off.

[BADB5A4]

I did mine last year. The top is tricky but not impossible. I used the braille method of feeding some line out and feeling out where the pipes joined and hit the trigger once in position. Basically just a bunch of tacks but it is at least a weld.

I have also heard of using JB Weld up there

[FNK]

I have a flux core wire (this wire doesn't need a welding gas) and the flux core tip is narrower than the gas tip, it should be easy. Time will tell IF the leak reappear!