How to Permanently Attach Exhaust Flex Pipe No Clamps

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Hi, I'm Mike from 1A Auto. I hope this how-to video helps you out, and next time you need parts for your vehicle, think of 1AAuto.com. Thanks.

In this video, we're going to show you how to install a universal flex pipe on this 2007 Audi A4. These pipes can often be attached with clamps, but we went ahead and took the extra steps to show you how to permanently attach one. You'll need a new flex pipe from 1AAuto.com, tape measure, market or a paint pen, soap stone, anything to mark metal, a reciprocating saw, and vernier calipers may be useful. You might need a wrench if you need to remove the center exhaust clamp—ours is a 17mm, a rust removal tool, such as a rust disk, wire wheel, or wire brush, a welder with all the associated tools such as a welding mask and thick gloves, and jack and jack stands.

The flex pipe coming off of the down pipe from the turbo on our Audi is torn, broken through. It's leaking exhaust. This can cause noxious fumes inside the vehicle, failed inspection, obviously you're going to get some bad emissions out of here, and a lot of unwanted noise.

We're going to replace the flex pipe rather than the entire down pipe, which includes the cats on this vehicle with a universal flex joint from 1A Auto. While we do sell this and will fit our vehicle this is not a direct fit piece. It's going to have to be cut, fit, and welded.

Before attempting any kind of job like this, be sure that you have the proper tools and safety equipment, as well as the training and knowledge to do the job right and safely. After you know the measurement of your replacement flex pipe, raise and support your vehicle with a paint pen, grease pen, soap stone, or something to mark the steel. We're going to use a reciprocating saw with a nice fresh blade on it. Cut it just behind this flange on the flex pipe here. Be careful that you use a short blade, don't damage the heat shielding or cut over into the transmission. Always use proper safety equipment.

Now we'll cut the other end of the pipe. Measure the inside diameter of the pipe with vernier calipers, spread them out, rotate them until you find the largest point in the pipe. See that ours is 2.18 on the inside, 2.29 on the outside. You can either convert the number on the calipers into a fractional number, or you can use a measuring tape and swing it along the pipe.

The largest measurement is going to be the outside diameter, or you can press the corner in underneath, do the same thing to find the largest number. Get your ID, inside diameter and OD, outside diameter of the pipe. Order your new pipe to slide over or inside so you can use a clamp or get a better weld.

We're going to loosen our clamp with a 17mm wrench. Remove this part of our pipe so we can weld the flex joint in, make it easier to fit this. Since we can't remove the down pipe from this vehicle, we're going to use this rust disk, you can also use a wire wheel, a wire disk, or a wire brush or file just to remove the rust on the edge here. Give us a nice clean surface to weld too.

Install your flex pipe, trying to keep it as inline with the joint as you can. While the pipe is designed to flex, any pressure that we take off of it in the normal position is going to help ensure the longevity, make sure that it's not contacting the vehicle anywhere and that you have good clean metal coming up to where you're going to weld.

Once you’re sure your pipe is where you want it to be, through your ground on, set your welder appropriately, and start a couple of tacks. Once you've started your tacks, make sure that everything's still where you want it to be and it's sealing the pipe. We had to do a little more cutting and trimming to make this end line up. I marked it to where it needed to align to the joint, cut it, cleaned it the same way we cleaned the other side.

Now we're going to hold it together and throw a few more tacks on. After you've completed welding in your flex pipe, we have to move our clamp at the center of the exhaust because the way it's clocked isn't going to clear because of the way our pipe is welded now. Rotate it to a place where it won't interfere. Once it's clocked to a place where it won't hit and make any noise, go ahead and tighten down your clamps with a 17mm socket and ratchet.

Thanks for tuning in. We hope this video helped you out. Next time you need parts for your car, please visit 1AAuto.com. Also check out our other helpful how-to and diagnosis videos.