How to Weld Exhaust Pipe Under Car?

The exhaust pipe is an important component of a vehicle’s performance and functionality. A faulty exhaust damages your vehicle and costs extra money. What if I tell you how to repair cracked or rusted exhaust on your own and save money?

This blog post will show you how to weld exhaust pipes, including tools and materials. We will also discuss safety measures and different welding techniques you can use. Keep reading to the bottom to have all the knowledge and confidence to do the task like a pro.

Welding Gear You’ll Need for Exhaust Pipe

  1. Exhaust pipe welding machine
  2. Welding rod or wire
  3. Safety gear (helmet, gloves, welding shirt & pants)
  4. Cleaner supplies (sand Paper & wire Brush)
  5. Measure tools (tape and marker)
  6. Clamps
  7. Grinder
  8. Sealant 
  9. Ventilation system (if working indoors)

How to Weld Exhaust Pipe (Step-by-Step Process)

1: Preparation

Follow the steps below to prepare exhaust pipes for cleaner and stronger welds.

  • Cleaning the pipes: You need to make the welding surface free from contaminants. So clean it using a wire brush or sandpaper to remove any rust, debris, or dirt.
  • Measuring and cutting: Measure the pipe length used in the exhaust system and then cut them to the correct length using a grinder. Make sure that the ends of the pipes are straight and square.
  • Fitting the pipes: Check the alignment of pipes by putting them together using an exhaust clamp or a pipe wrench. Make any necessary adjustments to the alignment of the pipes before welding.
  • Marking the pipes: Mark the pipe’s welding area to help you align pipes during the welding process.
  • Preheating: It’s unnecessary, but it helps prevent pipes from cracking or warping during the welding process.

If you don’t want the hassle of cutting and measuring, clean the welding area and get to the action.

Related: Learn to Fix Exhaust Pipe without A Welder

2: Decide the Welding Technique

If you choose TIG welding, you will need to use a tungsten electrode to create an arc and heat the metal while feeding a filler metal into the joint. But remember, TIG welding is a precise method that requires a steady hand and a good understanding of the process.

If you go with MIG welding, you will need to use a wire feeder to feed the filler metal into the joint while creating an arc with the electrode. MIG welding is a faster and easier method than TIG welding and is more suitable for thicker materials and longer welds. I would recommend you use the MIG welder if you are a beginner.

Stick welding, also known as arc welding, uses a consumable electrode to create an arc and melt the metal. The electrode is coated with flux, creating a gas shield to protect the weld from the air. I would recommend using it only if you are a professional welder.

Related post: TIG vs MIG Welding

3: Welding Wire Selection

After determining the welding technique, choosing the right welding rod or wire is important. The selection will depend on the welding process and the type of metal used for the exhaust pipe.

For TIG welding, I recommend using ER70S-2 wire. For flux core welding, the E72T-11 welding wire is a good choice.

When using a MIG welder, a solid wire like ER70S-6 is suitable. It contains silicon and manganese and is coated with copper for an exceptional weld.

If you choose stick welding, you will use a metal rod. The 6011 electrodes are commonly used for producing excellent results.

4: Correctly Setting the Welding Machine

  • Adjust the polarity: If the pipe is made of mild steel, you will set the welder to DC (Direct Current) whether you use MIG or TIG welding. You’ll set the TIG welder to AC (Alternating Current) for welding stainless pipe. 
  • Set the amperage: You will set it according to the thickness of the pipe and the type of welder you are using. For example, if using a MIG welder, a setting of around 20-25 amps may be appropriate for welding a pipe that is 1/8 inch thick.
  • Set the gas flow: For MIG welding, set the gas flow to the appropriate level per the welder manual. For TIG welding, use a shielding gas such as argon to protect the weld from contamination.

Also, consider reading the welder’s manual to set the welder correctly.

Adjusting amperage on tig welder

5: Wear Protective Equipment

Once you complete the steps above, it’s time to take the necessary safety measures. I will advise you to wear welding helmets or lenses and gloves.

Pro Tip: Consider wearing a welding blanket to avoid welding arcs getting onto your body.

6: Tack Weld the Exhaust Pipes

Before welding, putting pipe ends together and clamping them to avoid injuries and burnt hands is crucial. C-clamps, which are inexpensive and widely available, can hold the pipe ends tightly and withstand the heat of the welding machine without damage.

However, fitting the clamps on the pipe ends can be challenging as adjustments must be made by hand for a precise fit before proceeding with the welding.

Steel exhaust pipe clamps

7: Time to Start Welding

Make sure that the electrode has a consistent distance from the pipe. The recommended distance from my side is 1-4mm if you use a TIG welder. When using MIG welding, the suggested distance between the electrode and pipe is ⅜ to ½ inches.

For stick welding, ⅛ inch is the optimum distance between the rod end and the weld piece. And with a flux core welder, it should be around 3/7″ to ½ inches.

8: The Final Round

  • Checking the leaks: Once you are done with the welding process, it’s time to check the leaks in the exhaust pipe. For that, you will start your car and let it sit idle. If you observe any defects, you will repair them by welding additional metal beads over the affected areas.
  • Cooling the pipe: Let it cool down slowly to prevent warping. It can be done using a heat-resistant blanket or leaving it to cool naturally in a shaded area.
  • Final inspection: Once the pipe has cooled, you should inspect the welds one more time to ensure they are smooth and free of defects.
  • Polishing the welds: Additionally, you can polish the welds to give them a smooth finish., you can use a wire brush or a grinding wheel to do so.

Safety Tips to Weld Exhaust Pipe

You are supposed to follow these safety precautions only if you don’t want the hassle of removing the exhaust pipe from the car.

  • Eliminate grease or oil: Before welding, clean any oil or grease residue to avoid incidents like fire. Often, high-temperature welding arcs make contact with the oil residues on the floor, escalating a massive fire.
  • Disconnect battery: When welding, you don’t have control over the welding arcs. Any of the arcs could damage the entire car computer. So, pull off the battery cables to avoid the connection between stray welding arcs and car electrical wiring.
  • Cover up the fuel tank: First, try to remove the exhaust pipe and weld it at a location away from the fuel tank. However, if it’s impossible to remove, consider covering the gas tanks with a welding blanket.
  • Fume extractor: Metal produces toxic fumes when welding, and accidentally Inhaling such fumes could pose serious health threats. To prevent fume from getting into you, try to weld in a well-ventilated place and use a fume extractor to avoid serious health problems.

However, if a fumes extractor is heavy on your pocket, consider buying one or two small fans, as using these fans correctly blows away from your face.


How hard is it to weld the exhaust pipe?

Welding an exhaust pipe can be tricky, but you can take specific steps to ensure it doesn’t seem too difficult. The first one is practice. The more you practice, the easier it becomes for you to do the job.

The second one is the welding you opt for. It is a collective opinion that TIG welding is the best for welding exhaust pipes, but MIG and stick welding can also be used.

What is the best rod for weld exhaust pipe?

The best welding rod is 309L. It’s a stainless steel rod specifically designed for welding exhaust systems, as it can withstand high temperatures and resist corrosion.

Whats the best amperage range for welding exhaust pipe?

It depends on the thickness of the pipe and the welding technique used. Typically, MIG welding requires around 100-150 amps, while TIG welding requires around 60-100 amps.

Is cracked exhuast weldable?

It is possible to weld a cracked exhaust. However, it is important to note that welding a cracked exhaust pipe may not always be the best option. Cracks may indicate deeper structural issues, and welding may only serve as a temporary fix.

Therefore, It is important to thoroughly inspect and determine the extent of the damage before attempting to weld it.

How long does welding an exhaust pipe take?

Usually, it does not take more than twenty minutes to weld an exhaust pipe, but the time may vary with the type of welding you are using and your practice.

If you have a great skill set and a lot of practice to go with it, then you may finish welding the exhaust pipe in less than twenty minutes.

Besides, it also varies with the conditions in the exhaust. Most of the time, the conditions are less than ideal, so it will take longer than twenty minutes to weld it.

Wrap Up

I hope this post has provided you with the necessary information and guidance about how to weld exhaust pipes. Following the steps above, you can weld an exhaust pipe like a pro and save money.

Remember that practice is key to mastering your skills; the more you practice, the better you will become. Don’t forget to follow proper safety measures before starting the welding process. Happy Welding!

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Dave Walker is a skilled welder and passionate blogger. With years of experience in welding, he has honed his craft and developed a deep understanding of the trade. In his blog, he shares his experiences, insights, and tips on welding, offering a valuable resource for fellow welders and those interested in the field. He is dedicated to promoting the importance of welding and its applications in various industries.