Exhaust Flange Bolts: 6 Steps to Remove Them

Removing exhaust flange bolts requires the right tools, technique, and patience, especially when dealing with rusted or corroded bolts. 

Whether you’re seeking professional help or just doing it yourself, it’s important to get to know the nitty-gritty of exhaust flange bolts.

This guide explains the working principle of exhaust flange bolts, their sizes, and step-by-step instructions on how to remove them efficiently.

Read on to learn more.

Working Principle of Exhaust Flange Bolts

Exhaust flange bolts secure the exhaust system components together, ensuring a tight seal between the exhaust manifold, catalytic converter, and muffler. 

These bolts withstand extreme heat and vibrations, making them prone to rust and corrosion over time.

Size of Exhaust Flange Bolts

The size of exhaust flange bolts varies by vehicle make and model. Common sizes range from M8 to M12, with length and thread pitch depending on the flange thickness and exhaust system design. Always check manufacturer specifications before purchasing replacements.

How to Remove Exhaust Flange Bolts

Step 1: Loosen Exhaust Bolts with Penetrating Oil

Spray a penetrating oil like WD-40 or PB Blaster on the exhaust flange bolts and let it soak for at least 15 minutes. This helps break down rust and corrosion, making removal easier.

Step 2: Use the Right Socket and Wrench

Select the correct socket size, usually 12mm or 14mm, and attach it to a ratchet or breaker bar. Turn counterclockwise to loosen the bolts.

Step 3: Apply Heat to Stubborn Bolts

If the bolts are rusted and won’t budge, use a propane torch or heat gun to heat the area for 1-2 minutes. The expansion from heat can help break the rust bond.

Step 4: Use an Impact Wrench or Bolt Extractor

For bolts that are stripped or heavily rusted, an impact wrench or bolt extractor set can provide extra torque for removal.

Step 5: Detach a One-Bolt Style Exhaust Flange

If your exhaust flange has a one-bolt design, loosen the single bolt while supporting the exhaust pipe to prevent sudden drops.

Step 6: Tighten Exhaust Flange Bolts During Reinstallation

When replacing the exhaust flange, use new bolts of the correct grade (typically Grade 8 or stainless steel). Tighten them evenly to avoid leaks.

FAQs About Exhaust Flange Bolts

1. What grade bolts are used for exhaust flanges?
   • Exhaust flange bolts are typically Grade 8 or stainless steel due to their strength and resistance to heat and corrosion.
2. What bolts should be used on an exhaust?
   • High-temperature, corrosion-resistant bolts such as stainless steel or zinc-coated steel are ideal for exhaust applications.
3. How do you remove rusted exhaust bolts?
   • Apply penetrating oil, use heat, and try an impact wrench or bolt extractor for heavily rusted bolts.
4. Can I reuse exhaust flange bolts?
   • It’s best to replace old bolts with new ones to prevent future rusting and ensure a secure fit.
5. How to replace an exhaust flange?
   • Remove the old flange, clean the mating surfaces, install a new gasket, and secure it with new bolts tightened evenly.

This step-by-step guide ensures a smoother removal process while preventing damage to your exhaust system.

For more bolt types, check out the CNRL product catalog today!