How to remove exhaust manifold bolts

Updated February 21, 2017

The exhaust manifolds of your car are what takes the high heat gasses from your engine and expels them to help keep your engine cool and running at its peak performance. Stock exhaust manifolds are made of cast iron which, while long lasting, does not do the job of getting heat out as well as a performance manifold (which may be ceramic lined or steel coated). One of the most difficult jobs on a car is how to remove exhaust manifold bolts. The removal itself is not difficult. However, learning a few tricks to do it without breaking the bolts and with a minimum of effort is necessary to keeping this task moderately easy.

Attach the red spray straw to the nozzle of the PB blaster, and spray the exhaust manifold bolts, starting from the bottom and working all the way around the bolt head. When you are done spraying each bolt head, tap the bolt with a box wrench to send vibrations through it to help the PB work its way into the threads.

Select a box wrench that fits the nut head and place the wrench on the nut. If you do not have threads from the bolt exposed, but a flat bolt head, use a stud puller instead of a box wrench. If you are using a stud puller, skip the rest of the steps and begin working the stud puller in a counter-clockwise fashion to loosen the bolt.

Spin 1 locknut onto the exposed threads, but do so with the cast lock of the nut facing out. You are putting the locknut on backwards. Put the other locknut on in the normal fashion. Make sure they are tight together.

Attach a socket wrench to the top locknut. Make sure the handle of the socket wrench is lined up with the handle of the box wrench you put on the bolt in Step 2.

Grab both wrench handles at the same time and pull in a counter-clockwise direction. If the bolt does not break free immediately, tap the handle of the box wrench lightly with a hammer in the same direction, repeat this until the bolt breaks free.


It is not unusual, due to the high temperatures that the bolts are subjected to during their lifetime, for one to invariably break. Have a drill and bit on hand to drill out any broken bolts and a rethreading bit.


Never try to remove the exhaust manifold bolts on a hot engine, the extreme temperatures of the exhaust manifold can cause the PB Blaster to catch fire when applied; always allow the engine to completely cool before beginning work.

Things You'll Need

  • PB Blaster Penetrating Catalyst Spray
  • Box wrench
  • (2) locknuts
  • Socket set
  • Stud puller
  • Hammer
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About the Author

Cassandra Tribe has worked in the construction field for over 17 years and has experience in a variety of mechanical, scientific, automotive and mathematical forms. She has been writing and editing for over 10 years. Her areas of interest include culture and society, automotive, computers, business, the Internet, science and structural engineering and implementation.