vFAQ : Removing/Installing Exhaust Manifold Studs
  1. The first ( most important) step is to soak the nuts with penetrating oil (Kroil...etc) before you start to remove them. The studs on this car were never removed before (125k miles on the car) and over a period of a week or two we soaked the studs about 6 times. This will really help in the removal of the nuts. If you can give the nuts/studs a few applications of the penetrating oil and allow it to work in over a couple days you will see better results.

    Depending on the type of penetrating oil you use the recommended penetration time varies. Make sure you allow enough time for it to do it's job, the longer you let it soak...the better.

   
  1. When all of the nuts were removed, we had three studs that snapped off at the manifold flange. We were lucky because they broke at a point where there was enough thread left on two of the studs that allowed us to use the "double nut" method to remove those two studs.

    If you have enough threaded stud to get two nuts on you will need to get two M8x1.25 NON-locking nuts. We recommend not using nuts that you plan on using with your new studs, the double nutting process may damage the nuts.

  • Thread both nuts onto the broken stud
  • Hold the rear nut steady with a wrench, with another wrench tighten down the front nut onto the rear nut. These nuts will now be locked onto the stud.
   
  • Turn the rear nut counterclockwise as if you were just removing the nut. Be very careful to make sure that you are supporting the stud while you are applying torque to remove it. You do not want to snap the stud off again, if you do you will have to use another method to extract them. Both nuts should be turning together (along with the stud). If the nuts are turning off of the stud you will need to perform the previous step again to secure the nuts onto the stud.
   
  • The one stud that didn't have enough threads on it to thread two nuts on it prompted us to get a small pipe wrench out. A pipe wrench works nicely for this since you can get the jaws to bite down on the length of the stud that is protruding from the head. Again, we were lucky and this stud turned right out.

    This method is a bit easier than using the double nut method, especially if you haven't done that before. It is also a bit safer as you will be applying the load on the unthreaded portion of the stud as well. At this point you will only have to worry about the metal end of the stud breaking (metal end = portion of the stud that is threaded into the head), instead of both the metal end and external threaded portion as you do for the double nutted method.

   
  1. All of the studs are removed. Now it is time to clean up that messy exhaust leak, clean the gasket surface with some Scotch-brite and inspect the threads to see if any are damaged.
   
 
  1. Visually inspect all of the threads. If they are damaged, follow steps below to fix them.

    a. Outer threads are damaged - use a Helicoil to repair

    b. Debris from corroded studs remains in threads - chase the threads with an M8 or M10 tap(depending on what size studs they are). Be careful to follow the old thread profile, the tap should move relatively smoothly when cleaning up threads; if it takes any effort to turn the tap wrench, back the tap out and make sure you are not cross threading.
    If the debris is loose you can try to blow it out with air. Be sure to wear safety glasses, rusty steel particles are no fun when they get in your eyes.

    c. Threads are stripped and unusable - the easiest thing to do here is install a Helicoil to replace the threads. See our Helicoil vFAQ for instructions.
   
  1. Install studs
    a. The head should offer some resistance when installing the studs as the internal threads are meant to be an interference fit with the studs.

    b. Place two spare nuts (ones you will not be using) on the long end of the stud, use two wrenches to tighten them down onto each other.

    c. Start threading the stud into the head by hand, when you reach the point that you can't turn it by hand get a wrench. This is when you will really appreciate a ratcheting wrench. Turn the studs down into the head. DO NOT turn them in too far, once you reach the end of the threads STOP!
   
  1. Place anti-seise on the studs, hang the gasket and then place the exhaust manifold on the studs.
   
  1. Tighten down the nuts onto your new stainless studs. Use stock torque specs (18-22 ft. lbs).
   
  1. Tighten down the turbo bolts and torque them to stock specs (40-47 ft lbs).