Changing out the exhaust manifold on a turbo DSM can be an exercise in frustration and learning. Here are some tips to make it easier.
- The studs break. 90-94 cars do it more, but the 95-99's break studs, too. Have extra studs on hand before you start your work, especially if that's your only car.
- When the studs break, they sometimes break off IN the head. You can attempt to use an extractor, but BE CAREFUL -- the head is aluminum and repairing a too-large hole can be a major pain. If the extraction is not going well, consider removing the head and taking it to a machine shop. You may end up having to use a Heli-Coil to reconstruct the threads. The Heli-Coil is a perfectly fine way to go, and ends up being stronger than the original threads.
- When you put the manifold back on the car, we suggest using standard grade metric nuts, NOT the OEM high-grade stuff. Use a normal split lock washer and one flat washer. This will hold the manifold on, but will also allow a little more strech to avoid popping the studs. Tighten the fasteners down to 18-22 ft-lbs. Use a torque wrench.
- The turbo is held to the manifold by three bolts and one stud. This means you MUST take the manifold off to remove the turbo from the car. If you ever plan to take the turbo off again, you can make things easier on yourself by getting a fourth bolt at the local dealer (or from us) and installing that instead of the stud. That way you can remove the turbo without taking the manifold off.
There are compromises to removing the stud. The turbo will have a greater tendency to shake its bolts loose without the stud holding it still. Tym at Buschur Racing suggests torquing the nuts to 50 ft.-lbs., then driving the car until it is warm, then re-torquing again to 50 ft.-lbs.
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