2000 Montana exhaust manifold bolts striped and fell out during normal driving I tapped new threads it worked good for a short while those have now also fallen Any ideas how tofix?

This is a serious problem that requires a robust solution, as exhaust leaks can damage your engine and are dangerous. Simply retapping the threads repeatedly isn't going to work long-term because the aluminum manifold material is likely weakened and the threads are being stripped. Here's a breakdown of how to approach this fix, progressing from simpler to more involved solutions:

1. Assess the Damage:

* Extent of Damage: How many bolt holes are stripped? Are they all on one side or spread out? This dictates the best approach.

* Manifold Condition: Is the manifold itself cracked or warped? If so, replacement is likely the only viable option.

* Head Condition: Inspect the cylinder head for damage to the threads. If the threads in the head are severely damaged, you'll need to consider more extensive repairs or replacement.

2. Repair Options (in order of preference):

* Helicoil Inserts (Recommended): These are the best solution for stripped threads in aluminum. They are threaded inserts that you install into the stripped holes, creating new, strong threads. This is a relatively straightforward repair if you have some mechanical aptitude and the right tools (a helicoil kit). Make sure you get the correct size helicoil for your bolt size.

* Timeserts: Similar to helicoils, timeserts are self-tapping inserts providing strong threads in damaged holes. They are a good alternative and sometimes preferred by mechanics.

* Welding (Advanced): If the holes are severely damaged or you're uncomfortable with helicoils/timeserts, a welder (preferably someone experienced with aluminum) can weld in threaded studs. This is a more involved solution and requires precision. It's only recommended as a last resort.

* Manifold Replacement (Last Resort): If multiple holes are stripped, the manifold is damaged, or the head is damaged, replacing the entire exhaust manifold is the most reliable solution. This is the most expensive option.

3. Important Considerations:

* Proper Torque: Once you've repaired the threads, use a torque wrench to tighten the bolts to the manufacturer's specified torque. Over-tightening will just strip the threads again.

* Anti-Seize: Always use anti-seize compound on the bolts before installation to prevent future seizing and corrosion.

* Exhaust Gasket: Replace the exhaust manifold gasket. A damaged gasket can lead to leaks even with good threads.

* Professional Help: If you're uncomfortable tackling this repair yourself, take your vehicle to a qualified mechanic. This is not a simple repair and could lead to further damage if done incorrectly.

In summary: Helicoils or Timeserts are your best bet for a lasting repair. Don't just keep retapping—you'll keep stripping the threads and ultimately damage the manifold or head beyond repair. Assess the damage carefully and choose the appropriate repair method. If unsure, seek professional help. A failing exhaust manifold is a safety hazard.