How to Install Marine Exhaust Manifold Gaskets

When you change the exhaust manifold, change the gasket.

In a perfect world, an exhaust manifold would last forever. As nice as that would be, much of your boat's exhaust system will need to be replaced every few years, or your exhaust system will cause hot spots and "terminal damage" to your boat's engine. This means that every few years you'll have to replace the exhaust manifold gaskets as well.

Things You'll Need

• Gasket kit
• Wrench
• Torque wrench

Instructions

1. Be certain you have the correct gaskets for the exhaust system for your motor. Identify the gasket set by the motor model number.

2. Use a wrench to remove the bolts that hold the exhaust manifold in place. Stash the bolts in a shirt pocket so they don't become misplaced.

3. Inspect the gaskets for the exhaust manifold. Hold the gasket in place to check its general fit--ensure the holes are in the correct locations, and that the holes are the right size and oriented properly. Inspect the general condition of the gaskets. They should be free of tears or other major imperfections.

4. Hang a gasket on the studs that extend from the engine block where the exhaust manifold was bolted and slide it back against the block. If the block is painted, there's no need to remove the paint.

5. Set the exhaust manifold back in place and reinstall the bolts to hold it in place. Torque the bolts to the manufacturer's recommended torque. Performance Product Technologies, an exhaust system manufacturer, recommends tightening the bolts to 10 foot-pounds in a "uniform sequence," then tightening the bolts to 25 foot pounds in the same sequence. After that, tighten the bolts to the recommended torque.

Tips & Warnings

• Check the torque on the manifold bolts after running the engine for 30 minutes, then check the torque again after the first 20 hours of engine operation.

References

• BoatUS: Exhaust Manifolds
• Performance Product Technologies: Marine Exhaust Tips