Jet Ski Exhaust Repair

[Don52]

The exhaust of a Jet Ski is a casting with an inner pipe and an outer pipe. The exhaust goes through the inner pipe and water goes between the inner and outer pipe. During the casting process a sand core is necessary to form the cavity between the inner and outer pipes. The casting is designed with holes on the outside to support the core and to drain the core sand. After the casting is complete caps are welded on to cover the holes. The material of the caps is more susceptible to corrosion than the casting, so they act as a sacrificial anode and corrode first. Attached are some pictures of the process that I used to replace the caps on two exhaust manifolds.

1. Manifold with damaged cap

2. Close up of damaged cap

3. Damaged cap ground off

4. Paint ground off

5. making new cap

[Don52]

The last picture shows the exhaust manifold painted and installed in the jet ski.

6. New cap welded in

7. Two manifolds done

8. Manifold painted and installed


-Don

[MAC702]

Very nice work.

What material is the new cap? Keeps sacrificial anode properties?

Any special reason for lathe parting instead of bandsaw, or just because?

[ryanjones2150]

For me, I’d use any excuse I could find to part something in the lathe over the band saw.

[Don52]

What material is the new cap?

6061-T6 Aluminum

Was the material selected to keep sacrificial anode properties?

No, it was what I had on hand.

Any special reason for lathe parting instead of bandsaw, or just because?

Using the lathe I could square up the bar, ensure a parallel cut and chamfer the edge.

[Don52]

For me, I’d use any excuse I could find to part something in the lathe over the band saw.

I agree. If you have a nice tight lathe it is easy to use the parting tool.

-Don

[MAC702]

Good point about the chamfer and squareness. I'm also assuming much less chance of joint contamination, too.

[Aeronca41]

For me, I’d use any excuse I could find to part something in the lathe over the band saw.

Yep!

[Aeronca41]

Beautiful work, as usual, Don!