Photo of Blocked Exhaust

[Administrator]

Here's a great photo of a blocked exhaust provided by Tiffany Miller:

You can easily understand why the engine wouldn't run...

[bob.medico]

What causes blocked exhaust

I am wondering what causes this condition in the photo. Is it caused by running at low temps?

[Don Moyer]

Bob,

We have a call in to the owner of this particular boat for more details on the conditions that led up to this blockage.

In general, scaling most often builds up at the point where water enters the hot section of the exhaust system. The sharp temperature increase at that point apparently causes salt and other minerals (iron, etc.) to precipitate out of the engine cooling water and collect within the hot section. Since this encrustation is in the aft end of the manifold itself, it's not clear to me where the water would have originated to cause this particular blockage.

Best regards,
Don

[redwitch]

blocked exhust manifold

in the picture of the blocked exhust I see some kind of lower drain (small pipe) what is it?

[Don Moyer]

Redwitch,

I don't know how this happened, but the photo is actually upside-down. What appears to be a drain on the bottom of the photo is actually the standard early model water outlet on the top (rear) of the manifold.

We'll fix the photo.

Don