exhaust manifold leak potential?

[Pete G]

I've been going through the M25 engine in my MK1.  After a good degreasing, I was concerned about the exhaust manifold connection.  Specifically, the green area, but also the rust shows me there's probably a leak.  This is a fresh water boat (Great Lakes).  The flange doesn't seem to make a good connection, and I'm wondering if it could be installed incorrectly.  I had to remove the heat exchanger to repair the mounting bracket, and I have easy(ish) access now.  Any advice?   

[Dave Spencer]

Pete,
The "green area" is the gasket between the flange and the engine. No cause for alarm there. If there was any kind of a leak, it would be very obvious with copious smoke and significant staining of the area in the picture. Rust is not an indication of an exhaust leak. That connection looks good to me.

[Pete G]

Thanks, Dave

[KWKloeber]

Observing while running her should confirm an exhaust leak or a diaper underneath confirm a coolant leak past the gasket.

It's one of the best condition exhaust flange/exhaust manifold I've seen pictures of so IIWMB I'd not suspect anything improper from simply that visual. See the gasket below.

If you're referring to the slight area of rust right at the edge of the exhaust manifold I'd think it is just that, rust working underneath the paint at the edge between painted/unpainted (machined) face of the manifold.  Again i don't believe that visual is sufficient to ID a leak.  No more than the few rust spots elsewhere indicate a pinhole in the manifold.

Note that under most, if not all, of the older engines' Universal copper-bronze paint is Kubota factory green.