Thanks guys. Wingless, your procerdure...

[old_timer]

Thanks guys.  Wingless, your procerdure sounds VERY impressive.   I looked at the Perko deal, it is a little scary in that it is plastic, and who knows when that will fail.  Do you flush the generator also?  This boat only has 122 hrs on it, although it is 8 YR. old.  The previous owner claims an exhaust/riser redo last year.  I am doing survey this Wed.  I guess the only external indication of a problem is to watch the temp.  Right?

[wingless]

YW

The quick check for the exhaust is that it should be possible to continuously hand hold the parts while the engine is up to temperature while operating.

The engine coolant temperature gauge will not show any issues w/ exhaust deterioration.

The best option is to disassemble one joint and perform a visual inspection of the internal raw water passages for corrosion and inspect the cleaned mating surfaces for sufficient SOLID wall thickness. Be aware of color variations where the casting appears flat but is no longer solid.

Note that if disassembling, then a replacement gasket is required.

Note that the exhaust is frequently replaced w/ aftermarket parts to save cost. I always used original OEM Mercruiser parts. The embossed markings will show the manufacturer for those parts.

Also check the raw water hoses. It should be possible to hand squeeze the hoses, like in a car engine, w/o having a crunchy or hard feel. Especially check the one feeding the bottom of the exhaust manifold.

A very good quick check is for rust staining on the side of the hull, where the stationary / idle raw water and exhaust gas exits.