i did a few pics today as i was looking into the big hose going into the thermostat and the front edge of the exhaust risers ...primarily port side of each engine
for 2 engines with 860 hours of fresh water
these are gm 350 omc build engines
pulling plugs tomorrow and look inside before new plugs go in

they look darn good
i still have to scope the stbd engine stbd aft exhaust drain port to see up inside,

That's pretty cool...

looks more like growth than rust! which is good !
thanks for sharing !

changed 11 of 16 spark plugs this afternoon
old body had had enough and i broke a plug when it dropped from hand to the bottom of the bilge bouncing on stuff
but some of the pics show a good bit of burnt oil build up on a 4 stbd engine
vale looked good, so i assume oil is from rings
it does a have a few small pits in the chamber walls but cross hatch is still very visible
i am wondering what i could run to break off or burn off the oil residue

sorry pics are not professional quality
its hard running borescope, hanging upside down and trying to operate the end for focus
but 860 hrs i thought so far they engine inside look darn good
still have port engine odd cylinders






to do tomorrow

Wow, I think those are pretty good views. What borescope are you using? The one I have is a POS. I have heard of ones you attach to your phone, I was thinking of getting one of those.
On another note, the inside of the water passages look pretty good. Would it be worth flushing out marine blocks with a rust remover or does that make things worse? Just asking.