Mud in exhaust manifold drain

[TBarCYa]

The boat is a 2008 Maxum 1800mx with the 3L mercruiser. Yesterday, I unhooked the two blue hoses to drain the block and exhaust manifold in case it got below freezing last nite (yes, I will winterize it before freezing temps are the norm) and while the block drained clear the exhaust manifold appeared to have some mud in it as the water came out pretty dark. I have dug the leg into the mud on occasion (the impeller is ok) so I'm pretty sure I know how the mud got into the system but I'm curious if this is a sign of something wrong or if it's normal for mud to collect in the exhaust manifold and not the block. Obviously, I don't want mud in either place so is there a way to flush the manifold?

I don't know if it's related, but at one point last season (it may have been the last time out) I forgot to reconnect the drain hoses and ran from the ramp to the sand bar (about 3 minutes) before realizing it. The temp gage never read higher than normal during this time. I pumped out the bilge and reconnected the hoses and when we were done at the sand bar we ran around for about an hour or more with no issues whatsoever. The temperature was fine, there was no water in the bilge and I checked the oil and it's not milky or otherwise looking bad. I didn't bury the leg during this trip.

Thanks.

 

[JustJason]

Re: Mud in exhaust manifold drain

your always going to get a little crap out of the hoses/drains. as time goes on you'll get more an more rust. The problem with the hoses is they can clog fairly easily. If you disconnect them and you DO NOT get a couple of gallons out of them then you need to disconnect the hoses from the block and poke in there with a screwdriver to get the mud/rust crap out.

as far as running the motor with the hoses disconnected for a few minutes.... you didn't hurt anything.