Mercruiser 470 exhaust

[AeroNautical]

Mercruiser 470, I think, unknown year. Boat is a 1985 Wellcraft 192, had it in the water for the first time this week and it ran pretty well. After a little bit I noticed the temp rising on the gauge and put an IR thermometer to the engine and confirmed it was getting hot. I shut it off and took it home. Doing some research I saw one problem could be the water inlets in the exhaust elbow are clogged not allowing the water to exit through the exhaust. When I pulled the elbow off, they were indeed clogged, but there was also this steel plate which blocks the inlet anyway.
My question is, how do the cooling waters circulate with this plate on? I understand it's there because otherwise the antifreeze would be dumping into the exhaust and out in the lake. It seems like a counter-productive system. Any info available to help enlighten me?

 

[Bt Doctur]

does your elbow look like this 470 MIE
click to enlarge

 

[Bt Doctur]

That exaust system is no longer available asnd with no factory assistance I would be looking for a replacement motor or a v6 motor

 

[AeroNautical]

No, mine is a different style. I believe the part number on it is 76325 and I believe it is an A2 model. I found ones for sale online if I choose to get a replacement. I'm looking to see if the water inlet holes should actually be covered or if I should remove the plate?

 

[Bt Doctur]

 

[Bt Doctur]

on the front and rear of the manifold should be coolant hoses. There is a blockoff plate from the manifold to the elbow. The water leaving the heat exchanger goes out this elbow.from a hose fitting on the elbow

 

[AeroNautical]

Ok, thank you. So I will be keeping the plate on that blocks the 3 water jacket holes. And my elbow is the second picture posted.

 

[stonyloam]

Yeah If you have a 470, the hot water exiting the exchanger cools the exhaust. What you will want to do is change the impeller in the outdrive water pump. If any of the impeller fins are missing, look for them under the end caps of the heat exchanger.

 

[nola mike]

There was a 3 part gasket with a plate in the middle, not sure what you have. The replacements are just 1 paper/graphite gasket.