Boat overheating mercrusier 350?

[tony45power]

i have a 1982 searay sundancer. i just had a new engine installed new water pump new pump in the outdrive. the manifold and risers are about 2 years old. the engine overheats in the water and with earmuffs. with the boat in a boat slip i puller the water hose near the transoms and the outdrive is pushing water through it. I took the thermostat out and it still overheats. the gauge is fine. Is there a diagram that shows the water flow? so i can check the water flow.

[pistnbroke]

how do you know its over heating ?? are you looking at a gauge? if so is the sender in the engine compatible with the gauge .....best way is to take sender out of engine and put in an electric kettle and boil.....then you will know where 100deg is on your gauge ( oops sorry you are a yank 212f )

Water in by pulling hose does not mean water out ? have you checked that ?

[Frosty]

I have to agree --Damn it --you have to be sure it is overheating first.

[tony45power]

yes its overheating, i check the engine with a infrared laser. once the engine got up to 240 it pinned the guage and then i lost power in the engine, even burnt the paint off the manifolds.

[tony45power]

i hooked up a water hose into my t stat housing and now the engine runs cool. But! the lowerunit is pumping water also!sooo im thinking the water pump on the engine is bad now.

also now the engine is running cool why does 1 riser get super hot and the other riser is cool?

I took the riser off and its very clean inside. i tested the water jackets and they are draining fine. maybe the manifold is bad? the gaskets on my riser only were letting water through 2 jackets not all 4? there a reason for that?

[Frosty]

Ok so this is a raw water cooled engine? Have you checked the impellor in the pump? yes it may be pumping water but obviously not enough if you stick the supply into the thermostat housing and it runs cool.