1969 318m overheating

I have a 1969 correct craft s

I have a 1969 correct craft ski boat with a chrysler 318m motor the engine runs between
190-200 degrees. it has a new water pump I'm not sure as to what is the difference between a fresh water system and a raw water system.Ive checked
for blockage in all the lines but water is flowing thru all the lines. I was told water temp for this engine should be around 165 degrees.

Don

"Don, you don't mention

"Don, you don't mention if the engine has a thermostat, but if it's original and has a raw water cooling system (outside water is pumped through the manifolds and engine, rather than through a heat exchanger), the water jackets are probably filled with sediment. It's not uncommon to find jackets half-filled or more with packed sediment.

The sediment prevents water from flowing in the lower block and will contribute to a hot running engine. This would be a slow buildup over time, however, so if the engine has suddenly started running 20 or 30 degrees hotter then the immediate problem may be elsewhere.

If everything else checks out, drain the block (if possible) then pop off a freeze plug on the low side of the engine block. If muck doesn't come flowing out, stick a coat hanger wire in there and scrape around. Catch any crud in a pan so it doesn't go into the bilge. If you hit a crud gusher, you'll need to do the same thing to all the freeze plugs. Use a garden hose to flush the jackets out until the water runs clear. Use brass replacement freeze plugs and sealant.

"

sorry it took so long to get

sorry it took so long to get back here I had to leave on business. I do have a heat exchanger.
I pop a freeze plug out but did'nt find any sedamint.