There is a lot of advise for Universal overheating, some good some just a waste of time. You need to understand the system. There are two distinct systems for cooling the engine, The fresh water system and the raw water system. Heat from the combustion chamber as well as the exhaust manifold is transferred to the fresh water cooling system. Heat is then transferred to the raw water cooling system by way of the heat exchanger. The heated raw water is then discharged through the exhaust which is why you see water coming out of the exhaust. It is imparative that the raw water system is working correctly, through hole inlet not clogged, all hoses not clogged or collapsed (you won't be able to tell from the outside), the impeller is in good shape, the heat exchanger is clean and clear of obstruction. The fresh water system must have absoutely no leaks, a pressure test and close inspection should tell you. The engine temperature should be no more than 160 to 180 degree's at moderate speed. If you push it to full throttle for a long period of time it is common to reach or exceed 200 degree's. It is not advisable to operate at this temperature as boil over and engine damage can occure. I have learned that the orinal heat exchanger for some universal eninge was underdesigned. A larger heat exchanger is available at lencocoolers.com for a reasonable price. By the way I am currenlty experimenting with adding an electrically driven pump in parallel with the mechanical raw water pump. One issue with that is wiring it so it will never operate when the engine is not running as it will flood the cylenders and prevet the engine from turning over and could cause damage if the water isn't first evacuated.
Recommendations:
1. Flush the through hule inlet backward or remove the hose momentarily open the valve and force rod or heavy wire through it and close the valve.
2. Install a new impeller
3. Clean and inspect the heat exchanger.
4. Disconnect the raw water discharge from where it enters the exhaust system, using a small containern start the engine (no more than a couple of minutes) and time how long it takes to fill to 1 or 2 gallons. I should be able to produce at least 3 - 5 gallons a minute at medium throttle.
5. Be sure the fresh water system is full, the my reservior is a clear container located in the port cockpit locker (it has a full line). start the engine and open the vent on top of the engine until you see coolant leaking out.
6. Use the engine while watching the temperature and level in the reservior.
I hope my comments help you.
