"I just got around to reading
"I just got around to reading this thread. The powerpack has absolutely nothing to do with a overheating problem. Hopefully you kept your old powerpack as it is no doubt a fully functioning powerpack you can have for a spare. If you don't have it, I suggest that you pay your "mechanic" a visit and demand it be returned to you. Bottom line is that you paid a great amount for a component you didn't need.
Constant steady warning horn, assuming that the water supply is plentiful = Failing water pump, Jammed or otherwise failing thermostats, Debris in water tube and/or water passages, Failing head gasket that would allow the combustion to enter the water passages (check compression), Swelled and expanding water deflectors restricting water flow.
On the V6 engine, the constant steady warning horn caused by a fuel restriction, the usual restriction being......
(Fuel Anti Siphon Valve)
(J. Reeves)
Many of the later OMC V/6 engines incorporate a fuel restriction warning via a vacuum device attached to the powerhead. If the engine overheats, or if you have a fuel restriction, the warning is the same.... a steady constant beep.
NOTE... Only the V/6 & V/8 engines have the above "Fuel Restriction Warning". The warning horn will not sound on the other models.
The fact that a engine is not overheating, but the warning horn sounds off with a constant steady beep, and that the rpms drop drastically would indicate that the engine is starving for fuel due to a fuel restriction. Check the built in fuel tank where the rubber fuel line attaches to the tank fitting. That fitting is in all probability a "Anti Siphon" valve which is notorious for sticking in a semi closed position. It will be aluminum, about 2" long, and the insides of it will consist of a spring, a ball, and a ball seat. If this valve exists, remove it, knock out those inner components which will convert it to a straight through fitting, then re-install it. Hopefully that cures the problem.
The above procedure will cure a restriction problem with the anti siphon valve as stated. BUT, it may also allow fuel to drain backwards to the fuel tank when the engine is not running (siphoning backwards) due to the fact that the carburetors/fuel pump etc are higher than the fuel tank. This condition is not an absolute as the valves in the fuel primer bulb usually prevent this backwards siphoning problem. However.... if this does take place, the cure would be to install a new anti siphon valve.
Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay store at:
http://stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc?refid=store
Finally..... The horn itself has been known to fail at times and would sound constantly. The test here would be (while the horn is sounding) to remove the TAN wire form the horn. If the horn continued to sound, the horn is shorted and must be replaced."