Overheat alarm not testing right on johnson gt150

[snake91876]

i have a 1989 johnson gt150 that i just bought, removed vro and premixing , just got back running on muffs in yard and heads are real hot cant even touch them hardly. I was wondering if this is normal i test the tan overheat wire going to the thermostat in head and i ground it coming from harness and get no alarm with key switch on. what can i do to fix and tell if engine is right temp, its not peeing real hard but steady cold stream. what should i check next, thermostats, water jackets, any suggestions i pulled lower and pump is brand new but some water is in area around pump housing should this be like this.
thanks matthew

 

[emdsapmgr]

Re: Overheat alarm not testing right on johnson gt150

The grounding of one/both tan head switches should turn on the warning horn. You could test wiring to the horn to see if the signal is reaching it or not. Unlikely that both head switches would both be bad. You can have a good impeller and the engine can still overheat if the cooling water can't get out of the block. I'd rent a laser temp gun from a local NAPA store and check the cyl head temps. They should be 143-150 when running at idle. The hot horn will sound at 212 and stay on till powerhead temps get back down to 175. If the heads are actually overheating, pull both thermostat covers off and (check or replace) the stats. When you are in the thermostat housings, check the pressure relief valves to make sure these nylon valves are not heat-deformed, preventing them from functioning.