1992 60 hp mercury outboard

[stevphent]

i have a 1992 60 hp mercury outboard, high temperature engine alarm went off while driving at 2000 rpm. water discharge seemed normal. parked boat, came back one hour later, turned on ignition key, alarm was still sounding. came back later in day, turned on key, no alarm, started engine, cooling water appeared, yet high temp. alarm sounded in less than 10 seconds. any ideas what could be the problem, i have been told if discharge water appears, the engine is cooling. could part of the cooling system be blocked and cooling water still appear? can the cooling system be back flushed through the cooling water discharge?

 

[CharlieB]

Re: 1992 60 hp mercury outboard

First, when was the last tiime the water pump was serviced? If more than two years then it would be a very good idea to do it as cheap insurance against another overheat.

then, Two things cause me to think you may have a faulty alarm

After sitting one hour it still alarmed, an hour should have been plenty of time for the engine to cool

After starting it alarmed within 10 seconds, it should have been well over a minute.

Before you spend a dime on NON-REFUNDABLE electrical parts, test the temp alarm sensor with an ohm meter while stone cold, retest after heating in a pan of water on the stove (on Medium) heated to 200 degrees, well steaming but not yet boiling.

You didn't mention if you felt the motor when alarm was on, the engine block should well warmed, you should be able to touch it for about 3 seconds without bunging you hand. About 165, no more than 180

 

[stevphent]

Re: 1992 60 hp mercury outboard

the engine temperature in the area of the spark plugs is as follows, bottom plug, cool, middle and top plugs warm to the touch but not hot. the sensor is in the engine block encased in a rubber boot, i am afraid if i yank on the wire that it will break off before the rubber boot comes out of the opening, then if i get the sensor out can you walk me through the procedure for testing with the ohm meter. water pump was replaced in 2001, but the cooling stream seems to have good pressure except at idle or while trolling,