98 Yamaha 225efi salt water series II-false alarm? - The Hull Truth

wrat · 05-26-2009, 10:14 AM

I am hoping someone can help me with an intermitent overheating alarm that is an annoyance..

Last year, the overheating alarm would go off at random times. I brought it to the dealer who could not find an issue with it. They could not get the alarm to go off in a couple of trials. The water pump, impeller, etc were all replaced two years ago. The most common scenerio is the alarm goes off after I have run out to a fishing ground, etc and begin to troll. Or, it will go off after we have run to an area for over 20 minutes, throw the anchor, and let the engine rest. When I turn the key to the second position after the boat has rested, the alarm may go off. It has not gone off when I am running to where ever we are going. This does not happen too consistently, and I cant seem to find the root cause. Any help would be appreciated in advance.

A1 Outboard · 05-27-2009, 07:21 AM

The first thing to do is to find out if this is a false alarm. Try to borrow an infared hat gun so you can check actual engine temp when the alarm goes off. It is also possible that you have slow acting thermostat. When running at high speeds the thermostats are bypassed. When you run a slow speeds the thermostats control the engine temp for cleaner running. Engine temp at idle should be 135-140 degrees.