Mercury Over Heat Alarm

[bassin212]

I have a 1995 Mercury 60HP Outboard. The overheat alarm keeps coming on an off. Last year I had a bad R&R and it would put the overheat alarm about 2 min into idling speed on the water. This year I replaced the R&R and it would come on and off, it seemed like when I went fast it would turn off but when I'd slow down it would come on. When I idle in the yard on the muffs for a couple minutes it doesn't come on, on the occasion it does, I unplugged the cables to the Oil Resevoir to make sure I wasn't getting a low oil alarm, still went after unplugging so I'm fairly confident it's the overheat alarm.

Even when the alarm sounds I've never had issues with loss of power, bogging or anything. Always starts right up and runs fine. I removed the thermostat and it looks completely fine. Any other suggestions I should check before having it looked at? All 3 cylinders is around 110-115 PSI

thanks for any insight!

[Mac Attack]

Replace the water pump impeller.

[bassin212]

Meant to do that today, ran out of daylight

[dukhnter8]

Is it peeing good? Either plugged outlet, bad impeller or bad thermostat. Piece of weed wacker string pushed into outlet hole or change impeller and thermostat all fairly easy fixes. Google replacing impeller and thermostat.

[bassin212]

it peeing decent, but quick and easy fix anyhow. Thermostat looks fine. I plan on changing the impeller and seeing where that goes. Besides the impeller and the tubing for the tell tail, is there anything else in the lower unit I should clean up?

[dukhnter8]

The intake area may have some stuff in it but if its peeing decent probably and issue with the impeller. I changed mine on my 2001 90 hp merc and was easy replacement 5 bolts and lower unit was off then impeller cover. Biggest issue was I should have built something to hold the lower unit while I worked on it or used a vise, but still was pretty easy. You tube probably has a video on it.

[bassin212]

I changed the impeller on my older outboard to I am familiar with the process. Thanks for the heads up though.

[bassin212]

new impeller is on the way! the top Gasket didn't look great either, so just doing the whole kit. When I took off the impeller to check it last night I forgot to take note of which way the impeller was rotating. Are there any trick to figure out which way I should put the new one in?

[Mac Attack]

new impeller is on the way! the top Gasket didn't look great either, so just doing the whole kit. When I took off the impeller to check it last night I forgot to take note of which way the impeller was rotating. Are there any trick to figure out which way I should put the new one in?

rotate the prop and watch to see what way the impeller shaft turns.

[bassin212]

when you say rotate the prop, i'm assuming you mean to the right? I assumed this would determine which way to put the impeller, but wanted to be sure before installing.

[Mac Attack]

when you say rotate the prop, i'm assuming you mean to the right? I assumed this would determine which way to put the impeller, but wanted to be sure before installing.

Rotate it the way it turns to go forward when shift lever is in forward.
But yea.

[dukhnter8]

On mine, you put it in forward and when pushing the housing down you rotate the shaft clockwise while pushing down housing over impeller.

[Jethro]

On mine, you put it in forward and when pushing the housing down you rotate the shaft clockwise while pushing down housing over impeller.

Yep, that's how I do it. On all 3 of my motors.

[bassin212]

thanks everyone. I also read that it doesn't particularly matter which way the fins are placed because it will correct itself once the motor turns over and goes into gear. I'll be sure to grease everything up. Part comes in today so hopefully I get it installed tonight and am good to go for the weekend!

[Jethro]

thanks everyone. I also read that it doesn't particularly matter which way the fins are placed because it will correct itself once the motor turns over and goes into gear. I'll be sure to grease everything up. Part comes in today so hopefully I get it installed tonight and am good to go for the weekend!

Not in my case! I installed it wrong once and no, it did not correct itself at all, almost roasted my powerhead in fact!