Outboard still not fixed after shop visit....arg

[Kit Carson]

Your 4 stroke most likely has kidney stones. I love a mercury engine but their biggest problem is the water intake is big enough to allow some stone, or other foreign object to get stuck right behind the thermostat. It does not take much to restrict that small opening and so you get the high heat and shutdown mode.

On the left side of the engine you will find the thermostat housing, three bolts and the cover comes off(two on some) pull the thermostat out and I rig up a small tube on a vacuum and clean it out.

I had a small gravel stone in mine one time, it took a couple months to finally find it so I diagnosed it with a kidney stone. Lol!

As new as the motor is I doubt it is the temp sensor, could be but doubt it. Something is restricting the narrow water flow past the thermostat.

Kit

[Cane Pole]

Kidney stones eh? I read some reports on the small Merc 4 strokes. Apparently this is a somewhat common problem. I have had a couple long beeps on my Jon boat. It has a15 Merc 4 stroke 2012 motor. I read the manual about the fault. Impeller, thermostat, or loose connections. Nothing about pee stones. This is an interesting fault.

[scrat]

Thermostat sticking not opening all the way open sounds to be most likely cause. Never had one to stick on boat motor but have had this trouble with thermostats on cars and trucks before. If this was not a problem before water pump replacement it could also be they put new water pump propellers backward when replacing and is not pumping enough water.

[jaxsprat]

Will sure be interested in hearing the outcome of this I fish with some guys that have these small merc's, got to be a frustrating thing...........

[skiptomylu]

I just hate when something is wrong with my boat and I don't know exactly what it is! A real PO thing! Hope you get it figured out soon and it's an easy fix!

Skip

[chadw]

had similar issue with 2012 mer 60 4 stk....mine was mud dobbers made there way all the way up the pee tube to the backside of the thermostat and had restricted it some...I did as a previous poster said, removed thermostat and cleaned passages best i could...I useed some 150# saltwater mono or heavy weed eater line and fished it through the passages...broke it up enought that when i hooked the water to the flush out fitting, i was able to blow the rest out with the water pressure...