1999 Mercury 200HP Thermostats

[Robalo2640]

My engines started to overheat last week so yetsreday I checked the thermostats. They either rotted or the old owner removed them. I replaced them and now the water flow, out the "pee" hole has been reduced or regulated. Is this normal? I also installed new impellers.

 

[CharlieB]

Re: 1999 Mercury 200HP Thermostats

Unfortunately the 'P' stream is drawn off the discharge side of the T-stats which explains the little to no flow until the motor warms up.

Stats ARE necessary to speed warm up and help prevent 'cold seize' pistons.

A water pressure guage is highly recommended to ensure cooling.

Hopefully the new impellers cured your overheating.