Mariner 150 alarm

[BP88Valero]

So i have a 1988 150 Mariner on a hydrostream valero. it starts up fine and is pumping water. After about 4-5 mins cruising at low RPM's it is going into alarm. I shut it down and give it 20-30 seconds before start up. Starts up and lets me get back to the pier.

Any suggestions on what may be the problem??

[CharlieB53]

A water pressure guage is a valuable tool in determining a cooling problem,

AND once installed lets you keep an eye on cooling pressure to prevent future problems.

A Very good investment.