Mariner Overheat Warning

[John Birge]

I have a 1992 Mariner 40 Magnum which I recently got from a family member. I have cleaned the carbs and replaced numerous gaskets and the initial test run went great. I disengaged the oil warning (beep that occured on startup) because I thought the sensor was bad. The initial test run went well (about 30 minutes). The second run did not go as well. About thirty miunutes into the ride the alarm went off(loud steady indicationg and oil issue). The oil res. was full. I cut the motor off and waited about thirty minutes. When I restarted the engine would idle (water was running) but when I engaged the prop it shut off. After a tow to the ramp everything started fine and I got it back on the trailer. Any ideas?

 

[Laddies]

Re: Mariner Overheat Warning

THe steady tone is for heat, not oil so you either have a bad pump or temp sender.

 

[CharlieB]

Re: Mariner Overheat Warning

Hopefully this is going to something simple, like a stuck/bad t-stat and that you shut it down soon enough to avoid any major damage.

Remove the stat and test it in a pan of water on the stove with a thermometer to see if/when it opens. If it is not open by 140 degrees, replace it.

Briefly, start the motor on the garden hose or in a barrel (preferred) while the t-stat housing is removed to check for good water flow to the t-stat. If little or no water then remove the lower unit and carefully inspect the water pump housing and impeller for any warping, cracks, and the transfer tube upper seal.

 

[Laddies]

Re: Mariner Overheat Warning

A 1992 Mariner 40 HP Magnum has no thermostat

 

[CharlieB]

Re: Mariner Overheat Warning

Oooops!

How old is his impeller? Or what's left of it.

 

[John Birge]

Re: Mariner Overheat Warning

Alright.......let me be totally forthcoming. When I received the boat the oil tank warning went off everytime I turned the key. When it was empty, and when it was full. I disengaged the sensor and ran the motor with ears and had no problem. The next logical step was to take it to the lake and give it a shot. Again, no issues. I then assumed (no jokes please) that is was a faulty sensor and it could wait until the end of the summer to be fixed. That is when the overheat came on. When I gave it about an hour to cool off it ran fine.