1992 Merc 150, running warm

[gk9157]

I have twin 1992 Merc 150's with 440 hrs. Port temp is 135 idle and 150 at all other rpm ranges. Star temp runs 165 idle and 170 max at all other rpm ranges. Star exhaust is considerably warming to the touch over the port engine. Replaced both impellers and housings. Engines are new to me, no history other then salt water use there entire life. Temp readings are from the gauges, no other source. Both engines run up fine and props are stainless mirage in very good condition. Any sug. would be greatly appreciated.

 

[Silvertip]

Re: 1992 Merc 150, running warm

Sticky or lazy thermostat? Stats in both engines could probably stand replacement if you have no records of that being done -- especially if these are salt water motors.

 

[ncfish1]

Re: 1992 Merc 150, running warm

I would agree with Silvertip to do a t'stat replacement on both outboards. This will balance the low speed temp.

You may want to verify the gauges by switching the temp leads and see if the temperatures are consistant on either engine.

Running in saltwater, I would recommend using a pressure gauge to test the pump pressure(s). This will tell you if other components are in need of replacement or cleaning (poppet or water chambers).

 

[gk9157]

Re: 1992 Merc 150, running warm

I would agree with Silvertip to do a t'stat replacement on both outboards. This will balance the low speed temp.

You may want to verify the gauges by switching the temp leads and see if the temperatures are consistant on either engine.

Running in saltwater, I would recommend using a pressure gauge to test the pump pressure(s). This will tell you if other components are in need of replacement or cleaning (poppet or water chambers).

 

[gk9157]

Re: 1992 Merc 150, running warm

Silvertip & ncfish1. Thank you for your input. I will do all of the above. I will switch the leads to the temps just for the knowledge before replacing & servicing as suggested.