Logo

Mercury 150HP Running Hot? Or Not?

DPForumDog

New member
[FONT=Helvetica Neue, Helvetica, Arial, sans-serif] [/FONT]We are the 3rd owner of a rarely used 1995 Mercury 150HP 2.0 Black Max. We have owned the boat about 5 years and probably put less than 2 hours a year on the boat. The motor is original to the boat and only used in lake water. Yesterday Paw noticed that the gauge showed the engine was running hot. This may have been happening since day one and we just never noticed. The motor ran fine and we drove the 30 minutes back to our house with no problem. We never heard an alarm or buzzer. It takes 5 seconds for the tell tale hole to pee water and when it does it is very hot, but i read that is normal. Paw removed the two thermostats and ran the boat again and the gauge still showed it overheating .


1. Why would our buzzer/alarm not sound when it overheated?
2. What is normal for the temp gauge?
3. What it the best way to see if the motor is really overheating or just a gauge problem?
4. Is the Tell tale water supposed to be hot?
5. Should it take 5 or 10 seconds for tell-tale water to start peeing?
5. Any chance it is the poppit?
6.. Is there a way to check for debris (dirt dauber nest etc) in the system without tearing everything apart.?


I read that stoppages /clogs can partially blocking water flow and one website that said that clog debris was the number one cause of over heating. But another website said it was the water pump and another said the impeller.
We plan to change the impeller, pump, and two thermostats. and maybe the poppit.


This may or may not have anything to do with it, but Paw thinks the RPMS were too high, He had set the RPMS for 4000 but they went to 5000, but he attributed to excessive turbulence and current.
Any and all help appreciated,
Thanks in advance.
Granny DP
DPForumDog
 
We had previously removed the thermostats and reinstalled after the pot on the stove test comfirmed they were fine.
We replaced the pump / impeller and our telltale temp went from 160F to luke warn. The engine temp was almost 200 vs 90-100 with the new pump.
With the new pump/impeller the temp gauge never got above 15% versus 75% with the old pump.
Since changing out the pump worked we did not fool with the poppit. The rpms still go to 1200 even at idle speed but the boat runs great.
correction: Paw told me we have a 1994 model not a 1994
 
Back
Top