Help...2001 Mercury 30hp tiller 4 stroke (3 carb) warning alarm going off

[Catfishingfreak]

I got my boat out for the second time this year. Today we were heading back to the launch and the alarm by the key switch went off. It would only run about 2200 rpm after that (which it should according to the manual). I immediately looked to see if water was coming out of the p hole and it was just like always. The engine wasn't hot or anything so I put it on the trailer and brought it home. I checked the oil and it was full, I just changed the oil and filter a week ago. I then put the muffs on it and fired it up and no alarm after 20 minutes of running. I unscrewed the oil cap and looked inside while it was running and the oil was spraying everywhere inside so I know the oil pump is working just fine. I felt the temp of the water coming out of the p hole and it was barely warm..not cold, not hot. It seemed to be fine now but it still is bugging me so I pulled the thermostat and put in a pan of water and started warming it up. It started opening at 120* and by 140* it was all the way open. The engine has about 10 tanks of fuel through it since new. The only thing I did different this year is I'm running 25w40 oil instead of 10w30. Would that make a difference or is there something else I need to check out. Thanks for the help it's much appreciated.
Don

 

[thornskin]

Re: Help...2001 Mercury 30hp tiller 4 stroke (3 carb) warning alarm going off

My friend is having the same problem with overheat alarm and engine shutting down under load. His is a 2008 30hp merc tiller and he has taken it to a few different mechs and the problem continues. When the repair shops look at it they can't find any problems because it only happens under load and apparently they do not test on the water. He has changed the obvious things such as impeller and thermostat and such but same prob. Would love to know if anyone else has had this problem and how it was fixed. His engine has less than 100hrs on since he bought it new because its always in the shop and it is costing him lots of money taking it everywhere because the merc mechs don't seemed to want to deal with it. I will be replacing my 115hp soon and think I will stay away from Mercury because of this.

 

[Catfishingfreak]

Re: Help...2001 Mercury 30hp tiller 4 stroke (3 carb) warning alarm going off

My friend is having the same problem with overheat alarm and engine shutting down under load. His is a 2008 30hp merc tiller and he has taken it to a few different mechs and the problem continues. When the repair shops look at it they can't find any problems because it only happens under load and apparently they do not test on the water. He has changed the obvious things such as impeller and thermostat and such but same prob. Would love to know if anyone else has had this problem and how it was fixed. His engine has less than 100hrs on since he bought it new because its always in the shop and it is costing him lots of money taking it everywhere because the merc mechs don't seemed to want to deal with it. I will be replacing my 115hp soon and think I will stay away from Mercury because of this.

Is the alarm just for the overheating or does in include oil pressure and low oil also? Have they changed the sensor? Is it actually overheating? I would take the thermostat out and try it. If the alarm goes off I would say it's a bad sensor. Mine turned out to be too heavy of oil (25w40 vs 10w30) and the sensor wasn't reading it right and set the alarm off. Went back to 10w30 and it's been fine for months.