This problem started at the beginning of the season first time out. When underway between 1000 and 1200 RPMs the engine temperature was going from 170s all the way up to 200 a couple times and the overheat alarm went off one time and went in to slow mode. Again this was just while going 1200 rpms and I was just starting to open it uip to get on plane.. If i back it down it to 800 rpms temps go back to 160s if i bring it up to 1500 rpms it cools down to the 150s to 140s. It doesn't do this in neutral.
Water temp when running boat was low 140s and the water pump was replaced as part of 3 year PM and to resolve this issue. Now it's in the 130s when i'm running 4000 to 5000 rpms and at first it semmed to resolve my issue but now problem is back. Thermostats were replaced. It's still 130s when running and 160s at idle and 800 rpms under way but now when I cruise at at 1000 to 1100 rpms it's hitting low 200s but the alarm isn't going off. I used an infrared heat gun and at first temps wre around 140s to 150s on both sides of the motor and on the cooling hoses so I thought this was just a bogus reading or something but then all of a sudden the temp was 50 - 60 degrres hotter on the port side when aiming the heat gun at the head and crankcase. Still alarm never went off. Idled it back to dock and tested and both sides were in the 140 to 150 range.
Doesn't make sense to me, if there was something to cause the port side to over heat like a blockage or something I think I should see that at other RPMS too.
Bringing it back to dealer this week but any info would be appreciated.
Your dealer should check the engine's water pressure readings at various rpms with the published specs from the factory and to check for aerated water at that problem rpm. In some cases the high flow water inlet screens help.
The Evinrude E-TEC 150 HP has a different cooling system and engine design than your motor.
The overheating alarm comes on at 194°F for the engine above 2000 rpm and 212°F below 2000 rpm.
The EMM can also give an overheat alarm and slow the motor down to 1200 rpm, the same an an engine block overheating condition. Make sure there is no debris restricting the water flow through the EMM or the vapor separator tank. The EMM stores codes internally telling when the overheating occured, how many times, which component or cylinder head, and how hot it got. Ask your dealer for a printout of the engine report for your reference.
The EMM engine sensor fits into a cavity in the cylinder head and uses a thermal joint compount to transfer the heat from the engine to the sensor tip. That way the sensor detects quickly any thermal changes instead of waiting for air around a sensor to react as with other types of engines.
A pyrometer on the top of a cylinder head would record a slightly different temperature than the temp sensor deep inside the head.
Not unless you forgot to re-install the overboard indicator plug and nozzle.
Thanks for all your input. Spoke to dealer he said since replacing the water pump seemed to temporarily fix the issue he's going to try replacing it again. He has had this with other E Tecs in the past. Dropping off the boat Saturday and he said the Evinrude rep was supposed to be there next week and he'll see what he thinks.