"I have had this motor since 2
"I have had this motor since 2001. It had ~580 hours on it then (if the timer is correct). The engine ran well and continues to run well with exception of the overheat alarm coming in. Originally in 2003 when it came in the first time I suspected low water flow. The console mounted pressure gage was running about 20 psi at 4000 rpm. I changed the impeller with upgrade kit and the pump pressure was running 30 psi at 4000 rpm. This was near the end of the season and the few more times I used the boat it did not come in. In 2004 it came in sporadically when running at 3800 rpm and higher (it never comes in at idle or motoring along at a slow planing speed or when flushing it etc). I used a pyrometer to check the head and thermostat housings in 2004 to try to find the problem. The temps I was seeing were as high as 163 degrees. The stbd side was always slightly warmer (5 degrees) than the port side which the Evinrude rep said was normal. He suspected a bad sensor. This was so sporadic that some days it would never come in while running no matter what rpm.
Calls to Evinrude were helpful: Evinrude suggested unplugging the sensor wire to determine which side was causing the problem, then careful inspection of the t/stats and boiling them the verify they are functioning properly.
Result: The stbd sensor is the one that alarms (always). The port side has never alarmed. The t/stats start opening at 145 degrees and work fine. I have had them apart and there was no silt or trash blocking them. In 2005 I had the engine in for service since it needed a shaft seal. I had them check the engine out and they were sure it was not overheating. I had the stbd sensor replaced. Carbs were rebuilt and the motor seemed happy for the rest of the season. Summertime water temps run in 70s and 80s. No problems were seen in 2006 but we did not use the boat a lot that season. In 2007 we did not have any problems either until the fall. In December (water temps in mid 40s) It came as before when running at 3800 rpm and greater. Water pressure was still good by the gage (~25psi). I was suspecting some pump impeller wear with the reduction in pressure.
I took the boat back to the shop and they checked it out and could not get it to overheat (they are running it under the same conditions though so I understand why they cannot find the problem). I had them replace the sensor again since seemed to be where the information was leading. ON 01/11/2008 I had the boat out again to see if it was fixed. It isn't, the alarm is coming in again as before. It should be noted that this motor never overheats while on the earmuffs or idling along like when trolling etc and when it does it is sporadic.
I have removed the stats and boiled them again. They operate at ~145 degrees still (one is slightly sooner than the other). The stbd sensor was tested and it alarms at 201 degrees (the manual says 197 to 209 degrees). None of the plugs are being steam cleaned from a head gasket leak. Each looks the same. I did a compression check. cylinders 1=110, 2=125, 3=123, 4=125 (this was done with throttle wide open, all plugs removed and engine warmed until the S.L.O.W feature cuts off. I added a table spoon of 2 stroke oil cylinder 1 and rechecked it. It went to 122.
The shop think I may have a head gasket leak that is letting compression gasses into the water jacket. They are a little concerned about the low compression but say it is on right on the borderline of needing something done.
Could the rings in that cylinder be stuck causing this problem? I have never decarbonized this engine.
Could something be stuck in the cooling passages causing overheat condition at higher rpms? One thing I have learned (or think I have) is that the way these t/stat operate is that with increased pressure they actually open (or better said the diaphragm allows it to unseat) to allow water into the head. Is this correct?
I am able to remove the heads etc and do repairs like this but I really would like to have some idea of what problems may be and what direction I should take. before I start throwing money at this.
Any help is appreciated."
"I have had this motor since 2001. It had ~580 hours on it then (if the timer is correct). The engine ran well and continues to run well with exception of the overheat alarm coming in. Originally in 2003 when it came in the first time I suspected low water flow. The console mounted pressure gage was running about 20 psi at 4000 rpm. I changed the impeller with upgrade kit and the pump pressure was running 30 psi at 4000 rpm. This was near the end of the season and the few more times I used the boat it did not come in. In 2004 it came in sporadically when running at 3800 rpm and higher (it never comes in at idle or motoring along at a slow planing speed or when flushing it etc). I used a pyrometer to check the head and thermostat housings in 2004 to try to find the problem. The temps I was seeing were as high as 163 degrees. The stbd side was always slightly warmer (5 degrees) than the port side which the Evinrude rep said was normal. He suspected a bad sensor. This was so sporadic that some days it would never come in while running no matter what rpm.
Calls to Evinrude were helpful: Evinrude suggested unplugging the sensor wire to determine which side was causing the problem, then careful inspection of the t/stats and boiling them the verify they are functioning properly.
Result: The stbd sensor is the one that alarms (always). The port side has never alarmed. The t/stats start opening at 145 degrees and work fine. I have had them apart and there was no silt or trash blocking them. In 2005 I had the engine in for service since it needed a shaft seal. I had them check the engine out and they were sure it was not overheating. I had the stbd sensor replaced. Carbs were rebuilt and the motor seemed happy for the rest of the season. Summertime water temps run in 70s and 80s. No problems were seen in 2006 but we did not use the boat a lot that season. In 2007 we did not have any problems either until the fall. In December (water temps in mid 40s) It came as before when running at 3800 rpm and greater. Water pressure was still good by the gage (~25psi). I was suspecting some pump impeller wear with the reduction in pressure.
I took the boat back to the shop and they checked it out and could not get it to overheat (they are running it under the same conditions though so I understand why they cannot find the problem). I had them replace the sensor again since seemed to be where the information was leading. ON 01/11/2008 I had the boat out again to see if it was fixed. It isn't, the alarm is coming in again as before. It should be noted that this motor never overheats while on the earmuffs or idling along like when trolling etc and when it does it is sporadic.
I have removed the stats and boiled them again. They operate at ~145 degrees still (one is slightly sooner than the other). The stbd sensor was tested and it alarms at 201 degrees (the manual says 197 to 209 degrees). None of the plugs are being steam cleaned from a head gasket leak. Each looks the same. I did a compression check. cylinders 1=110, 2=125, 3=123, 4=125 (this was done with throttle wide open, all plugs removed and engine warmed until the S.L.O.W feature cuts off. I added a table spoon of 2 stroke oil cylinder 1 and rechecked it. It went to 122.
The shop think I may have a head gasket leak that is letting compression gasses into the water jacket. They are a little concerned about the low compression but say it is on right on the borderline of needing something done.
Could the rings in that cylinder be stuck causing this problem? I have never decarbonized this engine.
Could something be stuck in the cooling passages causing overheat condition at higher rpms? One thing I have learned (or think I have) is that the way these t/stat operate is that with increased pressure they actually open (or better said the diaphragm allows it to unseat) to allow water into the head. Is this correct?
I am able to remove the heads etc and do repairs like this but I really would like to have some idea of what problems may be and what direction I should take. before I start throwing money at this.
Any help is appreciated."
