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I recently bought a boat with a 2 stroke 175HP Looper V6. The motor runs like a charm as a rule. The last time I had it out, I went about a mile at near full throttle 5400-5600 rpm and the overheat alarm came on and the motor went into safe mode. After idleing about a minute, the alarm stopped and the engine temp was around 180 degrees. It pees a really strong stream, it was not hot enough to make steam, and after resetting the alarm, the motor runs fine as long as I stay below 4000 rpms although after about 6-8 minutes, the gauge does indicate it is on the high side of normal.
I took it to a marine tech who did the routine checks. He pulled the thermostats and found a small piece of gasket material/silicone that was possibly obstructing the thermostat in the head with the sending unit/alarm sensor. He then checked my fuel tank for a restriction and said that although the safe mode was not activated by a fuel restriction, that too little fuel would also cause a motor to run too warm causing the overheat alarm. He found that the 3/8 inch fuel line was necked down to a 1/4 inch barb at the tank. This was corrected to a 3/8 from tank to carbs. The water pump in the motor is about a year old and he felt it was working fine. After several minutes of running on a hose, the hottest either head gets with an IR gauge is 145 degrees. I plan to take it out later today to see if we have corrected the issue. Is anyone aware of any other possibilities for the overheating other than what I have mentioned and does his explanation sound reasonable? I feel it was a combination of the fuel restriction and the particially blocked thermostat. I do know that on 2 stroke ultra-lite aircraft, a lean running engine will overheat and cause problems. I can see how the same would be true on the outboard.
Thanks
I took it to a marine tech who did the routine checks. He pulled the thermostats and found a small piece of gasket material/silicone that was possibly obstructing the thermostat in the head with the sending unit/alarm sensor. He then checked my fuel tank for a restriction and said that although the safe mode was not activated by a fuel restriction, that too little fuel would also cause a motor to run too warm causing the overheat alarm. He found that the 3/8 inch fuel line was necked down to a 1/4 inch barb at the tank. This was corrected to a 3/8 from tank to carbs. The water pump in the motor is about a year old and he felt it was working fine. After several minutes of running on a hose, the hottest either head gets with an IR gauge is 145 degrees. I plan to take it out later today to see if we have corrected the issue. Is anyone aware of any other possibilities for the overheating other than what I have mentioned and does his explanation sound reasonable? I feel it was a combination of the fuel restriction and the particially blocked thermostat. I do know that on 2 stroke ultra-lite aircraft, a lean running engine will overheat and cause problems. I can see how the same would be true on the outboard.
Thanks
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