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Honda BF 150 heating alarm above 3200rpm

Mike2661

New member
I've read all articles relating to this and I'm not much closer to resolving my particular issues as I've already tried most suggested fixes. So I hope someone is out there to help me. I'm in West Africa with no support or Honda Dealers.

I have twin BF 150's on a Grady White Gulfstream with around 1,800 hours each. Years of manufacture is 2006. Port engine has no issues. Starboard engine gives me an overheating (continuous) alarm and red light when I approach 3,500rpm the engine goes into safety mode and then shuts down. It will restart imediately only for the same thing to happen minutes later. I can troll the entire day at 2400rpm with no issues whatsoever and if I keep the rpm below 3,200rpm the overheating alarm is much less frequent. This issue started at around 1500 hours and I've been trying to manage the problem. Prior to that they ran perfectly and were flushed after every outing. Though I dont have a heat gun the temperature of the pee jets are the same for both engines.

Steps taken so far;


  1. Changed both thermostats
  2. Changed the water pump complete
  3. Changed the poppet valve
  4. Flushed the entire system with a lime based chemical for hours
  5. Bought a Dr Honda diagnostic kit. No faults are logged.

The only thing left from what I have read is the sensors, ECM and possible leaking head gasket.

Any advice would be greatly appreciated.
 
Okay, Dr H does not log an overheat as a fault. First thing you need to do is run the motor at a speed that causes the over heat and let me know what each temp sensor is reading, there are three on the 150. Two of them should read around 60 - 70 degrees C and one (eng block temp ) should be around 100. I am assuming your Dr H came with a workshop manual, identify which sensor is reading high and then swap it with one that's reading normal, that way you can rule out a faulty sensor, so after swapping them out and temp readings remain the same you can rule out a faulty sensor. They can go out of range so start and that way you will know if its a faulty sensor, if not, then we will know which part of the engine is actually over heating, make sense?
 
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