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Hank F.
Hank F., Technician
Category: Small Engine
Satisfied Customers: 15270
Experience:  Certified on Onan and Generac generators
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Hi i have a onan 8kw that the high temp/low oil falt protector

Resolved Question:

Hi i have a onan 8kw that the high temp/low oil falt protector switch trips after about 30 minutes of light load run time. i have replaced the impellar and checked the heat exchager and fresh water system. tbe raw water exhaust is warm but not hot. i have also checked the thermastat. Oil level checked as well. the runtime has slowly been decreasing after each reset on a lite load

any thoughs

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Submitted: 5 years ago.
Category: Small Engine
Expert:  Hank F. replied 5 years ago.
Thank you for choosing Just Answer for the solution to your problem.
My name is XXXXX XXXXX I am going to assist you with this.

There are 3 switches that will trip this breaker - the low oil pressure switch, the high coolant temperature switch, and the high exhaust temperature switch.

It is doubtful that the oil pressure switch would work for a little while and then quit, but either temp switch would do that.

To test the switches, simply unplug the wire from the switches, and isolate them so they can not touch ground. Start the set and let it run until it gets good and warm. Be sure to monitor the water temp while doing this, so it does not overheat.
Once you are sure it is up to operating temperature, simply reconnect the wires one at a time.
If the engine shuts down when you reconnect one of them, that switch is bad.

Let me know if this does not find the problem.
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