Re: Onan Generator exhaust temperature switch - great price.
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WAIT and read this before you order!
Not all Onan Generators in all SMs and 54s are created equally. Use your ohmmeter to check for continuity between the terminals on the temperature sensor on the exhaust elbow. Some Onan models have part 309-0295-01 which is Normally Closed. Other models have part 309-0295 is Normally Open. Which sensor you have depends on your Onan Model and Serial. Check the parts manual for your model to determine how to test this sensor. Or call your Cummins/Onan dealer with your model and serial number.
Good to know: The normal temperature of the exhaust elbow is about 50C and the normal temperature of the coolant is about 80C. Were these in range? How many hours since the last impeller change? Should be less than 300hrs or 12 months. The impeller blades can look OK, but the impeller can be defective. You can have some water flow, but not enough to keep the elbow below about 70C (the approximate cut-off temp).
Also, remember there are a number of sensors in the shutdown system, and these switches will fail. I replaced the exhaust manifold temperature switch and the water-flow switch because of an accumulation of debris inside. I also had one situation with a loose connection on a switch. Did you use your laser temperature gun to measure temperature?
On Wed, Jul 29, 2020 at 4:02 AM Mark Pitt <mark_pitt@...> wrote: