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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: Blue on November 20, 2016, 08:23:41 AM

Title: Fan is coming on early.
Post by: Blue on November 20, 2016, 08:23:41 AM

My fan used to come on about 3/4 on the gage and shut off about 1/2.  It now comes on about 5/8 and shuts off at about 1/8.  Meaning it is running almost all of the time. 

I think my temperature sensor is bad.  What do you think?

Title: Re: Fan is coming on early.
Post by: kris on November 20, 2016, 08:36:22 AM

Get the ohm meter out and give it a whirl!

Title: Re: Fan is coming on early.
Post by: Laitch on November 20, 2016, 08:46:41 AM

Quote from: kris on November 20, 2016, 08:36:22 AM

Get the ohm meter out and give it a whirl!

+1
How old is your coolant and where's its level on the reservoir gauge? Is the radiator cap sealing tightly? Is your thermostat working properly?

Title: Re: Fan is coming on early.
Post by: Blue on November 21, 2016, 08:22:51 AM

Decided to replace the coolant yesterday.  The radiator and overflow are full and the cap is tight.  The thermostat is opening and closing.  Still have the fan cycling on sooner than in the past.  I think it is going to wear out the fan because once the needle gets past the blue the fan comes on.

Title: Re: Fan is coming on early.
Post by: Laitch on November 21, 2016, 08:30:41 AM

Quote from: Blue on November 21, 2016, 08:22:51 AM

Decided to replace the coolant yesterday.  The radiator and overflow are full and the cap is tight.  The thermostat is opening and closing.  Still have the fan cycling on sooner than in the past.  I think it is going to wear out the fan because once the needle gets past the blue the fan comes on.

If the thermostat is opening at the correct temperature then it's time to remove the temperature sensor and check its function in heated water as both you and Kris mentioned.

Title: Re: Fan is coming on early.
Post by: The Mighty Gryphon on November 21, 2016, 09:58:47 AM

I would not be as concerned about wearing out the fan as I would the engine never getting to full operating temperature because the fan is cooling things too much. 

Check that temperature sensor behind the radiator.