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What is it and where is it?

December 25, 2024, 11:24:53 am

My 95 U240 with Cat 3116 came with an Engine Air Inlet Heater.  To my knowledge it has never worked.  I have just recently became aware of it and want to make it work.  The system only has 5 parts, Heater, Control module, solenoid, water temp sensor, hobbs oil pressure sensor.
 
  What is a HOBBS oil pressure switch?
  Where is the one used in the air heater system on the engine?
  Where is engine water temp switch used in the air heater system on the engine?

According to my drawing(B-2099) there is 2 HOBBS oil pressure switches, one for the heater systems and I don't know what the other one is for.  One(1) engine oil pressure that goes to oil gauge. There are three(3) water temp things,  Eng water temp switch goes to control module, sender eng water temp goes to water temp gauge and water high temp switch go to speedo gauge.


Pat

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Re: What is it and where is it?

Reply #1 – December 25, 2024, 12:42:02 pm

Quote from: pthurman48 – December 25, 2024, 11:24:53 am

What is a HOBBS oil pressure switch?

Google AI Overview says:

"A Hobbs oil pressure switch is primarily known for its association with the Hobbs Meter company, founded by John Weston Hobbs, which originally specialized in manufacturing electrically wound clocks for vehicles, later expanding into aviation hour meters during World War II; the "Hobbs Meter" became synonymous with the company's name, and their oil pressure switches are recognized for their reliability and quality within the automotive industry.
Hobbs oil pressure switches are used to monitor engine oil pressure, triggering alerts or actions when pressure drops below a set threshold."

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Re: What is it and where is it?

Reply #2 – December 25, 2024, 09:35:08 pm

If there is an oil pressure switch in the engines air heater system, it's there to protect the air heater. If the grid does not have air flow across it, it will burn out.

Tim

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