Cat 3406b mechanical

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Djhansen04, Aug 30, 2025.

  1. Djhansen04

    Djhansen04 Bobtail Member

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    Aug 17, 2023
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    This truck im thinking of purchasing has an override switch and the guy said you have to hold it to start the truck until the oil pressure starts going up. When the truck is driving down the road its got around 60 and idle qas around 30 Has 90k on a rebuild. Im just wondering why you would have to hold that override or if thats normal for these?
     
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  3. Crude Truckin'

    Crude Truckin' Alien Spacecraft

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    Murphy switch. Protects from low or no oil pressure. Normal on older equipment. Roll on
     
  4. Deere hunter

    Deere hunter Road Train Member

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    Yeah that's a Murphy switch. A lot of John Deere people in the old days had them on their equipment. They're just an add-on an extra protection.
     
  5. Djhansen04

    Djhansen04 Bobtail Member

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    Thank you just wanted to make sure my 3406e didnt have that
     
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  6. AModelCat

    AModelCat Road Train Member

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    3406E is electronic. This is the tech they used back before computers were a thing.
     
  7. Deere hunter

    Deere hunter Road Train Member

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    If I remember right, a lot of of them came with oil, pressure and water temperature.
     
  8. Crude Truckin'

    Crude Truckin' Alien Spacecraft

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    We had one on a 1976 White Plainsman. It was even red, white and blue. I wanna say that has an Allis Chalmers engine in it.

    Most irrigation equipment runs Murphy switches too.
     
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  9. OLDSKOOLERnWV

    OLDSKOOLERnWV Captain Redbeard

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    Lot of Pop’s trucks had them. My freind owns a 1996 Case 850G long track dozer. Uses a little 6 cylinder Cummins, you have to hold the button on it as well till oil pressure jumps up on the gauge…
     
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