Tight fit: New Oil Pressure Sending Unit | FerrariChat

Tight fit: New Oil Pressure Sending Unit

Discussion in 'Mondial' started by ZekeD, Oct 27, 2025 at 8:15 PM.

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  1. ZekeD

    ZekeD Karting
    Rossa Subscribed

    Dec 8, 2023
    82
    Sisters, Oregon
    Full Name:
    Zeke Duge
    My '85 QV needs a new oil pressure sender. Removing the old one was a pain. It would spin 3/4 turn and then get tight (coming off). My new (very expensive) sending unit does the same thing going on. I am fairly sure that it is not cross-threaded, and I got several turns before the 3/4 stall. I have not gotten a wrench on the hex bolt (too many pipes) and don't want to put torque on the sender. Has anyone experienced this "ok-tight-ok-tight problem? Any suggestions?

    Thanks
    Zeke (Oregon)
     
  2. theunissenguido

    theunissenguido F1 Rookie
    Owner Silver Subscribed

    Jan 21, 2004
    2,776
    Argent/Brasil
    Full Name:
    Guido
    I would try to re-thread the threads in the engine block with a thread reamer if you can find one with the same size and screw thread.
     
    Alden likes this.
  3. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    27,000
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    That's the problem -- better to remove the oil filter mount (item 19) from the engine block and replace the gasket (item 22) so that the sender can be removed/replaced on the bench (with a wrench) rather than apply any torque to the sender outer case:

    https://www.ferrariparts.co.uk/diagram/ferrari/308-quattrovalvole-usa/017-lubrication-system

    IIRC, others have done some crow's foot wrench gymnastics...
     
  4. ZekeD

    ZekeD Karting
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    Dec 8, 2023
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    Sisters, Oregon
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    Zeke Duge
    Thanks Steve. It would take a very thin C-Foot (I tried) and Giudo suggested chasing the threads, but I dont want any metal in the oil. Looks like removing the mount is the right way to go.
     
  5. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    27,000
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    Yes, I don't know how to find the thread easily, but, IIRC, it took some serious grinding, in many directions, to get the C-foot wrench to be able to work (hence the "gymnastics" ;)).
     
  6. ZekeD

    ZekeD Karting
    Rossa Subscribed

    Dec 8, 2023
    82
    Sisters, Oregon
    Full Name:
    Zeke Duge
    Snap-on makes a thin variety, but I dont have the right size (7/8 SAE would work). Even then, Im not so sure. Gaskets will be here Friday.
     

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