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Dino Saga 060903___Oil Pressure Gauge

Discussion in 'Corbani's Corner' started by John Corbani, Sep 3, 2006.

  1. John Corbani

    John Corbani Formula 3
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    May 5, 2005
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    John Corbani
    #1 John Corbani, Sep 3, 2006
    Last edited by a moderator: Sep 7, 2017
    Dino Saga 060903___Oil Pressure Gauge

    Fixed oil pressure gauge years ago. Just saw a question about sender and gauge so thought I would make my fix the subject of this Saga. Can’t remember when this was but long before Internet and Fchat. Ten-fifteen years ago is my guess.

    Started up one morning and no oil pressure. Idiot light went off per usual so figured pressure sensor had left us. Got out the meter and a handful of resistors. Unplugged the sensor and found only one wire. Meant that power came from gauge and the sensor was a variable resistor to ground. Turned on the key and measured voltage coming down the wire. 6.5 volts, about half the battery voltage. Put a 270 ohm resistor to ground and the gauge came up to zero. Put a 100 ohm resistor to ground and read just over 85. My normal reading has always been just over the 85 mark so gauge was probably OK. Went down to 50 ohms and reading went up to about 130. 10 ohms got to full scale. Now had an idea of the resistance I should measure on the sensor.

    Switched meter to sensor lead and Ohms. Open circuit. Started engine. Open circuit. Banged the sensor and meter bounced. Something had come loose. Easy to repair if I could get another sensor. Figured it was a Fiat part and might be available from Pep Boys, etc. Pep Boys had no reference. Went to Car Quest and they had a marvelous book. Listed all of their replacement pressure sensors by car brand and included resistance range and whether resistance went up or down with pressure. Found that a Nissan pressure sensor had the right range and went the right way. Bought one and an adapter bushing to match thread. Installed it and measured about 150 psi. Added a ½ watt 47 ohm resistor in series with sensor and reading dropped to about 90. Perfect. Idle reading about 45, good. Pressure rises quickly until pressure regulator kicks in at about 2200 and then very slowly rises with revs. Back in business and a little smarter.

    Never did order a Ferrari part, not worth the effort. Don’t know if Nissan part is still available or if CarQuest still has great catalog. Worth trying in an emergency. Don’t expect the clerk to find the part for you. Ask to look through the catalogue and take your time. Used same technique finding a voltage regulator. Now that so much is on line, it probably will be harder, not easier to cross reference parts by function.

    Picture shows sensor and in-line resistor under shrink tubing. Table below shows resistor used to check 5 gauge readings. Never did calibrate the system as to accurate pressure readings but probably within the specs of a gauge that only has 3 numbers on its dial.

    Psi...Ohms
    ....0...270
    ..42.....80
    ..85.....10
    127.....50
    170.....10

    John
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  3. synchro

    synchro F1 Veteran

    Feb 14, 2005
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    Cool article, where is your index of all articles - I think it should be made into a sticky.
     
  4. John Corbani

    John Corbani Formula 3
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    Latest index was posted 9/10/06. Talk to Rob or one of the moderators about Sticky. Search on "dino saga index" and something should come up.

    John
     
  5. dignini

    dignini Formula 3

    Aug 21, 2005
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    Luigi Marazzi
    "when the temperature is between 230 and 250 deg. F and the engine revs are approximately 8000 the normal oil pressure is 85lbs sq. in............" I guess we'll wait for the engine to warm up before seeing the redline results:)
     
  6. synchro

    synchro F1 Veteran

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    Centerline Alfa in Boulder, Colorado has so many parts that crossover, that I thought I should share this with you.
    http://www.centerlinealfa.com/products/images/pages/electrical.pdf

    $37.80 for OP682 probably beats the Nissan one.




     
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  8. jselevan

    jselevan Formula 3

    Nov 2, 2003
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    Scott - thank you for the link. It appears that several of the Alpha parts may replace the Ferrari equivalent. However, do you know whether the oil pressure sending unit is "matched" to the Veglia oil pressure gauge used in the Dino? It would seem likely that Veglia had an internal, company standard such that all of their oil pressure gauges would match with all of their pressure sending units, but it is worthy of caution. I might try it.

    The Fiamm Trumpets also look inviting.

    Thanks.

    Jim S.
     
  9. synchro

    synchro F1 Veteran

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    No idea on the pressure sending unit, but so many parts are a cross-over that I'll bet Ferrari pulled them off the shelf.

    Harbor Freight has correct Fiamm airhorn set for ~$25 - trumpets, metal compressor (not blue plastic), connectors, air tubes, etc
     
  10. DinoDriver

    DinoDriver Formula Junior

    Mar 14, 2005
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    Bill Ebert
  11. John Corbani

    John Corbani Formula 3
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    Pressure/ohms table has errors. Should be:
    Psi...Ohms
    ....0...270
    ..42...180
    ..85...100
    127.....50
    170.....10

    Sorry,
    John
     
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  13. DinoDriver

    DinoDriver Formula Junior

    Mar 14, 2005
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    Bill Ebert
    Happy New Year to all! Best wishes for a great 2009!

    Jim, you mention above that you might try an Alfa substitute part for the Dino oil pressure sending unit. Did you ever do that? I'm about to begin my Dino winter upgrade projects and that's one of them. I am sooo tired of looking at low oil pressure readings that I know are incorrect. I could do what John did in this saga, but I want a more direct solution.

    Does anybody have any new ideas or discoveries since 2006?

    Bill
     
  14. synchro

    synchro F1 Veteran

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    I think this listing of sensors and locations is important enough to add to the Corbani section, the questions about them keep coming up and others may find this useful.

    Oil Pressure sensor is on top of block in the center (TAV 13, #60)
    Oil Temp sensor is in front of oil pan (TAV 2, #13)
    Oil Pressure Idiot Light switch is by oil filter on oil line fitting (TAV 13, #65)
    Water Temp sensor is on front head bank between cyls 5 & 6 (TAV 14 #28)
     
  15. wrightmercy

    wrightmercy Rookie

    May 11, 2011
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    i am having fun reading the posts. i learned another idea on how to fixed my Ferrari car if it will got to be troubled. as an auto mechanic it is very helpful to learn from other about new ideas on how to improve yourself from working on in fixing cars. it just that you don't need to rely from your auto repair manuals because you need somebody to help you. like what they say, two is better than one. thanks this forum is a very helpful for gaining and acquiring new ideas.
     
  16. BigTex

    BigTex Seven Time F1 World Champ
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    Dec 6, 2002
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    Bubba
    Welcome!

    John was a great guy.....
     

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