No oil pressure while cranking

Discussion in '94-95 5.0 - Specific' started by gnx547, Jun 6, 2015.

  1. gnx547

    gnx547 Active Member

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    I disabled the fuel & ign and I cranked the motor for a few secs to build oil pressure through the engine. While cranking the oil pressure needle did not move at all. I checked to make sure the oil sending unit is plugged in and it is. I removed the sending unit and oil did come out, so I know there is some pressure. I hooked up an oil pressure gauge and cranked the motor for a few secs there is no pressure reading on the gauge. I removed the distributor and spun the drive shaft with my drill and I have oil pressure reading on the gauge. Why is it that I don't have any pressure reading on the gauge when I'm cranking the motor? Any ideas?
     
  2. ttocs

    ttocs Legend

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    I am not all that sure that the gauges have power while cranking. There are two types of ignition wires regular ignition and true ignition. A true ignition wire will have power on it with key on AND while cranking but this is mainly for the ECU/fuel pump/necessary items. I would not be surprised that the gauges are on a regular ignition(that does not have power while cranking).
     
  3. RichV

    RichV Well-Known Member

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    Because you need some RPM on the pump driveshaft. A drill will be anywhere from 1000 to 2000+ rpm. If you watch a distributor move while you crank the starter it moves much slower.

    I wouldn't be concerned. If you had pressure with the drill you should be fine. Although I forgot a galley plug on my build once, but I didn't know until I started the car.
     
  4. whiplash473

    whiplash473 Moderator Staff SN95 Supporter

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    I haven't ever payed attention to this in my Mustang but I do know in my Silverado there's no oil psi while cranking. About a couple seconds after it fires up the gauge needle moves to it's reading.
     
  5. evilcw311

    evilcw311 Most Evil Mod! Staff Member Staff

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    Don't forget that in the 94-95 cars the oil "gauge" is not really a gauge. It only shows in the normal when it sees a certain amount of pressure. Our cars have an oil pressure "switch", not a true sending unit.


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