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Fresh Rebuild N14 Oil pressure

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Wrench_Shaker, May 11, 2017.

  1. May 11, 2017 #1
    Wrench_Shaker

    Wrench_Shaker Bobtail Member

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    Rebuilt a N14 Celect Plus cummins. My Oil pressure bounce up to 65 when fired up immediately(2 second or so) then settle right on 35 on manual gauge and 40 on the electric OEM gauge.

    After warming up it only holding 35 at 1600rpm. It floats or bounces on the electric gauge 5psi 30-35. I installed a after market sending unit and gauge it bounces all over....jumps to 65psi and then bounch 10 to 35psi back and forth. While the manual stay steady.

    I'm wanting more oil pressure than 35 psi think it should be closer to 40 45 psi at higher rpms....I installed new cam bearing, new cooling nozzle, rods bearings, new connecting rods, liner,pistons, New oil pump, New oiler cooler, new oil thermostat, new cooling thermostat. New turbo lines. Turbo shaft seems tight and in specs.

    I did not replace the signal line is the only line i didn't replace. Like it said i think pump has more power because it bounces high at first start up then come back quickly in a split second. Oil regulator came internal on the pump. Any thoughts?
     
    Wrench_Shaker, May 11, 2017
    Wrench_Shaker, May 11, 2017
    #1
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  3. May 11, 2017 #2
    boneebone

    boneebone Road Train Member

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    Cummins Engines are not engineered to run with high oil pressure.

    Normal oil pressure at idle is usually about 10 psi and at 1400-1500rpm it should be around 30psi.

    Cummins are low oil pressure, high volume engines, that's the way they were designed.

    The psi numbers you're seeking are more in tune for a Detroit engine, you're not going to get those numbers with a Cummins.

    The psi numbers you're posting for your rebuild are normal.
     
    Last edited: May 11, 2017
    boneebone, May 11, 2017
    boneebone, May 11, 2017
    #2
    Wrench_Shaker Thanks this.
  4. May 11, 2017 #3
    Wrench_Shaker

    Wrench_Shaker Bobtail Member

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    Well that's good news. I thought it looked like the Oil regulator was just cutting back pressure and i was reading the manual and it says it starts dumping oil when it reaches 35psi. I used a geniue cummins oil pump. I take it all is good then on the lube side.

    I'm waiting on a Vibratech harmonic balancer for it since it's original to the engine. I'm really curious how much damping effect its lost.
     
    Wrench_Shaker, May 11, 2017
    Wrench_Shaker, May 11, 2017
    #3
  5. May 12, 2017 #4
    Smellfunny

    Smellfunny Road Train Member

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    The Cummins N-14 is set to maintain around 35 PSI. Anything higher than that will activate the regulator in the oil pump and send it back into the oil pan.

    Cummins Manual ---
    The pressure regulator remains in the closed position until the pressure in the main rifle reaches approximately 241 kPa [35 psi].
    At that point, the oil pressure from the main rifle oil pressure regulator, acting against the end of the regulator plunger, overcomes the force of the regulator plunger spring.
    The pressure regulator plunger moves downward (open), uncovering the dump port in the regulator cavity. This allows any oil in excess of the amount required to maintain 241 kPa [35 psi] to return to the oil pan.
     
    Smellfunny, May 12, 2017
    Smellfunny, May 12, 2017
    #4
    Wrench_Shaker Thanks this.
  7. May 12, 2017 #5
    Smellfunny

    Smellfunny Road Train Member

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    I answered the question and then came back and saw you answered it yourself. HAHA after I did all that work of looking it up and typing it out I will just leave it there.
     
    Smellfunny, May 12, 2017
    Smellfunny, May 12, 2017
    #5
    Wrench_Shaker Thanks this.
  8. Jul 5, 2017 #6
    Webpirate

    Webpirate Bobtail Member

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    I have an unrelated question if that's OK, I just figured since you rebuilt the engine you or someone in the thread would know the answer. The n14 we picked up has 2 different coolant thermostats and we can't find information on which thermostat goes into which spot since the holes look the same. Does anyone have any information that can help? The engine is ntc400 .
     
    Webpirate, Jul 5, 2017
    Webpirate, Jul 5, 2017
    #6
  9. Jul 5, 2017 #7
    Heavyd

    Heavyd Road Train Member

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    I checked my Cummins QuickServe. N14 Celect is far back as it goes and doesn't show any service manuals for those. Are both thermostats the same temp?
     
    Heavyd, Jul 5, 2017
    Heavyd, Jul 5, 2017
    #7
  10. Jul 6, 2017 #8
    Webpirate

    Webpirate Bobtail Member

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    Thanks for the fast response. We actually figure it out but we had to do it in a round about way since none of the shop manuals gave us much information.
    We figured out that 1 of the thermostats is called a bypass thermostat and the other is called a radiator thermostat. Then we went on eBay to get pictures of which thermostat was which one.
    That's how we were able to determine which one went where...
    Apparently one closes at 187degrees and the other opens at 173 degrees.. That's the way I understand it..
     
    Webpirate, Jul 6, 2017
    Webpirate, Jul 6, 2017
    #8
  11. Jul 6, 2017 #9
    Heavyd

    Heavyd Road Train Member

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    Ok, sound about right.
     
    Heavyd, Jul 6, 2017
    Heavyd, Jul 6, 2017
    #9
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