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Oil pressure specifications

Discussion in 'Repairs, Maintenance, Help' started by Craig Bernhardt, Apr 4, 2015.

  1. Craig Bernhardt

    Craig Bernhardt New Member

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    My 1997 Dodge Dakota has a 5.2 L v8. Does anyone know what the oil pressure specifications are at idle and at driving speed?
     
  2. ImperialCrown

    Level III Supporter

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    The minimum oil pressure at a warm idle is 4 psi in the service manual. I would not like to see less than 10 psi at warm idle on a healthy engine. Are you having an engine noise or oil pressure warning light/gauge issue?
     
    Craig Bernhardt likes this.
  3. Rick Anderson

    Rick Anderson Well-Known Member

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    Also check the spec and +/- for the low oil pressure switch, i.e. the low oil pressure light will often light before you reach the absolute min spec oil pressure. And the O.M. will often say the low oil pressure light coming on at hot idle is permissible, as long as it goes out immediately with an increase in engine rpm. I think most Chrysler low oil pressure switches of your era would close at 10 +/- 4 PSI. If you have a low oil pressure light coming on, you need to confirm it using an oil pressure gauge to measure the actual oil pressure. The low oil pressure switches can, and often do, go bad, the wiring can short or even contamination in the connector can short it and light the light erroneously.

    Oil Pressure should increase proportionally with engine rpm till you hit the max spec (the pressure relief valve in oil pump) at redline rpm it's NOT unusual to go a bit above that pressure for the relief valve.

    Cool/Cold oil will be more viscous, so before the engine hits full operating temp, where the oil is hot, you'll see higher pressure for all conditions.

    As the engine wears, the space between the bearing increases, and oil will flow through the engine with less resistance, thus lower pressure. The oil pump wears as well, and thus makes less pressure.

    The oil pressure specs vary with the engine, like IC referred to, check the actual specs to be sure. But in general, most engines make 17PSI - 55PSI when new or like new. The lower pressure is hot idle and it should steadily climb to the max pressure with engine rpm, hitting the max pressure before redline and going a little over the max pressure at redline is NOT a problem, a good healthy engine will do that.

    As the engine wears, those pressures will drop. Like IC said, most people agree if the motor can't make more than 10PSI at hot idle, you should be very concerned. The absolute min spec in the FSM usually means the engine is totally worn out or serious oil system problem.

    If this is occurring just after an oil change, keep somethings in mind:
    *Oil viscosity is directly related to oil pressure, you should use the recommended oil viscosity in the O.M. I've seen too many people pick just a random oil viscosity that is totally wrong for their particular motor, for all sorts of ignorant reasons. Don't pick a different than recommended oil viscosity because your friend swears by it or all the new cars use it.
    *IMO, there are some very low quality oil filters on the market that should be avoided, its rare, but they can cause problems. On another forum recently there was a Jeep owner complaining of a 10PSI drop in oil pressure just after an oil change, he used one of the filters IMO should be avoided. He swapped in a more generally regarded higher quality filter and regained the 10PSI oil pressure loss.
     
  4. Craig Bernhardt

    Craig Bernhardt New Member

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    I was getting constantly low readings even at driving speed. I changed the oil pressure sensor and now it stays nice and high on the gauge. But as I was driving to Sarnia Ontario from Brantford it would sporadically drop halfway or so than go back up. I noticed that when it dropped in pressure, if I let off gas, it would go back up. I suspect oil inlet filter on pump may be plugging
     
  5. ImperialCrown

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    You could drop the oil pan to take a look. I have found silt in the pan bottom of some engines.
    You could also drive with a mechanical gauge pinned under a wiper blade to monitor pressure (if it doesn't look like rain).
     
  6. Craig Bernhardt

    Craig Bernhardt New Member

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    Yeah, I'm figuring I am going to need to drop the pan. Not looking forward to it cause the cross member goes right under it. Looks like the engine may need to be lifted to get to it. I am going to try this stuff at Walmart called Wynns Engine. Think they only sell it in Canada, but it dissolves varnish and sludge ( to a point), while you drive. Has Acetone in it
     
  7. chuzz

    chuzz Well-Known Member

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    The only thing about using something to "dissolve" sludge you need to ask, is "Where does it go?". It goes throughout your oil passages and filter. So, if you do use something like that, follow the directions and immediately do an oil and filter change. That's my .02 cents.
     
  8. 1999 White C5 Coupe

    1999 White C5 Coupe Well-Known Member

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    Before you remove oil pan - change your oil and oil filter - and use a Dodge / Chrysler oil filter. You could have a defective or partially clogged oil filter.
     
  9. ImperialCrown

    Level III Supporter

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    Follow the service manual procedures for removing the pan, if you do. The engine does have to be lifted and I believe the distributor and plastic intake have to be removed to prevent possible breakage. Other than that, it isn't a bad job as long as the engine is lifted is high enough and the crank weights are out of the way.
    Around here, oil pans have rusted out and leaked.
     
  10. Bob Lincoln

    Bob Lincoln "CHECK FAULT CODES"
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    When you changed the sending unit, did you use any teflon tape or sealant on the threads? If so, that was a mistake. The sensor ground is via the threads, and any sealant will insulate it electrically. That's a likely reason for intermittent performance.
     
  11. Craig Bernhardt

    Craig Bernhardt New Member

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    Changed sending unit a couple days ago. The original sending unit showed a flat low reading constantly, and the new sender shows occasional fluctuations. I did in fact use teflon tape, but its a 2 pin wiring plug, pin 1 is sensor ground, pin 2 is PCM signal. Wouldn't that be considered its source for ground? I'm going to go with cheapest easiest fix for now which is a good engine cleaning, with as White C5 says, a Mopar oil filter, and go from there. The frame is pretty old and rusty and before I get all gung-ho about lifting the engine I want to make sure I don't screw nothing up much further than it is.
     
  12. Bob Lincoln

    Bob Lincoln "CHECK FAULT CODES"
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    OK, then you have a wired dedicated ground, should be OK.
     

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