Oil pressure high after oil change
09-09-2009, 06:39 AM
#5
09-10-2009, 11:56 AM
#10
you guys crack me up,
you really don't how how pressure works.
the oil pump is the only thing that pressurizes the oil.
the oil gets pulled from the oil pan into the oil pump, where it leaves pressurized, and then passes through the oil filter, then up to lifter galley where the oil pressure sender is located. The oil pressure sender is AFTER the oil filter in the circuit, there is no way that the oil filter can cause higher pressure! If the filter was clogged then oil would not flow through it, and if you were to conclude you would see less oil pressure then you would be partially correct because there is an oil filter bypass valve for that reason- if the oil filter blocks oil flow and pressure builds up the bypass valve allows oil to "bypass" the filter so you shouldn't see lower pressure.
And the level of oil in the oil pan has nothing to do with oil pressure, except if there's not enough oil in the pan and the oil pump sucks air then you would have no pressure.
the only things that can cause high pressure are a stuck relief valve on the oil pump, or an oil of higher viscosity or the oil is cold making it's viscosity higher.
Or you have a malfunctioning oil pressure sender or guage.
09-11-2009, 09:15 AM
#12
I put in 5 Qts and the dipstick shows right in the middle of the "full" hash marks.
you guys crack me up,
you really don't how how pressure works.
the oil pump is the only thing that pressurizes the oil.
the oil gets pulled from the oil pan into the oil pump, where it leaves pressurized, and then passes through the oil filter, then up to lifter galley where the oil pressure sender is located. The oil pressure sender is AFTER the oil filter in the circuit, there is no way that the oil filter can cause higher pressure! If the filter was clogged then oil would not flow through it, and if you were to conclude you would see less oil pressure then you would be partially correct because there is an oil filter bypass valve for that reason- if the oil filter blocks oil flow and pressure builds up the bypass valve allows oil to "bypass" the filter so you shouldn't see lower pressure.
And the level of oil in the oil pan has nothing to do with oil pressure, except if there's not enough oil in the pan and the oil pump sucks air then you would have no pressure.
the only things that can cause high pressure are a stuck relief valve on the oil pump, or an oil of higher viscosity or the oil is cold making it's viscosity higher.
Or you have a malfunctioning oil pressure sender or guage. That makes sense, but (and this is strictly a theory, as I have no knowledge of physics other than what I learned in high school 20 years ago) hear me out.
Lets say the oil pump projects the oil out at 70 psi, would the pressure not be reduced after it leaves the oil filter, and if the filter is bypassed, remain at 70 psi since there is no longer a resistance. Sorry, I'm an electronics guy and I see that diagram as a current flow diagram with the filter acting as a resistor.
Speaking of electronics, where is the sending unit on a 5.3 and is there a chart for ohms ~ psi. I'd like to meter it out and see if it's functioning correctly.
you guys crack me up,
you really don't how how pressure works.
the oil pump is the only thing that pressurizes the oil.
the oil gets pulled from the oil pan into the oil pump, where it leaves pressurized, and then passes through the oil filter, then up to lifter galley where the oil pressure sender is located. The oil pressure sender is AFTER the oil filter in the circuit, there is no way that the oil filter can cause higher pressure! If the filter was clogged then oil would not flow through it, and if you were to conclude you would see less oil pressure then you would be partially correct because there is an oil filter bypass valve for that reason- if the oil filter blocks oil flow and pressure builds up the bypass valve allows oil to "bypass" the filter so you shouldn't see lower pressure.
And the level of oil in the oil pan has nothing to do with oil pressure, except if there's not enough oil in the pan and the oil pump sucks air then you would have no pressure.
the only things that can cause high pressure are a stuck relief valve on the oil pump, or an oil of higher viscosity or the oil is cold making it's viscosity higher.
Or you have a malfunctioning oil pressure sender or guage.
Lets say the oil pump projects the oil out at 70 psi, would the pressure not be reduced after it leaves the oil filter, and if the filter is bypassed, remain at 70 psi since there is no longer a resistance. Sorry, I'm an electronics guy and I see that diagram as a current flow diagram with the filter acting as a resistor.
Speaking of electronics, where is the sending unit on a 5.3 and is there a chart for ohms ~ psi. I'd like to meter it out and see if it's functioning correctly.
Last edited by OnA Fan; 09-11-2009 at 09:32 AM.
09-11-2009, 12:04 PM
#13
if you squeeze your garden hose, the pressure goes up only on the faucet side, between where you pinch and upstream towards the faucet where the pressure is coming from. Likewise with the engine, if your oil filter is the pinch then pressure will only increase between the oil filter and the pump, and the oil pressure sending unit is not between there. When you pinch your garden hose, the pressure does not go up at the open end of the hose.
In fluid dynamics, Bernoulli's principle states that for an inviscid flow of a [ideal] fluid, an increase in the speed of the fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid's potential energy.
inviscid flow is flow of a fluid that is assumed to have no viscosity.
Motor oil is viscous, it has viscosity, your reference to bernoulli is completely out of context, or wrong.
10-04-2009, 11:41 PM
#14
I think this will provide some good clarification for those not familiar with oil pressure as it did for me:
http://lubricants.s5.com/oil_pressure.htm
As you see from this webpage, abnormally high oil pressure is cause for alarm, so I suggest that you tell the person who owns this vehicle to lay off it until an investigation is carried out.
http://lubricants.s5.com/oil_pressure.htm
As you see from this webpage, abnormally high oil pressure is cause for alarm, so I suggest that you tell the person who owns this vehicle to lay off it until an investigation is carried out.
10-05-2009, 07:32 PM
#15
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I think this will provide some good clarification for those not familiar with oil pressure as it did for me:
http://lubricants.s5.com/oil_pressure.htm
As you see from this webpage, abnormally high oil pressure is cause for alarm, so I suggest that you tell the person who owns this vehicle to lay off it until an investigation is carried out.
http://lubricants.s5.com/oil_pressure.htm
As you see from this webpage, abnormally high oil pressure is cause for alarm, so I suggest that you tell the person who owns this vehicle to lay off it until an investigation is carried out.
If it wasn't getting proper lubrication, right from the start, it would seize up. The boundary layer lubrication properties of your oil do more to prevent cold start scuffing and wear than any other single factor. Don't expect really great boundary layer properties from ANY off the shelf oil. This would include Mobil 1 regardless of the country of origin, Royal Purple, and a host of others.
Last edited by fleetmgr; 10-05-2009 at 07:40 PM.
10-07-2009, 09:26 PM
#16
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it wont hurt to spend the couple bucks for a new filter. my buddys alcohol car had only 30 psi of oil pressure after the oil was changed. we changed the filter and it went back up to spec. shitty filter. rare but it does happen
10-08-2009, 02:41 AM
#17
If it wasn't getting proper lubrication, right from the start, it would seize up. The boundary layer lubrication properties of your oil do more to prevent cold start scuffing and wear than any other single factor. Don't expect really great boundary layer properties from ANY off the shelf oil. This would include Mobil 1 regardless of the country of origin, Royal Purple, and a host of others.
Does German Castrol 0W-30 offer any better boundary layer protection? I know many rely on this for its quick flow response when cold along with good protection at hot temperatures.
My oil pressure has stayed consistent throughout the last 2 oil changes (don't know prior because vehicle was not in possession). On a cold start, I'd get approximately 40 psi idle, and then steadily moves down in accordance with the operating temperature, with the lowest I've seen it go is approximately 21 psi idle. The 21 psi is when the engine idles for a long time without moving, such as traffic jams or for the sake of observation. Then in normal traffic, it will go back up to around 30 psi @ idle if I move consistently for a while, such as on the freeway. So it seems that the coolant temperature can lower the oil temperature. At 2k RPM, pressure will be around 42 psi in neutral, but around 48 under load, so that's evidently a factor as well. However, the oil pressure can be as high as on a cold start when the coolant temperature is up, I'm guessing that the oil cools faster.
Here are pictures showing the above trend. Note that the first picture isn't a cold start, but the pressure is as on a cold start:
10-08-2009, 09:34 AM
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I agree, that looks low on cold start. My 96 likewise shows 55-60 cold, and that's with 90k on the clock. Looks like your bearing clearances may be opening up some.
For better boundary layer protection, look to companies like Hydrotex, Lubrication Engineers, Shaefer etc. Expect to pay a significant premium for these oils. What I'm using now is in $30/gallon range. The tradeoff - in my '05 PowerStroke I run about 40-45k miles on an oil change. The '96 T/A gets an annual oil change on my birthday, which makes it easy to remember. The German Castrol is still an 'off the shelf' oil, even if it's bottled elsewhere.
For better boundary layer protection, look to companies like Hydrotex, Lubrication Engineers, Shaefer etc. Expect to pay a significant premium for these oils. What I'm using now is in $30/gallon range. The tradeoff - in my '05 PowerStroke I run about 40-45k miles on an oil change. The '96 T/A gets an annual oil change on my birthday, which makes it easy to remember. The German Castrol is still an 'off the shelf' oil, even if it's bottled elsewhere.
10-08-2009, 12:10 PM
#20
I put in 5 Qts and the dipstick shows right in the middle of the "full" hash marks.
That makes sense, but (and this is strictly a theory, as I have no knowledge of physics other than what I learned in high school 20 years ago) hear me out.
Lets say the oil pump projects the oil out at 70 psi, would the pressure not be reduced after it leaves the oil filter, and if the filter is bypassed, remain at 70 psi since there is no longer a resistance. Sorry, I'm an electronics guy and I see that diagram as a current flow diagram with the filter acting as a resistor.
Speaking of electronics, where is the sending unit on a 5.3 and is there a chart for ohms ~ psi. I'd like to meter it out and see if it's functioning correctly.
That makes sense, but (and this is strictly a theory, as I have no knowledge of physics other than what I learned in high school 20 years ago) hear me out.
Lets say the oil pump projects the oil out at 70 psi, would the pressure not be reduced after it leaves the oil filter, and if the filter is bypassed, remain at 70 psi since there is no longer a resistance. Sorry, I'm an electronics guy and I see that diagram as a current flow diagram with the filter acting as a resistor.
Speaking of electronics, where is the sending unit on a 5.3 and is there a chart for ohms ~ psi. I'd like to meter it out and see if it's functioning correctly.