Engine/Transmission (1998.5 - 2002) oil pump

[JCyrbok]

DOes anyone know if the oil pumps on our trucks are "pressure" type, meaning that they must pump a specific PSI to work correctly or if they are "volume" type meaning that they pump a specific volume despite the PSI?



What I am looking at is the low oil pressure seen with the Amsoil Dual By pass systems. My thoughts are if the volume is there then the PSI is less important, but if the pump is designed to deliver a certain PSI say to the cooling nozzles for them to work/cover the correct area than that would be more of a concern.



If anyone knows it would be a big step towards calming my concerns and towards slowing/stopping my look for an alternate system.



Thanks in advance,

J-

 

[BarryG]

ttt

 

[Cliffman]

Me too

Good post Barry. I too would like to know why the presure is lower.

 

[fox]

I think the correct answer is , it is a fixed voluume varable pressure. The voluume will change with the rpm.

Are you seeing the pressure drop at idle only?

 

[Cliffman]

Nope

 

[BarryG]

JCybrok and I have been trading pms about lower oil pressure with the amsoil dual remote system. Oil pressure is generally lower across the board and has been brought up on this board in the past. Those threads usually had the tone of amsoil bites get rid of it with no answers. At idle pressure is lower but well above specs. At speed (2000 rpm) the pressure is a tad low per the cummins specs. J's testing with a scan tool has shown that the oil pressure gauge in our trucks is truley crap in addition to a possibly crappy sending unit. It is definitely not a linear gauge. If I recall his test showed that 1/16th" below 40 on the gauge registered 38psi but 1/16th" over the 40 psi on the gauge registers 51psi. We are assuming that the scan tool uses the same sensor as the gauge. We were thinking that if volume is the same and just a little lower pressure than it is probably not really an issue. Does anyone have an aftermarket oil pressure gauge with a different sender than the stock one to compare the two against. Since Dodges tsb for the bad oil sending unit is not to replace the sender but to reflash the software to turn the gauge into nothing more than an idiot light leads me to believe that they are not as concerened with pressure as they are volume. Several have told me that just running synthetic oil will reduce oil pressure and I can say that I have personally witnessed that on previous vehicles. Aside from the obvious answer of remove the bypass unit or that you say I told you so that amsoil sucks does anyone have any comments or insite into this.

 

[Cliffman]

I always thought that the reason for the lower pressure was due to a higher quality filter. Less restrictive and cleans the oil better.

 

[jwilliams3]

From what I can tell on the Cummins engine. The oil pressure is regulated by a spring and plunger inside the filter mount.

There is also an emergency bypass spring and plunger incase of your oil filter getting clogged.



The oil pump on the engine is gear driven and is directly linked to the crankshaft gear.

The more engine rpm the more oil volume delivered to the regulatory system.



--Justin

 

[JCyrbok]

PSI vs Volume?

Then keeping all the above about the pumps, would this hold true?



If 2000rpm on a stock truck equates to said 50psi which inturn equals a specific volume of oil. Then on my truck at 2000rpm which equals roughly 40psi (warmed up) is the volume of oil pumped the same as the first truck?



My concern is that with the restriction of the by pass filter ( which is only 10% of the flow at any given time as I recall) are the cooling nozzles and all the other oil galleys etc getting the amount of oil that they need to keep my truck healthy and running very very long? Does my 40 psi cause the cooling nozzles for the cylinders to spray less oil on a smaller area than the 45 or 50psi that others see with a stock oil system?



Also I know that pressure is regulated by a spring in the stock filter mounting housing. I think it is called the Main Rifle or something along that lines. If the pressure is regulated there is there a way to bump up the pressure by a turn of a screw or different spring or something?



And finally the question of the knowledgeable TDR membership. Am I doing more harm than good with the lower PSI given my the by pass filter set up? Please qualify your answers too.



Thanks

J-

 

[Whitmore]

Pressure vs. volumn



The more resistence there is the higher the pressure will be , so a new or tight motor will have a higher pressure reading and the older or looser the motor the less pressure you will have. The same goes for volumn, a tight motor with lots of resistance will have less flow and a loose motor will have more flow. There cannot be a set pressure or volumn because these numbers will change. I am sure that somewhere out there is a baseline established from Cummins that a certain pressure or volumn is desired and I know thats what you are looking for.



take your garden hose and just turn it on and let it flow free, your pressure(flow pressure) will be say 50#



Now with that very hose if you were to close a valve on the end you will see static pressure , in other words there is no flow and the pressure is dead heading and it could be 60 or 70 #



Another example is when you fire up at cold temps, the oil is thick and willnot flow as easy so the pressure will be higher, this also means there will be less flow and the oppisite will happen with hot oil, you will have less pressure and more volumn.



Mass flow is kinda different, we are talking about heat removal, heat transfer from the friction caused by moving parts transfers thru conduction to the oil, the higher the flow rate is the better cooling you will get BUT we need to be careful not to have too much flow as we will have washout.



I am not a very good splainer but I hope this helps.



cheers, Kevin

 

[JCyrbok]

Whitmore, So there may or maynot be a problem with the lower pressures caused by the Amsoil system? My concern obviously is that there is enough oil getting to the areas of the engine that needs it.



Cummins spec for oil pressure is " minimum of 15psi at idle and 45spi at speed" I was told by a TDR member ( cant remember who) that for my truck I should consider 2000rpm as the "at speed" number. Well at 2000rpm crusing the highway at aprox 75mph I show between 39 and 41PSI on my Quick Check II setup. This is after aprox 30 miles to get warmed up. I only have 2K on the by pass and aprox 500miles on the full flow.



Idle is not a problem as I idle at aprox 26psi for the oil pressure.



What I need is help in determining if the pressure at speed is going to cause damage or if there is enough oil getting to where it needs to get when it needs to get there. I would prefer not to scrap my Amsoil system as it was not cheap for everything and is in a pretty conveinant spot for filter changes. ANyone have any ideas or are or have access to an ISB tech that might know and would actually answer. ALot of times if you go to CUmmins or DC you get the answer of " maybe it will or maybe it wont" which tends to leave a hell of alot of wiggle room in the middle for anything to happen.



Thanks in advance,

J-



PS I know that there are several others out there with the Amsoil system. What are your thoughts/concerns ref the oil pressure drop.

 

[Whitmore]

I too run the Amsoil bypass filter and understand what is going on here, basically it takes an aproximate 10% slipstream off the OEM oil filter outlet and runs thru the finish filter then is returned to the sump, this 10% slipstream would have normally been used in the motor for lubrication and cooling but instead was returnrd to the sump, so end result is you are loosing 10% of the oil volumn or flow to a constant recirculation or spillback to the sump. Personelly I am not concerned with problems and am very confident as to what the finish filter is doing for me, the oem filter filters down to 10 micron and the finish filter takes it down to 2 micron, the part I like the best about the setup is the fact that my finish filter returns thru the oil fill cap on the valve cover and I can visually watch the flow to determine the contition of the filter AND when the finish filter is spent then all the oil will still be going thru the oem filter. I plan on changing my finish filter once a year or aprox 20-25K.



Dont worry be happy. Kevin

 

[JCyrbok]

WHitmore,



It sounds like you have the single by pass? is this correct? If so are you seeing a drop in your oil pressure too with that system? I have the dual by pass system that has the full flow and the by pass mounted in series. My oil comes from the stock filter mount location to the filter head on the pass side battery mount back to the stock inlet for the filter mount. I have CPFF's billet adaptor for the stock mount location for the inlet/outlet.



I would be willing to go to the single by pass with a stock filter on the stock location but have heard that the Amsoil single by pass was made for engines with 6qt max oil capacity. Is there a bigger system for our trucks? Also were did you pick up your oil source at? On top of the stock filter mount? How often are u changing your full flow filter and are u using a Fleetgaurd? Which size by pass cartridge are u running? I have the BE-100.



Thanks for answering my NUMEROUS questions, this one worries me since I only have 23K on my truck and I'm shooting for 500K.



Thanks

J-

 

[Whitmore]

I run the single and I see no pressure difference from before, I use the BE 100 as well, I think they have a larger filter available but not sure. My pickup point comes from the top of the OEM filter housing and the return is into the fill cap. I plan on changing the filter once a year (20-25k) or if it stops flow.

I think the single is plenty good for our needs and would highly recommend it . 10micron oil vs. 2 micron oil is a no brainer for me.



JMHO, Kevin

 

[WestTN]

perssure difference

If you are using lighter weight (lower viscosity) oil then you will see less pressure since there is less resistance to flow thru the engine.

 

[JCyrbok]

OIL Weight

Nope using Amsoil 15W40 Heavy Duty Diesel. BUt could there be less resitance to flow as it is a very slick synthetic? Also going with that the pressure would not seem to be the limiting factor aslong as there is adequate volume/flow. Correct?



Whitmore, Where did you mount the filter head at? how does it mount. I have one of CPFF's battery box mounts and really like it for the dual. do you think that it might work for the single too?



J-

 

[Whitmore]

J, I have totally redone my passenger side engine compartment, the battery and airfilter are in oppisite positions and I have a homemade heatshield so my mount is on the side of the block under the turbo, I dont know if your mount would work there but it is easy to build whatever you need.



cheers,Kevin

 

[JCyrbok]

Ok thanks for all your help Whitmore, I'm sure I will be able to adapt the mount to the single if I go that route.



J-

 

[JCyrbok]

TTT



ANyone else have any opinions on the lower oil pressure with the Amsoil dual by pass systems? Are we hurting our trucks or not?



J-

 

[jwilliams3]

In my opinion,

Stick to Cummins minimum oil pressure specs for the long life of your engine.



Cummins does not just pull these numbers out of the air, they learn from extensive testing of all their products and an 80+year history.



--Justin