Engine oil pressure vs. RPM and load

[Begle1]

What role does load play in oil pressure?


Will an engine at 3000 RPM in gear ever produce a different oil pressure than one at 3000 RPM in neutral?

[mprmn08]

it shouldnt because the oil pump is a rpm related driven component.

[Begle1]

So there's really no reason to have anything other than an oil pressure idiot light in the engine compartment, and if it's ever in questioin, just pop the hood and rev to 3 grand and see what happens?

[burnt_servo]

So there's really no reason to have anything other than an oil pressure idiot light in the engine compartment, and if it's ever in questioin, just pop the hood and rev to 3 grand and see what happens?

you are kidding ????


oil light comes on , check your oil level ....... if adding oil doesn't fix it , stick a mechanical guage on it it and measure your real oil pressure , then carefully rev it to 3000 rpm ... assuming it isn't making bad noises ..... and see if the presure rises / stays the same / or falls off .


if switching from regular oils to sythentic .... some engines if not flushed out properly have a tendancy to plug up the oil pick up with a jelly like sustance .
i've seen this a 1/2 dozen times with various vw engines now .... i don't know if that is even possible with a cummins engine .

[SChandler]

So there's really no reason to have anything other than an oil pressure idiot light in the engine compartment, and if it's ever in questioin, just pop the hood and rev to 3 grand and see what happens?

I would rather have a gauge than an idiot light. The idiot light either only comes on when its too late or it will be set to come on so often you ignore, defeating its purpose. A gauge lets you see trends. If something is going south, gauges will let you know (if you pay attention) long before an idiot light goes off. I know when its time to add a quart of oil based on the oil pressure gauge and its readings. I would look some place else to lose a gauge in the cab.

I'm not sure what the point of your post was. Are you trying to get rid of the oil pressure gauge or ? Oh, oil pressure depends solely on oil temperature and engine speed.

[Begle1]

I'm merely justifying to myself why I don't really want to mount an oil pressure gauge in my cab.

[SChandler]

Well, like I said before, I would much rather have an oil pressure gauge than an oil pressure idiot light. Much more useful information available from a gauge. My .02.

[Ace]

Pressure is resistance to flow. It can be almost infinitely variable depending on many factors in the case of oil pressure in an engine. The oil pump itself, condition/type of oil, condition of the engine, ambient temperature and other factors all have an effect of the oil pressure generated in a running engine. It will vary more or less based on engine wear over time.

Trusting that state of affairs to an on/off switch is rather disingenuous.

[Richie O]

I know on my 93 the oil pressure goes from 20 psi at idle to about 60 psi at high idle. The factory gauge does not show much difference. I would say they are ok but hard to tell what you actually have for pressure by them.

[GLHS]

Begle, if the idiot light comes on when pressure is say 10 psi or less (I don't know where the Cummins is set), I know I would like to know if was making only 11 psi at 3000 rpm.

I am going to Cummins today just for this reason. I have an in cab video of my truck on the dyno at Edge this past fall and was surprised when I watched the video at home. Oil pressure falling pretty good above 3000 rpm.

Was told the p-pump oil pump is better than a 1st gen and a 24v is better yet.
Part number for the 24v oil pump is 4939587. Not sure what the number is for a12 valve. Supposed to have more volume and pressure. Might even grab a pressure spring too that is for a p-pump. Supposed to increase by 4-6 psi. Stock spring is set to 65psi.
I will have to let know you how it turns out.

[Begle1]

Why would oil pressure fall off at higher RPM?

[mprmn08]

a regular oil will break down with heat as apposed to a synthetic (not that synthetic doesnt just not nearly as bad and as quick) and also your oil will airate therefore the need of a windage screen at high rpms and it will blow oil away from the pump pickup or just airate it so bad the pump cant get enough to pump it. i never heard of it with a diesel cause the lower rpms they turn but we have that trouble alot with high rpm race motors. but im talking like 7000 + rpm's

[Begle1]

Cummins sells those girdles, right?

Think they were designed for windage reductions or just block strength? They'd probably keep windage down regardless, no?


I would tend to think that extra blowby in the crankcase would try to increase oil pressure, like a barometer?

[mprmn08]

well a girdle is different then a windage screen. a girdle is for strength. it basicly ties all the mains together for more strength. a windage screen is typically back by the oil pump the length of the sump area that just blocks windage from the crank from blowing oil away from the pickup and also from causeing airation. no strength adding what so ever.

[Begle1]

So the Cummins girdles aren't in a shape that would reduce windage?