New Cast Iron Oil Pump pressure low

[Rawze]

(12-06-2020 )smorgan87 Wrote:  RAWZE can you shed some light on why cummins engineers hate oil pressure? Is it really true more than about 50psi will not only do all of what you said but also wash out bearings? Why does a cat run 60ish forever and cummins will self destruct over 50ish? Also im assuming that my reman 2350 has an old style pump if im runnin 42 at speed?

(speculation here)...

As far as washing out bearings due to oil sneaking in behind them at higher pressures, and the engine maker reducing pressures partly due to this, I have never found any official documentation as such. It is speculation based on some cummins ppl saying this in the past a long time ago. This would depend heavily on how much retaining lip there is at the edge of the bearings to hold them in place vs allowable wear. Some engine makers have a narrow lip/catch to prevent bearing spin, some have a larger ones.

Also, Waterloo is right ... A lot of gaskets like the front gear train gasket would do well to hold up to 60 psi from all appearances without some help and it is already well known that the rear bell-housing gasket likes to leak when the engine is driven really hard/abused already. higher oil pressures would only make this worse I think.

I know that an engine with an overall lower pressure design will generally have lower oil temps and therefore need less oil cooling. A lot of this is due to less pressure at the oil pumps ball-spring regulator, which produces resistance heat in the oil.

Ball-spring regulators are notorious for causing oil temps to rise, they are a constant source of efficiency loss, and are prone to cavitation. The lower pressures that you can keep this type of oil pressure regulator, the better off it becomes. There are better designs for pressure regulators because of this very reason. A bypass-charging valve type regulator does not have these issues, but they are more complex and wear out quicker.


The lower oil pressures in an engine also benefit the engine through fuel efficiency combined with a more rounded range of operation. - I can only speculate why the red engine maker did what they did, but i would suspect these traits that I just mentioned are some of what was likely saugh after. The engine is above the minimum rating of 10 psi for every 1,000 rpm rule, so 20 psi at idle under no load is double this rating and at 40 psi, this would be tolerant to 4,000 rpm. - if anything could be guessed towards the pressure rating it is designed to run it, one can only speculate that it looks like they took the minimum oil pressure rating requirements for good diesel engine design and simply doubled them, but did not go higher ... maybe kept it to a minimum to improve efficiency? - and improve flow during cold start? reduced pressure and higher volume at the bottom of the pistons to reduce oil consumption and increase cooling effect?, lower overall oil cooling requirements>? etc..