Oil level & curves vs. pressure

[06 Bill]

GM 4106, After driving a well warmed engine the oil pressure drops off
from 40 to as low as 15 at times on left hand turns. The amount of drop is
influenced by speed and sharpness of the curve. Pan is new with all the
proper baffles in place. Oil level does influence some also. Very little
fluctuation if right up full. Any suggestions.   TIA  06 Bill

[Utahclaimjumper]

 How have you defined "full"??>>>Dan (should be 7 gallons)

[wg4t50]

New Pan, what else is new, maybe a different oil pickup ? Why a new pan ?   Either way, you will learn that keeping the oil up to proper level is cheaper than guessing and playing with 15 psi, Think the min is 25 psi (If I remember that far back).  For me, anything under 40 psi is needing attention, also are you running #40 oil or a 15W-40 or what are you using for oil ?
The crazy part, the modern Cummins engines, ISM, run 35 psi, the older M11 ran 60 psi, but today Cummins says 35 is very fine, and saves fuel.  That is not true with the DD 2 strokes like used in the 4106 etc.
Dave M

[06 Bill]

I use 7 gal. (28 qts) in the pan + approx. 2 1/2 in the filter fill on an oil change. Reason for new pan was rust through
in a couple of spots. When removed baffles were laying in bottom of pan hence new pan. Pulled pick up tube down and checked out OK & cleaned screen however it was very clean. V730 tranny pan also rusted through, welded that one up. New England you know, and now they salt with liquid. The dry salt did not get into every spot on vehicles, liquid does a much better job lol.    06 Bill

[Cary and Don]

Are you sure you have the right dip stick?  Sometimes they have been replaced with the wrong length.

When we first got our 4107 it had lousy oil pressure.  We knew the engine was pretty new.  It turned out that there was a little bypass valve in the oil system that made sure the engine got oil even if the pump wasn't working??? I think, it's been a long time.  Anyway it was stuck open.  Fixed that and we had great oil pressure.

Don and Cary

[luvrbus]

They have 2 valves inside the oil pan on each side of the block one is a bypass valve to dump the oil the other is a pressure valve some times the valves needs to be shimmed, lot of work to shim the valves on a GM was it a problem before ? 

[OneLapper]

06Bill,

You bring up the same issue that I'm having with my 4106.  In simple observation, the oil doesn't seem to pick up the oil when taking a long sweep left hand corner.  I removed the oil pick up screen and tube, inspected all of it for cracks, etc.  The pan is in excellent condition, baffles are intact, etc.  

If you take into account the observation I made when I took my 800 mile test run with the new engine, when I checked the oil the first 6 or so times, I did so by pulling over, shutting the engine off, walking to the back of the bus, checking the oil, adding a couple qts and hitting the road again.  I did this many times and wondered where the oil was going. The next day, the oil level was over full by 4".  As the oil fails to return to the sump, the oil pressure drops.  A simple test is coasting down a slight hill or coasting to a stop.  When the engine idles for a minute and you then bring it up to operating RPM, the oil pressure raising to where it should be.  Over the next few minutes, it lowers again.

I have not figured it out yet but I think it's either one of these two issues:  1) oil level is too high and the oil is foaming, the oil pump is sucking up the foamed oil and the pressure drops.  2) The oil level is not returning to sump, thusly the oil pump is sucking air and the oil pressure drops.

I know my dip stick and dip stick tube are a mish-mash of parts, but I put 7 gallons in when I change the oil.   I've had as much as 9 gallons in it with the same issue.  I've had 5 gallons in it, again, same issue. 

Mark  

[luvrbus]

Relocate the sender to a different location and give that a try always a left handed problem with a GM guys going from 14 or 1500 + rpm to make left turn at lower rpm they drop like a rock below 1000 rpm when hot I wouldn't worry about my self they do fine with 25 lbs at 1200 rpm and 30 lbs at 2100