Engine/Transmission (1998.5 - 2002) OIL Pressure problem

[raf2000]

Initial posted this in the 911 section. Looks like less of an emergency as I investigate more. Problem started first time today, 199K miles on my 2000 auto. Oil pressure gauge dropped to 0, check gauges light came on and I heard a "ding". Happened again about 4 times on the way home when engine dropped back to idle in gear. Came home, changed the oil and filter and started truck. Oil pressure seemed OK now (about 60 cold). Drove the truck about 40 miles and observed the following. Oil pressure steadily drops below 40 and will not read above 40 again until another cold start regardless of engine speed. I stopped by the dealer, the mechanic let me install the test gauge after he burned his fingers a few times. I installed it on top of the oil filter housing at the 1/8 inch npt fitting. Dash reads about 20 psi when the Snap-On mechanical gauge says 21 at idle in gear. When I rev the engine, pressure goes to 40-70+ almost instantly on the test gauge and only gets to about 39ish on the dash gauge. When the gauge slowly drops down to about 21 indicated, it suddenly drops to 0 like I turned the key off , lights the check gauges and dings. This happens almost every time I let off the gas and the engine returns to idle speed (in gear) when the motor/oil is hot (190+). When in neutral, does not happen (engine speed and oil pressure slightly higher). I have guessed that the factory ECM program for the oil pressure gauge drops to 0 when it sees 20 or less psi? I have a virgin 2000 auto ECM. Dealer suggested a new pressure sender at $200 for the part. Going to call Cummins parts counter tomorrow and check price. Anyone an expert on this subject or had a similar experience?



FYI, oil pump is about $192 @ Cummins (Cummins PN 393 7404 at least for my engine SN) and almost FOUR hundred at the DC parts counter. . Parts guy said he doubts an oil pump as do I.

 

[rweis]

I put in a seperate OP gauge in the cubbyhole for just this situation. Cross check the two.



Could you put a gauge on a LONG (5') hose onto the oil filter and the mechanical gauge taped to the windshield where you are so you can see what is really going on as you drive? Would tell you if it is the OEM dummy sender.



BTW my gauge shows the OEM gauge is only relatively correct.



Actual/OEM

35/40

60/50

80/55



Bob Weis

 

[LFJ]

Oil Pressure.

Mine is doing it now. Has been doing it for about 6 or seven months. I have the new oil sending unit in the door pocket. But have got it in yet. Oil pressure will go on then it will go off. I haven't heard of anyone having pump trouble. It doesn't do anything except make you nervious. I will get mine changed out one of the warm days. Frank

 

[JR2]

Have a look at this https://www.turbodieselregister.com/forums/showthread.php?t=105893&highlight=Oil+Pressure



Down toward the end of the thread there is a post from me with the correct part number for an 01, but I belive it will be the same for an 00

 

[Sageair]

I have guessed that the factory ECM program for the oil pressure gauge drops to 0 when it sees 20 or less psi?

There is a reflash that keeps the ECM from reporting 0 psi under the conditions you decribe. I would strongly advise against allowing it. What if the pressure really has dropped below 20 psi? My 2001 H. O was doing the 0 psi check gauges thing. A new sending unit took care of the problem.

 

[raf2000]

Ordered #4088390 from Cummins yesterday for $75, will try it tomorrow. Agreed - I will not allow any reflash of any kind. Today, the pressure reads 40-75 BEFORE I start the engine! Shortly after the engine runs, the gauge drops to 0 and stays there. Gotta be the sender, will try it in the morning.



Wrong sender. Now the parts guy at Cummins says that Dodge makes the sending unit for the oil pressure gauge. Cummins makes one that relays pressure info to the engine computer. $165 was the quote for another try. Has anyone ever replaced the oil pressure sending unit to the OEM gauge, where did you get the part and waht was the number??