Oil Pressure

[puller]

]Here is a question. Why does the dash gauge go from 0 to 110? Mine runs somewhere between 40 and 100 most of the time. BUT when you put a positive gauge at the filter top it reads 30 LBS at 2500 rpms and 6 to 10 at idle. These numbers are right out of the service manual. Just wondering.



puller

 

[HBarlow]

The "gauge" is a feel good phony. It is not actually measuring oil pressure, it simulates what oil pressure should be. If op drops below a programmed level, which no Cummins B motor has done in recorded history, a cel will tell us.

 

[Shadrach]

That's why I added a real OP gauge and coolant temp one also to my pillar pod. Shad

 

[Tractorat]

Is that issue of the oil pressure guage year specific ? In other words, is there a range of years when the gauge actually showed a true oil pressure ?

 

[sag2]

Not since the Third Generation common rail trucks.

 

[AH64ID]

The 30 at 2500 and 10 at idle are MINIMUMS, and not what the engine runs.

All 03+ trucks and some 2nd gen trucks with current software do not show the real oil pressure. The 3rd gen's only have a pressure switch, so the ECM only knows if there is 6psi or not. The dash is purely an algorithm, well even that is pushing it as it show ±40 psi nearly all the time. The only time my dash gauge is accurate is at 1200-1300 rpms on a warm engine.

I run a oil psi sender on the drivers side of the block just above the ECM, it pulls pressure off the main oil rifle. On a warm engine idle is 20±2 psi, and cruise above 2000 rpms is 60-65 psi. Pressure is about 50 at 1500. As the engine warms up (towing) the pressure drops, the lowest I have ever seen is 38 at 2000 with EGT's of 1250° for 7 miles up a 6-7% grade. That was with the stock turbo, and other stock parts. Since I have upgraded several things the oil pressure has yet to go below 50-55 under the same conditions, with 50-75 more rwhp (same coolant temp too, it's amazing what the oil can see for temp that the coolant doesn't). There is a 75 psi oil pressure relief valve located in the oil filter housing, which is why from about 2000 rpms and up the pressure is constant, and with my sender being a ways from the releif valve the pressure is lower than the relief valve setting. On cold oil I can see 80-85 psi, but that's about as high as it gets.

The "gauge" is a feel good phony. It is not actually measuring oil pressure, it simulates what oil pressure should be. If op drops below a programmed level, which no Cummins B motor has done in recorded history, a cel will tell us.

On a 3rd gen nothing is programmed, it either has 6 psi or it doesn't. You could have no CEL and be at 7 psi at 3000 rpms and would never be the wiser, until your motor seized. As you stated its a very rare occurrence to have an oil pressure issue with an ISB.

 

[Tractorat]

Not since the Third Generation common rail trucks.

What about 2nd gen (2002) ?

 

[Tractorat]

Not since the Third Generation common rail trucks.

What about 2nd gen (2002) ?

 

[AH64ID]

What about 2nd gen (2002) ?

Like I mentioned some 2nd gen trucks have a working oil psi gauge, and some don't. It depends on the current ECM software.

 

[Tractorat]

Is there an easy way to determine the software ?

 

[AH64ID]

Short of hooking it up to a DRBIII I am not sure.

Does your pressure swing from ~20 at idle to ~65 at cruise? You could always hookup a gauge at the oil filter head and see if the dash matches.

 

[HBarlow]

What about 2nd gen (2002) ?

When my '01 HO/six speed was only a year or two old the oil pressure dropped to zero. A little concerned I took it to the local Dodge store and asked them to determine why. It was under warranty. A few minutes later the service writer brought the truck back saying it was fixed. Without discussion with me they reflashed the computer to send a bogus simulated signal to the dash instrument. There was no going back according to the service writer.

IIRC, I later learned on TDR that lots of oil pressure senders on '01 HO engines were failing and Dodge's cure was to simply reflash the computer to provide simulated oil pressure. I guess the engine still has oil pressure. I spoke with my mechanic friend by phone last weekend about doing a service on my truck two weekends from now. My old Ram 3500 -now his '01 Ram 3500 has 366k miles on it and still runs great.

 

[Bob4x4]

There was a parts supercedence on the 2nd gen oil pressure senders that replaced them with a switch that required an ecm reflash to make the dash read out correctly.

 

[HBarlow]

Bob,

Yeah, I remember the details now. That's what I was told when the dealer reflashed my old '01.

 

[puller]

The dealer has replaced the oil pressure sender with 3 different ones. I still have a problem after about 30 seconds of idling the gauge goes to zero and the check gauge light comes on. we have put a mechanical gauge at the filter port and there is oil pressure. Now the dealer wants to replace the ECM.

Somehow I do not think this is the solution to the problem. Does anyone have any ideas.

puller

 

[Bob4x4]

You are right puller changing the ECM will have no effect on an actual oil pressure issue. Eventually they Winn need to pull the oil filter adapter to fix the pressure issue

 

[puller]

Bob,
Why do they need to pull the oil filter adapter to fix the pressure issue?

 

[Bob4x4]

That is where all the pressure regulation and bypassing takes place. I have yet to see any problems that were an oil pump failure yet. The pump is very robust and is gear driven. The pick up tube is huge and the screen is a very large opening mesh

 

[puller]

Bob,



I understand if I had no oil pressure at all times but it only occurs when the engine is warm and when at an idle. I think that is why they are looking at the ECM. When they hooked a positive gauge to the top of the oil filter there is pressure within specs, same goes for the check at the oil pressure sender port on the drivers side of the engine, however the gauge and the computer says the oil pressure is zero. Most confusing.



puller

 

[mwilson]

The dealer has replaced the oil pressure sender with 3 different ones. I still have a problem after about 30 seconds of idling the gauge goes to zero and the check gauge light comes on. we have put a mechanical gauge at the filter port and there is oil pressure. Now the dealer wants to replace the ECM.



Somehow I do not think this is the solution to the problem. Does anyone have any ideas.



puller

Bob,



Shouldn't the dealer be able to check the gauge cluster??? 2006 clusters have given tach trouble at the very least.