Poor Engineering 2004 Dodge Oil Pressure

[Wayne M.]

Hi all, I recently got wind of this alarming lie over on another thread (I must have been under a rock back in march). I would like to know if anyone has or can get a wiring diagram for a 3gen and PM me? I would like to study it, and until I can get a cd FSM I will be in the dark :{ . I now am considering a second O. P. gauge- and I do my own maintenance. I would like to know weather our engine has 1 or 2 sending units? and how many wires go to the sender?

 

[nickleinonen]

The theory is that by the time you lose enough oil volume to drop the pressure down to 7 psi you've already damaged the engine.

internally, there would be no major internal engine damage in the amount of time before you could shut it down... you would wear a little on the rod and main bearings, but nothing that would require a rebuild i feel. the turbo might get fubared, but much easier to change a turbo than pull the engine to do in new lower end bearings [cam brgs would be fine i feel]...



oh, and if going with electronic oil pressure gauges, get a quality piece. i had a cheapo parts house one and the sending unit has slowly been crapping on me. it never read higher than 70lbs or so, and saturday it decided to start showing me 10lbs pressure at idle, so out came that gauge and a temporary mechanical gauge i installed under the hood. with the engine warm, i had 30lbs idling and just about 85lbs at 3500rpm [80lbs at 2500rpm]... i think i am going to end up popping for a pair of $PA's if i can get somewhat a good deal

would like to know if anyone has or can get a wiring diagram for a 3gen and PM me?

http://www.dodge.com/bodybuilder/ <- go here for 04 and 05 factory wiring diagrams right from dodge...

 

[jwduke]

I'm going to fo the gauges by the A pillar, does Issopro, make a oil pressure gauge that matches?

 

[rbattelle]

oh, and if going with electronic oil pressure gauges, get a quality piece. i had a cheapo parts house one and the sending unit has slowly been crapping on me.

You should see my Isspro. I really like Isspro and think they make a quality product, but something's been "wrong" with all 3 of the oil pressure gauges I've got from them. I can't figure out if the sending units are going bad or they're just susceptible to the electrical noise under the hood. Needle bounces all over the place and frequently reads WAY too high (never too low, though).



-Ryan

 

[nickleinonen]

well, my mechanical gauge is telling me a bad story too... it seems now i am down to about 18psi hot idle when i originally had about 22psi hot idle [that was with the electric gauge though] with the 0w40 in the sump... that is measured off the top of the filter pad. . so i am guessing another 5psi off that 18psi would be close to what the main gallery is seeing... i can't smell any fuel in the lube oil, but i could have swore i am up a little on the oil level [maybe just the paranoia kicking in]

i am fine with the 18psi idling hot, but the 4 lbs drop bothers me. i need to keep an eye on this one [and see if i can get the oil lab at work to burn a sample for me]. . i might get a mechanical pressure gauge for in the cab now [the $PA's are too expensive in canada] i should have little trouble finding an autometer ultralite series mechanical lube oil pressure gauge in the local speed shops around [good price however might be hard to find ]

 

[rbattelle]

well, my mechanical gauge is telling me a bad story too... it seems now i am down to about 18psi hot idle when i originally had about 22psi hot idle [that was with the electric gauge though] with the 0w40 in the sump... that is measured off the top of the filter pad. . so i am guessing another 5psi off that 18psi would be close to what the main gallery is seeing... i can't smell any fuel in the lube oil, but i could have swore i am up a little on the oil level [maybe just the paranoia kicking in]

i am fine with the 18psi idling hot, but the 4 lbs drop bothers me. i need to keep an eye on this one [and see if i can get the oil lab at work to burn a sample for me]. . i might get a mechanical pressure gauge for in the cab now [the $PA's are too expensive in canada] i should have little trouble finding an autometer ultralite series mechanical lube oil pressure gauge in the local speed shops around [good price however might be hard to find ]

Nick, I can't believe you're serious about this. 18 psi hot idle is about what I see at the filter head and I don't worry a bit about it. You can't assume that your old electric and your mechanical are even completely calibrated so the 22 psi reading you were getting from the electrical could be off by 2 psi and the mechanical could be off also by 2 psi.



Factory spec is 10 psi hot idle and 30 psi at 2500 RPM. Your oil pressure readings are consistent with mine (when my sending unit is behaving).



-Ryan

 

[nickleinonen]

Nick, I can't believe you're serious about this.

the lower pressure doesn't bother me [i'd be ok with 15lbs idling with the hours i have on the engine now, and 10lbs when i have 3-4x the hours i have now]

but it is the pressure dropping that bothered me [... all the talk about oil being diluted with fuel from failing injectors sorta scares me]... i've got some 15lbs hobbs switches that i think i might wire up to an idoit light until i can get myself a mechanical gauge to put in the cab.

 

[Hoefler]

For the top of the line route you could go with one of these gauges Set the alarm led to flash at what ever pressure you want and also set the external alarm output to sound a buzzer.



Or for a more low cost method just add a warning lamp sender and 12v lamp inside.

You can go to any good auto parts dealer and look in their "Standard " catalog under pressure switches and pick out one for about any pressure. Then you can hook a light, buzzer, bell or what ever to it.

 

[rbattelle]

the lower pressure doesn't bother me [i'd be ok with 15lbs idling with the hours i have on the engine now, and 10lbs when i have 3-4x the hours i have now]

but it is the pressure dropping that bothered me [... all the talk about oil being diluted with fuel from failing injectors sorta scares me]... i've got some 15lbs hobbs switches that i think i might wire up to an idoit light until i can get myself a mechanical gauge to put in the cab.

Well, I think you're fine. If you're gaining oil on the dipstick I think it's your imagination. It seems to me that these injectors fail BIG, not gradually over time. We usually hear about some poor soul who was driving along and then BOOM! there goes an injector.



-Ryan

 

[Wayne M.]

Where are you guys taking pressure from? I thought I read earlier in this thread or another that someone was concerned about tapping in at the filter head/cooler due to possible hammering from the nearby oil pump. If I install a gauge, I'm gonna tee off the OEM switch- if I ever find it! tho I havent look too hard.

I'm hearing about way too many sender/ gauge reading concerns here.

In a recent fleet of trucks I was involved with, there was a braided -4 line off the main rifle going to a generic electrical O. P. sender and sometimes a Kysor switch on the bulkhead. These senders lasted the life of the truck and always worked well because I believe there was "smooth" pressure there. In the current fleet (Mack LE) we have a typical Mack setup- a braided line from the engine to a small manifold in the cab holding electrical switches and a synflex line to a mechanical gauge. The Vmac (like cummins celect) system has an O. P. switch just for shutdown protection.



In my old '92, I had isspro gauges and they were quality units, except for the boost gauge. I exchanged it twice and always had a stuck needle under light boost.

 

[rbattelle]

Where are you guys taking pressure from? I thought I read earlier in this thread or another that someone was concerned about tapping in at the filter head/cooler due to possible hammering from the nearby oil pump. If I install a gauge, I'm gonna tee off the OEM switch- if I ever find it! tho I havent look too hard.

I *think* (I always get this backward) the ports atop the filter mount are POST filter, so I would expect that to dampen out most of the pressure fluctuations from the oil pump. I'm not entirely clear on how much fluctuation might be expected from the particular pump style on these engines.



I, too, intend to relocate my oil pressure sending unit to a tee fitting off the main oil galley. But other projects keep getting in the way so I've been waiting for Nick to do it and just tell me what I need.



-Ryan

 

[jmtandem]

oil pressure???

Rbirdy,



I feel for you as you are probably sick about the problem, I would be. However, having said that, the oil pressure gauge measures pressure not quantity and as long as there is any oil it will read pretty close to normal. The gauge does not read low oil levels. While I don't necessarily care for virtual gauges it is not really a Dodge engineering problem if your mechanic doesn't tighten the filter sufficiently. Not tightening the filter is an maintenance problem. It is doubtful that any guage would be quick enough to tell you of the problem when you lose all the oil very quickly.

 

[Wayne M.]

"While I don't necessarily care for virtual gauges it is not really a Dodge engineering problem if your mechanic doesn't tighten the filter sufficiently. "



This is true, but I don't like being fed simulated into or lied to. I just know that if the filter came loose enough to bleed dry quickly, or if the oil level were low enough (you can see cavitation with a good gauge) you could pick up on it and hit the key- just to be safe even. There isn't a chance with this system!

 

[nickleinonen]

the factory oil pressure switch is on the left side of the engine [drivers side] somewhere between the ecm and the fuel filter canister. . i haven't tried to figure out what the switch has for threads [although i know it has an o-ring seal, so metric or sae straight threads]



the service manual states the top of the filter pad is the location to put a mechanical test gauge on so it should be pretty good there. . i too want to get the oil pressure off the gallery so i can use the port on top of the filterpad for oil temp. .

 

[JHardwick]

i haven't tried to figure out what the switch has for threads [although i know it has an o-ring seal, so metric or sae straight threads]

Prolly the same stuff I used for fuel on my sprinter, look here ... ... ... ... .



a lot of -AN stuff

 

[rbattelle]

the factory oil pressure switch is on the left side of the engine [drivers side] somewhere between the ecm and the fuel filter canister. . i haven't tried to figure out what the switch has for threads [although i know it has an o-ring seal, so metric or sae straight threads]



the service manual states the top of the filter pad is the location to put a mechanical test gauge on so it should be pretty good there. . i too want to get the oil pressure off the gallery so i can use the port on top of the filterpad for oil temp. .

Okay, I've decided to proceed with this little project. I'm going to order a new oil pressure sending unit so I can see what the threads are without having to pull mine. The sending unit costs $10. 53 from dodgeparts.com.



-Ryan