battman

Yesterday I changed the oil in my '05 2500 5.9. I put in the correct oil in the correct amount. Now my oil pressure seems to fluctuate a lot more than before I changed the oil. It stays in the 'acceptable' range and comes up to 45-50 psi when at rpm.

It just seems to me it always stayed around 40 psi before I changed the oil.

Any ideas?

For what it's worth I used Mobil I Synthetic 5W-40 Diesel Oil that meets the CI-4 standard which is what the owner's manual recommends. The filter is Wix. There are no leaks that I can find.

StealthDiesel

The in-dash factory oil pressure gauge is a fake. Ignore it completely unless it is reading zero with the warning lite on.

If you want to prove this, unplug the sensor for the fake gauge. It is above the engine mounted ECM on the driver's side.

battman

Thanks for the information. I am going to try disconnecting to see what happens.

DWeiler

Cold start up mine runs 80psi+,hot idle is 18-20psi,highway is 45-50psi at 65MPH---this all read from the port/sender at the oil filter.DW

battman

DW, thanks for the reply.

I know oil pressure usually changes with the temp and rpm. This wouldn't have been a question except my oil pressure never fluctuated until I changed my oil. Your numbers seem to be about I'm seeing on my gauge.

DWeiler

Everything seems cool than,,,,,,Maybe a thinner oil than before-----I run 15w40 AMSOIL most of the warmer months then switch to 5w40 in late Nov for the winter months when temp drop to -35-40ish up here in Alberta.DW

StealthDiesel

Battman, you are missing an important point. The in-dash factory oil pressure gauge is a fake.

The ECM is controlling that "gauge" to read normal readings based on rpm, coolant temp and whatever else.
It is NOT reading oil pressure. There is no oil pressure gauge sensor, it is only a switch as per the Dodge parts manual.
The fact your in-dash oil pressure gauge is reading differently now has nothing to do with oil pressure.
It's likely cooler now than the summer.

If you unplug the factory oil pressure gauge sensor/switch and start the engine, the in-dash gauge will read normal for about a minute then it goes to zero.

DWeiler has an aftermarket oil pressure gauge connected to the oil filter head, as do I.
My oil pressures are identical to DWeiler's.

Do yourself a favor and connect a real oil pressure gauge of some kind to the filter head and then compare it's reading to the in-dash oil pressure gauge.

You will see what a crock the factory oil pressure "gauge" really is!

47Dodge

Yup! The crock oil pressure gauge was almost a deal breaker for me when I test drove my 2005 at the dealership. The salesman and I went for a test drive. Loved everything about the truck and looked at the gauge and thought *** is going on here. Kept and eye on it the whole time test driving it and was gonna run as fast as I could because I thought it had some serious issues. After talking to a friend of mine and reading up on it I realized everything was ok.




47

battman

Stealth, where did you get your gauge? I'd like to install one to get a true reading.

StealthDiesel

I run the basic 90degree sweep electric oil pressure gauge and water temp gauge from Autometer.

The electric oil pressure sender is connected to a 24" SS braided hose to the 1/8NPT port on top of the oil filter head.
The electric sender will not survive if mounted directly to the Cummins engine due to the vibrations.

For the water temp gauge, I drilled and tapped the cast iron thermostat housing.

I also have an Autometer pyro, boost and the pricey Autometer 270degree sweep 0-30PSI low side fuel pressure gauge.

I installed these gauges 8 years ago with no issues other than the oil pressure sender that failed after a few days when mounted directly to the engine.

DWeiler

I must of lucked out as I did not know the vibration would kill the electric sender there.I have to run my pressure reading from a tee about one inch above the port due to my Amsoil bypass taking oil out of the port to the remote filter so it is not threaded into the port itself(Thanks for the heads up JOE-Stealth Diesel).I did not like how close it was to the exhaust manifold though, so I run a 6 inch,high temp, thermal spark plug boot protector over the tee and sender just in case heat might shorten the life as well.DW

rockcrawler304

I also run the Amsoil bypass filter and I have been thinking about doing the real gauge like you did. What are the psi numbers you are seeing with your gauge plumbed in like this?

DWeiler

right here,backed up by Stealth Diesel too.DW

rockcrawler304

Thanks!! I over looked that

battman

Thanks for the information. This looks like something I definitely need to do.