Concerns over oil pressure indication on an ISB

[BlueLine]

We have a 1999 Winnebago with a Cummins 5.9 ISB engine, in a Freighliner chassis. My oil pressure indicator is in a Freightliner dash assembly, and my guage has no numbers, just an Arc with the word NORMAL. I have no idea what the real pressure is just that it fluctuates anywhere from the bottom of the N to mid range or R. During startup I feel comfortable with the indication mid scale around the R. After warm up the pressure decreases a litttle, but this is understandable due to the heating of the oil. However my nerves get tweeked a little when the needle starts a little dance in this lower range. Sometimes it will twitch upwards and hold for a minute or so, then drop down again. Steady speeds as when on cruise control seems to diminish the pressure reading. Since I have no idea what the real pressure is, I'm not sure what normal really is. Could I be having a regulator problem or pending problem, or can a regulator be adjusted up. I've read in the past of some regulator difficulties, but I can't relocate the posts. Also can I piggy back a true old fashioned mechanical indicator that won,t interfere with information going to the ECM. My engine temp reads comfortably low since the clean-out of the Charge air and engine coolant heat exchangers.

[Gary RVRoamer]

If its like my ISL, there is no actual pressure reading anyway. Mine always reads at the center of the gauge and my engine monitor gives a reading of 55 psi. But that's just the value the ECM puts out to show "oil pressure ok". I am told by the Freightliner folks that the oil pressure sensor on a Cummins just puts out an "ok" signal and not a pressure value, so the gauge shows an artificial position for "ok" and zero for "not ok". Ditto for the monitor - it reads either 55 psi or 0.

[BlueLine]

Thanks Gary, I guess I'll have to adapt to "All or Nothing" indications and let my ECM worry about it.

[chasfm11]

You don't have accept the dash gauges. We have VMSpc, an application that runs on a laptop. It has a special cable and translator box that allows the chassis (its called a controller area network or CAN) to talk to the computer.

We have a place on the dash where the laptop sits while we drive. I have the display customized so that I can see the oil pressure, intake manifold temp, engine temp and turbo boost. There are also graphs for things like engine load. It is fun to watch the load increase and the boost pressure go up with it.

In addition, the package captures and stores all error codes. That feature alone as saved me $1,000s in repair costs. You don't have to guess why the check engine light is on.

The package isn't cheap but we've used it for 5 years and 40K miles and wouldn't be without it.

[Triker56]

By VMSpc my ISB runs around 55-56 PSI driving 16-1700 RPM and around 20 PSI at idle.
Used the VMSpc for 8 years this month. It has been well worth the $350.

[BlueLine]

Thanks all for the replys, going to check into the VMSpc. I have two plug-ins, one in the engine compartment and one behind the dasboard display. I think I'll feel a little better with actual displays of what's going on.

[Hooligan]

FWIW, Your chassis should have the Kysor Medallion gauges. (All Freightliner built between Jan99 to May2000). On the gauge, just before the left edge of the "N" is 30psi, Straight up is 45psi and just after the right edge of the "L" is 55psi. Any pressure between is "NORMAL".
The VMspc is a much more precise and versatile display...

Hope this helps...

[J Walker]

My 2000 Freightliner with an ISB shows oil pressures in the range of 25psi to 62psi on my VMSpc. The dash gauge varies in its reading and I can't get a sense of what is normal from it. It appears to be very non-linear, and low pressures give very little deflection and then higher reading put the needle near the vertical normal. I agree with VMSpc being very helpful and cost effective.

[BlueLine]

I'm very appreciative of all your responses, and I see the general consensus is VMSpc. A unit has been ordered earlier this afternoon from the RV Upgrade Store and should be here by early next week. I'm not sure if their price on the USB cable was reasonable, so I'll opt for one from Wal-Mart if I need one. Not sure what the USB is for yet.

[J Walker]

Quote:

Originally Posted by gcipra I'm not sure if their price on the USB cable was reasonable, so I'll opt for one from Wal-Mart if I need one. Not sure what the USB is for yet.

If it is a USB extension cable there are lots of places you can get a good deal. If you are referring to the cable that includes the electronics (JIB) that converts the signal to be compatible with your computer, the "high" price is justified. It is the way Silverleaf makes their money since the software is free.

[BlueLine]

I'm assuming RV Upgrade was referring to a USB extension. They told me the unit included software and confirmed I had a 6 pin connector, which mine is, they also asked which tranny I had. The unit from them was about $352 including shipping. The lady said it was all I needed, I sure hope so.

[J Walker]

Quote:

Originally Posted by gcipra I'm assuming RV Upgrade was referring to a USB extension. They told me the unit included software and confirmed I had a 6 pin connector, which mine is, they also asked which tranny I had. The unit from them was about $352 including shipping. The lady said it was all I needed, I sure hope so.

The "cable" you are buying has a round connector that connects to your data plug under your dash, a JIB electronics box, and a USB cable that connects to your laptop.

[chasfm11]

VMSpc was designed some years ago when computers had serial ports. The USB cable that is being referred to is really a "USB to Serial adapter". I haven't seen a single laptop recently that still has a serial port.

I can tell you from personal experience that some of those USB adapters work better than others. We bought the USB adpater from Silverleaf when we first got VMSpc and it worked fine. When we upgraded the laptop to an HP with 64bit Vista, it would not work any more. I went out into the marketplace and finally found an adapter that said it would function in the Vista 64 environment.

In additional to the physical cable, there is a software driver for it. How that drive couples to the computer OS is important.

[Triker56]

[QUOTE=chasfm11;718652]VMSpc was designed some years ago when computers had serial ports. The USB cable that is being referred to is really a "USB to Serial adapter". I haven't seen a single laptop recently that still has a serial port. [QUOTE]

You havn't keep up with VMSpc lately.
The seial hook up is no longer. They finnaly caught up with modern day Laptops. And have been selling the VMSpc made for USB connections for a while now.

No more USB to Serial adapter needed.

Quote from RV Upgrades:
The new VMSpc eliminates the old-fashioned serial port and replaces it with a USB connection. It's tested with XP and Vista, and will also work with the upcoming Windows 7. There is no longer any need for a USB adapter, and you don't need to worry about which you start up first, the engine or the program.
It also supports the latest J1939 transmissions and engines, including the current Allison World Transmission. Their are new parameters available with some of the new engines, and additional diagnostic capabilities. The new VMSpc handles all the new stuff.