Community Forums

AustroTom · 08-24-2022, 06:53 PM

Hello All,
I think I've got gremlins in my system again.
Lately everytime I stop the rig (almost to the spot of standstill), the oil pressure needle drops to zero, the buzzer and light comes on, and as soon as I'm completely stopped (and or get moving again), it jumps right back up to 50 lb of pressure.
Would this be a problem in the electronics, or simply low oil warning?
Please help.
Thank you,
Thomas

Skip426 · 08-24-2022, 06:56 PM

What engine and chassis ?

Cat /Freightliner ?
Cummins Spartan ?

AustroTom · 08-25-2022, 07:07 AM

oh sorry, 2004 Newmar MountainAire with a 400ISL Cummins.

Skip426 · 08-25-2022, 10:15 AM

Quote:

Originally Posted by AustroTom

oh sorry, 2004 Newmar MountainAire with a 400ISL Cummins.

Thanks for the additional info ; please consider setting up a signature line with your coach info so it automatically appears below your post ; as mine does below this one.

I'll assume your coach is on a Spartan chassis , most with Cummins are .

Now , questions .
I believe the ISL is available with either a single stage exhaust brake or a multiple stage engine brake .
Which brake system is your engine equipped with ?
If your engine has the engine brake .
During the slow to a stop , was the engine brake in use ?
If it was ; does the same loss of oil pressure occur if you come to a stop without the engine brake on ?

Have you ever had the engine go into " Protect Mode " or " Shut Down " when the pressure shows low?

The reason for the questions .

The engine brake system uses oil pressure to de-activate the engine valves to provide the brake action.
Members have reported the engine brake system leaking oil ( under the valve cover so not visible ) and causing the low oil pressure you describe.
When the engine comes to idle ( or throttle is applied ) the ECM stops the engine brake operation and any oil pressure loss in the system stops .
So if you don't notice the pressure loss with the engine brake off , during stops , the system needs to be checked out by qualified personnel.

AustroTom · 08-30-2022, 11:19 AM

I'm sorry, I was away for a while.
Yes, it is a two stage engine brake activated by the throttle pedal release.
I can't rcall that the engine ever shut down (or protect mode).
I've had some occations where the rpms were too high for the ebrake and the light and buzzer came on. Could there have been some damage to the system due to that situation?

jacwjames · 08-30-2022, 07:13 PM

Is this a dash gauge reading?

I use a Silverleaf VMSpc to monitor my engine and transmission. Much more accurate then my gauge.

AustroTom · 08-30-2022, 07:48 PM

yes, dash reading

jacwjames · 08-31-2022, 07:54 AM

When I first bought my coach the dash oil gauge was not reading right, I took to the Cummins shop for a complete service and inspection and asked them to look at it. They said my oil pressure was fine but couldn't fix the gauge problem.
Soon after I got the Silverleaf VMSpc.

Is your Check Engine Light coming on? If the CEL light isn't coming on it may mean the ECM isn't seeing low pressure.

Not sure on you coach but mine has a separate sending unit for my dash gauges versus what the ECM uses.

AustroTom · 08-31-2022, 08:52 AM

Yes,CEL comes on but also goes out immediately with the low oil warning when moving again

AustroTom · 08-31-2022, 08:53 AM

BTW: I set up a signature with coach info but it isn't putting it on my posts for some reason

AustroTom · 08-31-2022, 08:54 AM

AND, now it just DID! :-))

Skip426 · 08-31-2022, 10:09 AM

Quote:

Originally Posted by AustroTom

AND, now it just DID! :-))

Well , look at you ; typing and posting faster than the site computer.

Gary RVRoamer · 08-31-2022, 01:31 PM

Are you aware that the oil pressure gauge is a fake? The ISL reports engine oil pressure as either OK (adequate pressure) or none, i.e. it's a binary condition. It's a single bit on the engine data buss, which is read by the gauge cluster module and converted to whatever it chooses to display, apparently in your coach 50 psi for "adequate" and "0" if not. The warning typically comes off the gauge. Since the engine isn't reacting by shutting down, I'm guessing the ECM is seeing an OK on the data buss. That makes me think the problem is in the instrument panel module or the connection to the gauge.

2004 Mountainaire diesel pusherss were available of either Spartan or Freightliner chassis, so need to know which to get more detailed.

AustroTom · 08-31-2022, 02:41 PM

Very great info! The gauge shows 0-50-100 with 50 being "normal" I'm guessing.
Chassis is Spartan MountainMaster tag
Gosh, now I have to edit my signature already :-)