Oil Pressure Alarm at Idle!

Digital Boy · 10-18-2006, 09:47 AM

I have a 1998 MM chassis with a Cummins C8.3 mechanical engine. Most often, after being on the road and coming to a stop in traffic a rest area or a campground, I get a low oil pressure light and alarm. The needle hovers very near zero.

At start up, the needle jumps quickly to 50 then on the highway it stays between 30 and 35.

I check my oil level frequently and add 1/2 quart or so as needed.

What do you think? A bad sending unit? Or something more sinister?

I'll have the rig at the Ocala Cummins shop in a week or so. But, I want your opinions.

Digital Boy · 10-18-2006, 09:47 AM

I have a 1998 MM chassis with a Cummins C8.3 mechanical engine. Most often, after being on the road and coming to a stop in traffic a rest area or a campground, I get a low oil pressure light and alarm. The needle hovers very near zero.

At start up, the needle jumps quickly to 50 then on the highway it stays between 30 and 35.

I check my oil level frequently and add 1/2 quart or so as needed.

What do you think? A bad sending unit? Or something more sinister?

I'll have the rig at the Ocala Cummins shop in a week or so. But, I want your opinions.

**RV Wizard** · 10-18-2006, 11:33 PM

Lew, how many miles or months ago was the oil changed? What oil are you using? How often are you having to add oil?

Digital Boy · 10-20-2006, 03:44 AM

The oil was changed last February or about 6,000 miles ago. Cummins Power South will service the coach on the 31st.

I use the recommended 15W40 oil.

I've only added about a quart in the last 6 months.

Further, I've just heard from a friend that there was a problem with a batch of oil sending units over the last few years. Mine was replaced in '03.

I guess the Cummins/Spartan shop will just replace the sending unit and we'll see what happens.

BIGRED1 · 10-20-2006, 07:27 PM

The oil pressure at idle in my '00 Monaco Diplomat with the 315hp 8.3L ISC is 30 lbs. and its' 60 or higher at normal road speeds.

clubmed98 · 10-21-2006, 02:08 PM

i have same engine and it will drop to a low enough pressure to just barely trip the alarm when hot and idled..just barely touch throttle and it goes away..probably a quirk of the engine

Digital Boy · 10-21-2006, 05:12 PM

Clubmed98,

You exactly describe the symptoms my coach exhibits. I now believe it is a failure of the oil pressure sending unit and will have it changed on the 31st.

clubmed98 · 11-03-2006, 02:10 PM

lew did the replacement solve the problem??

Digital Boy · 11-03-2006, 02:23 PM

This past week Commins Power South determined that the sending unit was bad - my initial suspicion.

The technician ran a pressure test to confirm that the oil pump was working . . . and it was.

The sensor is on order and should be in this coming week.

clubmed98 · 11-03-2006, 04:34 PM

be curious how works out

Jerry Wessel KA8MBK · 01-18-2007, 11:43 AM

Cummins has had a problem with oil pressure sensors. For several years they installed a switch instead of a pressure reading sensor. I believe it conered some 2000-2002 engines. When people had a problem they put in the switch. You did not get a accurate reading. It just told the ECU that there was oil pressure, not how much. I have a 2000 Tradition with the 315 ISC. I have a road relay from cummins and it does not agree with the guage. ON many of the forums this has been discussed.