Low Oil Alarm

[Autocar]

The last two days Ive had a every now and then problem on my low oil pressure alarm on my 1987 Autocar. It has a NTC300 Cummins engine. Where I was working I backed in beside a giant chicken house a hundred yards long [ two story ] and on my drivers side was a woods. Pretty warm and wondered it that might cause the problem. Flip the P.T.O.on and high speed idel [ 1000 RPM ] and load logs when I got back into the truck it was buzzing. Take off and drive about a hundred yards and it went off. It did it three times that day, on every return trip to the same spot to reload. Yesturday Iam loading in another location with a slight lean because I was setting in a side ditch. Same thing get loaded and it is buzzing about 75 yards down the road and it is fine, rest of day ok. Oil level is fine and pressure is running 35/40. Is the sencer going bad or is it something thats needs looked at soon. Thanks for ant ideas you may have.

[Gary_C]

I had a similar problem with my 1998 International with a Cat 3406B and after checking sensors, etc, I sent it to a shop and they pressure checked the cooling system and there were coolant leaks all around the sleeves. Needed an overhaul at 850,000 miles.

Ironically after the overhaul and a new oil pump, it had low oil pressure again but we traced that to a faulty machining job on the casting of the new oil pump.

Other causes could be a cracked/leaking oil pickup tube and I was told leaking engine brake assemblies under the valve covers. Pull the valve covers and look for excessive oil squirting from each engine brake assembly.

[grassfed]

If the pressure is 35/40 while the alarm is going off it sounds like a bad sensor or the wire going to the sensor could be grounding somewhere between the alarm and the sensor. I think that most of the time warning alarm sensors allows the wire going to it to ground when the pressure drops ("make" contact). If the sensor works the the other ("break contact") then a loose/corroded connection could cause a false alarm. This all depends on the actual oil pressure while the alarm is sounding. The first thing I would do is to check the wire to the alarm sensor and if it looks good I would check the oil pressure gauge or put on a accurate gauge. If the gauge is good and the wires to the sensor is good then I would start looking at the things Gary C mentioned.   

[Gary_C]

One other thing I forgot to mention. On my engine the alarm sensor is thru the engine control module while the gauge sender is separate. So you may have two systems monitoring oil pressure. We checked the gauge location with an accurate gauge and it was right on. But we still got alarms at pressures above what should have been OK pressures.

It was not the gauges anyway.

[Autocar]

Hopefully I can look at it this weekend. Do any of you know where the oil sencor is located on the block. Plan is to unhook the oils sencor wire and try to track it back to the alarm. I  hate wiring problems it is darn near impossible to track wires under the dash in those bundles.

[snowstorm]

ih and westernstar have numbers on there wires. dose your acar?

[Autocar]

Snowstorm if there's numbers on them I can't see them but thats not saying much eyes arn't what they use to be. I have to look at standing timber tomarrow but hope to get time to look for the problem. Been running steady every day this week and haven't had the alarm in two days.