06-30-2019, 08:03 AM
(This post was last modified: 06-30-2019, 08:41 AM by Tiara 38 open.
Edit Reason: Engine
What causes low oil pressure on port engine of Tiara38open cummings?
Low oil pressure can be be serious and caused by several things including bearings, oil pump, pressure regulator, etc. engine should not be operated with OP below spec. Cummins typically has 2 sensors on their engines, one for OP gauge and a low pressure switch that triggers an alarm if pressure drops below 10 PSI. If gauge is showing low OP and alarm is going off then you likely have a problem and should have cummins take a look. Otherwise likely you have a bad sender. A little more information such as what pressure readings are you seeing at given rpm and whether alarm is sounding will be helpful. Otherwise first step is usually to install a mechanical presssure gauge or swap OP senders from other engine to verify that an actual problem exists.
Thank you helping us: When the boat was running the port side was running at 700 rpm oil pressure was dropping below 12-14 psi. The alarm was starting to come on like a vibration, but did the alarm didn’t come completely on, if that makes sense. The starboard side was 18 psi at the same rpms. We did switch the op sensor from engine to engine, did seem to make a difference still reading the same. Any more advice would be very much appreciated.
Time to put a manual gauge on it. Even though you swapped the sender units it could be the gauge it self. Only way to truly tell is with a manual gauge hooked up.
If it still reads that low, time to get a good mechanic in there.
Sounds like your low op switch may need replacing. That chirping may be due to a soft spring that is letting the contacts bounce before the cut in level. But that doesn't mean you don't have a low op issue. Not being a Cummins guy I can't say whether that is normal for hot idle op. I would recommend you go onto boatdiesel.com, join and post. It's well worth the $25.00. Before you do however, a couple of things to do:
1) change oil filter to make sure it didn't collapse internally (unlikely but possible)
2) make sure the oil level is below the full line to rule out foaming
3) record Cold OP on each engine
4) record both engine hot OP at RPMs idle, 1000, 1500 and 2000 ideally with mechanical OP gauge. Otherwise note that you swapped senders when posting
5) get/post engine hours and HP rating
6) if possible record coolant temps with IR gun (thermostat housing) Hotter engine will run lower OP especially at idle. Also if you can compare temp readings of oil lines as they enter cooler.
7) any other pertinent info such as if the op suddenly dropped or came down over time.
The counter rotating gear always makes the one engine work a little harder and consequently heats up more so it could simply be hotter oil. No two engines will run the same OP. Never the less there are some really good mechanics on that site who will help you neck down probable causes or put your mind at ease. Best of luck.