Onan Genset Oil Pressure?

I have an Onan MDJF 15Kw genset and was wanting to see if anyone knew what the normal operating oil pressure should be? At 1800 rpms with no load it is showing just under 40 psi on the gauge. According to my manual it says it should be greater than 25 psi but doesn't say what the top range should be, only that if it drops below 13 psi it'll shut-down.

I have been having problems with it shutting down on the past couple of trips and I'm not sure if it is over temping or if it is an oil pressure issue. The indicator light on the flybridge console has stopped working ( yeah i know....it's on the list) and by the time someone comes up and says "oh by the way, you know the A/Cs off" the genset has now been down for 30 minutes or more. By the time I go below to check on it the temp is showing within normal range. I've replaced the oil pressure and temp switches, cleaned the heat exchanger, and, since our last trip out, installed a new thermostat (apparently the PO had removed the thermostat).

Sitting in the marina running with no load it shows 40 psi and around 160 degrees on the guages.

35 / 40 should be ok when it s hot. Have you tried running it under heavy load at the dock or anchored? Any steam or dry sound at the exhaust? If you don’t have an outlet on the FB, run an extension cord connect something like a light to troubleshoot

I have not run it under a heavy load at the dock but will try that this next weekend. I was just worried that the oil bypass valve might be sticking, especially since the only way to get to it is to de-couple the generator package from the engine.

You're right about the indicator light. There is an ac outlet about 2 feet away on the starboard side of the console that it would take me about 10 minutes to run a wire from for a new indicator light. I'll do that this weekend also.:D

Thanks

Alright, sitting at the dock running the entire boat (A/C, water heater, frig, lights, TV, etc) it holds at around 150 degrees and around 25-30 psi oil pressure after it has warmed up. It'll run like this for hours at the dock or cruising around the bay. In open water however, within 15 minutes the oil pressure will drop below 15 psi and it'll shut-down. I'm thinking it may be a problem with the oil pump pick-up and that once the boat gets to rolling a little it's pulling in air. Maybe a hole in the pick up cup or tube? The oil level is right at normal on the stick.

I was planning on dropping the oil pan this next weekend to check out this theory and have been getting the parts together that I know I'll need like gaskets and the gear cover seal. I was going to go ahead and get a replacement pick-up tube assembly but the part number listed in my manual (120-0601) is considered obsolete and even Cummins said they can't help with a replacement. I'm hoping that if the pick-up is the problem that there may be a work-around on replacing it.

Any observations, opinions, recommendations, .....snide comments?

The genset is an Onan 15 KW MDJF Series and I'm located in Pensacola, Florida.

Thanks
-Alan

While your at it change the impeller. It may no need it but if it’s been a while it wouldn’t hurt.

So it is motion, rocking and rolling related. Before dropping the pan I d check the wiring to the oil sensor. Loose wire? I m not sure how there could be a hole in the pick up tube. Are you sure there is enough oil? I d be tempted to pump out the oil and refill with the right amount to make sure the dip stick is accurate.

I'll double check the connections but I just put a new oil pressure switch on a couple of months ago. Since I'll have to drain it anyway, I'll see how close the oil volume I remove matches the quantity it is suppose to hold according to the manual.

After it quit on our trip out this past Friday I restarted it and sat in the engine room and watched the gauge. On start-up with it warm it would be at around 25-30 psi but would then start fluctuating as the boat rolled around in about 1-2 ft seas before finally kicking out at around 15 psi. I did this a couple of times with the same result. As we were heading back in the seas layed down almost flat within a couple of miles of the pass. At that point I started the genset back up and it ran non-stop until I shut it off at the dock about 2 hrs later after I was back on shore power.

Well, the pick-up tube was in like new condition, except for this....

Always good to get an answer, isn't it.

Quote:

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Originally Posted by jim rosenthal

Always good to get an answer, isn't it.

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Yep.:D