High oil pressure with an abnormally low temperature


#1

I have an auxiliary engine at work. It’s a Yanmar and it’s raw water cooled. (I work on a boat)

Today the gauges showed the oil pressure was maxed out and that the water temperature was abnormally cool. I shut the gear down, took a look around, checked the oil, the temp… everything was perfect…

I started it back up and evening read fine after that.

Electrical malfunction maybe?


#2

Are the gauges mechanical or electric or possibly even solid state electronic these days? And is the engine a diesel with a bypass filter?

A poor ground could cause one gauge to read high and the other low if the sending units were inverse in their resistance.


#3

They are mechanical gauges, diesel engine. I don’t know about any bypass filter.

A poor ground is ALWAYS a possibility being on a boat


#4

I hate to say it, but you’re more likely to find someone familiar with your problem on a marine forum.
You might even write to the engine manufacturer.


#5

Is the oil filter maintenance on schedule and it’s working correctly? You’ve checked the oil is clean as it appears on the dipstick, and the oil-level is spot on, right?

I can’t think of a reason why the coolant temp would be lower than normal and the oil pressure is higher than normal. Usually if one is hot or cold, so is the other. First guess, a gauge or sensor problem.


#6

How cold was the ambient temperature? If the coolant was quite cold on the engine block, I could see how this might be possible. The engine oil would be quite thick at a low temperature and cause the oil pressure to be higher than normal. I had a 1954 Buick with mechanical gauges for temperature and oil pressure. I started that engine at -15F. When the engine started, the oil pressure gauge would almost peg the top of the scale. As the engine warmed up, the oil pressure would drop slightly. However, according to the gauge, that Buick always had high oil pressure.
If your gauges.are electrical, then a.bad ground or electrical malfunction are possibilities.


#7

All maintenance is on schedule and spot on!

I mistakenly said they were mechanical gauges when in fact they are electric.

The normal oil pressure the engine runs is 50psi and the normal water temperature running is 140°F.

The more I think about it the more I’m guessing it’s an electrical issue.