My Yanmar engine oil pressure gage is going crazy

[dencarst]

My R27 Yanmar oil pressure gage started to fluctuating between 60lbs to 250lbs pressure and then goes back to normal pressure. This all started when we went fisherman terminal and has been erratic since then. The engine has 460 hrs on it. Most of the time the readings are normal pressure.

Tug of My Heart 11
R27

 

[walldog]

Dennis,

The sending unit for the instrument gauge is probably defective. We had ours changed out just before the warranty expired. Your oil pressure is probably ok as the alarm is taken from a different point. Our alarm never sounded during the wild fluctuations of the gauge.

 

[Dale777]

Dennis,

On my previous R27 with Yanmar 180, I had similar symptoms (wildly fluctuating from 45-95 at higher RPMs, but steady and normal at lower RPMs). Also, the oil pressure alarm never sounded. After the oil pressure sending unit was replaced, then all was back to normal.

 

[aginglawyer]

This seems to happen regularly and is probably a function of a 25cent oil pressure sender protecting a $25,000 engine. There are lots of theories on this including ground wires, bad senders, pinholes that are too small, cheap rheostats, senders that are not up to the marine environment and simple witchcraft. I have had the problem twice with the sender doing what yours does, i.e., fluctuating all over the place, and, the second time, setting off the alarm for low pressure and limiting rpm to a 2200 rpm in "safe mode," whatever that is.

There has never been an oil pressure problem on my boat but it is a good idea to look below, if the reading is low, to see if there is oil spurting somewhere. At the same time, if the readings are wonky, keep an eye on the temperature reading; Oil problems will almost always make the engine temperature rise fairly quickly. That's the time to shut down ASAP.

Will Yanmar provide a better oil sensor? Don't hold your breath.

Factory, any comments?

 

[Hydraulicjump]

See this and many earlier threads on this issue. I just had the "fix" done and it appears to work.

viewtopic.php?f=5&t=5153&p=37321&hilit=Oil+pressure#p37106

 

[kim&tim]

We are on our third oil pressure " not sending " unit!!! Same symptoms as noted by all in the prior posts....with the same result after each replacement......works fine for a while and we think the problem is resolved. However the fix is only temporary each time. Maybe yanmar needs to step up based on the fact that this issue seems to be common amongst all of us?

 

[Hydraulicjump]

I can't speak to everyone's problem here, but read my earlier posts on this. Just replacing the oil sending unit usually does not work long term. Your mechanic needs to contact Yanmar national to get a fix. Michael Anglund helped me out and he is great to deal with. You need to:

Replace oil sending unit
Replace connection to the harness (to deal with voltage drop on grounding wire)
Replace controller (see picture from knotflying)
Then, as I discovered yesterday, the mechanic needs to recalibrate the oil pressure alarms so they are not so sensitive (not sure how this was done).

I had this done yesterday and everything behaved well, so far. But I think just replacing the oil sending unit alone won't work (I did that and it worked for about 6 weeks). It is a "sensitive" system that can be made to be less so. Hang in there.

 

[Andrew Custis]

I think Jeff was able to sum it up quite good for us. Yanmar has a sender that isn't the best but it has never proven to be any sort of problem other than a nuisance. If you have this issue, I would suggest contacting Yanmar directly to see if they can refer you to a dealer for a fix. Recently I was able to spend some time with the Yanmar folks and they were very interested in finding a long term solution. I suspect there will be a service bulletin very soon.