Oil Pressure Bouncing

[PuffinStuff]

Hello,

We have a 2012 R-29 with less than 200 hours on it and recently the oil pressure started showing wild readings while underway. At first, no pressure whatsoever (even though oil levels confirmed), then spiking to as much as 200, before settling down into a typical range of 60 - 70 at 2,800 - 3,000 rpms.

I've been told by other Ranger Tug owners that this is a common complaint with Yanmar engines and that it's simply a sensor, but I wanted to see if this was indeed common as I don't see a lot of threads on this topic on the forum. Going away for the 4th and want to be sure I'm not risking calamity by having it seen to ASAP.

Thanks,

Paul

 

[knotflying]

Chances are you have a bad ground to the ECU and for some reason it affects the oil pressure readings. The only way to know for sure that it isn't really bad pressure is to remove the sensor temporarily and install a mechanical gauge. There is a recent thread on this topic.

 

[Bruce Moore]

We experienced similar irregularities on our Yanmar powered R-29. Checked oil prior to every start. Always stayed within operating temperature. Spiking was sporadic and usually occurred at high RPM levels.

Bruce

 

[trailertrawlerkismet]

If it is not the sensor that Mike Rizzo refers to then a question I'd have is this: what has changed recently that may be causing the fluctuations? Has the oil just been changed? was the correct oil weight and or grade followed? There have situations of the wrong oil being used where owners have experienced oil pressure problems. Just a thought.

Jim

 

[Hydraulicjump]

I am a scarred veteran of this problem and other mysterious alarms. I replaced the oil pressure sending unit and things got better for a month and then came back. In the end, it was as noted before, a bad ground for the ECU. Such drama for such a little issue, but it turns out that Yanmar did not build a lot of tolerance for voltage drops on the ground into their ECU. With time, corrosion and aging wires increase resistance and the ECU starts acting goofy. I would start by vigorously cleaning the grounding buss and all terminals on your batteries, especially the engine start battery. If you can locate the ECU ground, clean that contact as well. If the ECU is grounded to the grounding buss, put that wire right on top of and in clean contact with the ground to the engine block. Hopefully this will take care of the problem, but one can't rule out a bad ECU. Pressure fluctuations like that, as I have learned, defy the laws of physics in an engine that is running smoothly and has a mechanical oil pump.

Report back. Others are having this problem as the wiring on their grounding wires and connections grow "tired". I am told by Yanmar that they are trying to come up with a fix.

Check in with Andrew and he can guide you.

Jeff

 

[LADYBUG TOO]

The oil pressure sender is an analog unit that connects directly to the interface module. It is the only sensor that survived our lightning strike. That being said the grounding issue and a low tolerance for voltage drops is a fact of life for the 6BY Yanmar engines. Our current issue is glow plug alarms triggered by low network voltage. To compare battery and network voltages turn your key on but do not start. The network and battery data are available on the display. It is a good tip off to a ground issue. We have set one of our optional screens to display network and battery voltages. We are seeing almost 1.0 VDC difference between the two so when we start the ECU sees excessive glow plug voltage drop and alarms. After the engine stabilizes and the alternator has brought network voltage up, the alarms clear. The suggestions regarding grounding a right on. We have found and corrected several weak points but one little gremlin is escaping us.

Pat
Ladybug, Too

 

[The Bud's Tug]

Hi Paul;
We have the same issue with our Yanmar. Andrew has suggested using jumper cables ...connect the black to the ground at the block and the other end to the negative at the engine battery. Cover up the "reds" so they do not come in contact with metal. He suggests running with it to see if it improves the read-out of oil pressure. If it does, then it is a bad ground and, as stated in this thread, start by cleaning the ground connections ...engine battery included. If not, then it could be a faulty sensor, which Yanmar has had.
I have inquired and the cost of a sensor is approx. $200 CDN.

I find that the oil pressure will eventually settle down to a proper reading of approx. 44 psi if I back off the throttle a little. Then I can start to inch up the rpm again. Does not seem to be any pattern as to when the reading will disappear altogether or just shoot up erratically.

I am going to try the grounding and see if that helps the readings before replacing the sensor.

 

[assignment]

You can check the ground and the condition of all associated wires - which should and probably is part of your routine. We had a similar problem which was diagnosed to a faulty oil pressure switch and sensor module. We had about 200 hrs...Yanmar took care of all repairs under warranty. Might want to give that a try too.

 

[aginglawyer]

I have had this problem before and again this morning en route home. I was told by my mechanic when it first happened that the sensor itself is just about a pinhole within the engine to sense the pressure and that it takes very little to plug or partially plug that opening and then the pressure bounces all around. Today I ran the rpms up to 3600 and then back low and then back to my operating range and that seemed to clear it up (for today).

A slightly different issue occurred last fall with the oil pressure reading dropping to zero and the engine refusing to go over 2200 rpm, what is known apparently as the "safe range" which, of course it is not, but it does allow you to get to the nearest mechanic. This time the sensor was fully plugged and got no pressure. Of course, before operating in the "safe range" I checked below and no oil was spraying and the oil level was just fine.

I think Yanmar (or perhaps BMW, the manufacturer of the engine) has put a pretty crappy part in this engine.

Allan

 

[knotflying]

I have been told, but can't verify the results, that the fix for the clogging hole on the oil sensor is to enlarge the hole slightly.

 

[Hydraulicjump]

Hey all, my schizo oil pressure reading (with ear piercing alarms) issues returned this past weekend...15 miles outside the Golden Gate. I had a good long talk with Michael Angland at Yanmar National in Georgia (great guy to work with) and he is pretty certain they have figured out how to resolve this particular problem. It involves replacing the grounding wire for the oil sensor unit and its connection to the wiring harness, as well as a necessary software fix to one of the controllers. So if you are having this issue get a hold of your Yanmar mechanic and tell him or her (are there any female Yanmar mechanics?) that Yanmar national in Georgia has worked out a fix. I am told that it takes about an hour to install, but they will want to put a mechanical oil pressure gauge on just to be certain. That requires taking off the beauty plates on my boat.

Fear not, it is highly unlikely that the oil pressure craziness you are reading on your screen reflects actual oil pressure in your engine. It's just darn hard to ignore the screaming alarms....

And for those of you who have not had this problem, it may crop up in the future as your wiring harness ages and resistance increases. Interesting that this issue only appears on Rangers and Hinkleys, according to Yanmar. This may be because our boats are so fabulous the electrical system is overwhelmed by our awesomeness. Or something like that.

 

[knotflying]

I have two pictures of the culprit wire with an arrow pointing to it.