Yanmar 4BY2 Oil Pressure

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rpmerrill

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Fluid Motion Model
C-28
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BAY RANGER
What are the expected oil pressure ranges I should see during operation?

The "gauge" on my engine display only goes to 100 psi. (With digital numbers shown below.)
I have noticed during the time after start up that the oil pressure goes above 100 for 5-10 minutes and then settles down to something like 80 psi at, say, 2500 rpm. On the gauge display the needle is pegged at 100 but the digital goes up to 110 to 120 psi.

Is this normal and just a part of the warm up process?
 
When the oil is cold it is thicker and the pressure is higher until it warms up. To me your pressure is on the high side , but wait and see what others with the same engine say.
 
Your pressure does seem to be on the hi side. As Irish mist said it will drop once warmed up. Your high pressure may have more to do with software programming than actual pressure. The pressure is read via the sensor which will operate at varying ohms and then that is sent to the ECM and it converts it to a pressure reading. So your problem could be the sensor or the software. There has been a history of erroneous readings and there was a service bulletin on this. It requires a dedicated ground to the sensor and then an upgrade on the software. The yanmar advisory is yasa2014-005-M. After the upgrade you should read - at 4,000 RPM between 51-73 and at 1000 RPM between 20-51
 
Your starting oil pressure is too high. But I had the opposite problem, which was traced to the ECU. It may be that this is another manifestation of the ECU problem. You can find a copy of the factory service advisory in my album here:

gallery2.php?g2_itemId=38756

Check all of your ground connections. I have been amazed at the number of goofy things related to weak ground connections..
 
Yes, according to a tech guy I have spoken to at Mack Boring is that the biggest culprit on these engines is poor grounding. Bad grounds equal erroneous issues.
 
Hi

I had this problem a couple years ago The Yanmar dealer tried to fix it and Yanmar required them to send it back to Atlanta Georgia with the ECU and Pressure gage and after several months the dealer gave up and put a new unit in but the only we had had not been calibrated now it reads low or not at all. So much for Yanmar Service.

Dennis
 
I looked at the Yanmar bulletin and the posted photos.
Then I dug into the 4BY2 service manual on-line to locate the sender and study the wiring diagram.
High resistance at the sender (or in the ground) causes high pressure readings.

Off to the marina to do a little peeking and poking.
Stay tuned.
 
OK, back from the marina.
It took me a while to get the engine cover off. Ugh.

(Will a socket dropped into the forward bilge eventually roll back to the aft bilge?)

I continue.
I disconnected the terminals on the oil sender. Not real dirty.
I measured the resistance of the sender at 9.4 ohms. Right within spec.
Strangely enough, I was able to start and run the engine with the oil sender disconnected. No alarms.
I measured some ohms across the sender at idle, 41 ohms. Translates to 22 psi on the linear plot of the sender specs.
I ran the engine up to 1500 rpm in neutral (cold engine) and read 148 ohms. Translates to ~105 psi by extrapolation.
That one seems high but the engine was still cold.
I think I need to get everything heated up and try it again.
Stay tuned for that.

In the meantime, I'm nervous about the complex ECU system.
1.) I am still guessing that it is ok to run the boat with the sender disconnected?
2.) Does the sender ground wire actually go straight to ground? It disappears into a harness and I don't even know what color the wire is. Makes it hard to trace.
3.) Can I actually substitute my own ground wire to someplace convenient like the engine block and do no harm?
4.) Or should I just run a duplicate ground wire to a convenient place, leaving two grounds?

I'll stop here.
 
Regarding the engine questions, I would give Yanmar USA a call and talk to Michael Angland. He can give you the accurate numbers. This to me does sound like the sender is the problem or the ECU programming which both have service bulletins out to address them. I would start by removing the ECU and sending it back to Yanmar to have them flash it with the latest software. I would then start by checking the resistance in the grounding on the engine to the battery ground to ensure everything is ok.

If you need help getting in touch with Yanmar feel free to email me directly and I'll get you in touch.

Thank you,
 
If you look at the service bulletin you run a new ground wire from the sending unit to the paddle wheel ground wire. The upgraded software version I have is 1.13 and it is the teleflex smaller black box on the port side near the fuel filter that needs to be updated if the software is the issue.
 
Yup, I had a nice conversation this AM with Michael from Yanmar USA. I don't have any of the low pressure alarms or fluctuating pressure issues. Just high pressure readings (incorrectly I hope). I fabricated a new ground wire that bolted directly to the block and no difference when it was working alone or was working in parallel with the existing ground. My diagnosis is "a bad sender".

I do plan to take my boat in for a 1000 hour service next month and will get the interface update at that time. However, I'd still like to prove the bad sender theory. I think I'll be able to test it next week and then all I have to do is get a new sender. If I can find one locally.

Are they easy to find?
Or expensive?
 
My new friends at Hinkley Yachts loaned me an oil pressure meter this AM.
I plugged it in and fired up the Yanmar.
At cold idle it ran at 39psi... slowly dropping down as it warmed up.
Still cold, I ran it up to 1300rpm and read 59 psi.
Then 2000 rpm - 61 psi
Then 2500 rpm - 64 psi

As it warmed up (still only at 130 degrees) I got:
26 psi at idle and 59 psi at 2000 rpm.

Then I reconnected my sender.
It ran nicely up until an rpm where it hit ~60 psi then it immediately jumped to 134 psi.
Obviously a bad point in the sensor.
Michael Angland at Yanmar agreed with my conclusion.

Now all I have to do is find a new sensor.
Waiting for a call from the guys at Hinkley.
Stay tuned.
 
Given the number of false oil pressure readings that seem to occur with the 4BY2 I would (if I owned one) install a mechanical oil pressure gauge as the final word. A Tee placed at the outlet for the electronic pressure sender will accommodate both gauges and ease your mind.
And to the OP - I am not aware of any 4BY2 actually having had an oil pressure failure. It is always a false reading, both high and low, from the electronic sender.
 
I was thinking of installing a "T" in the line. Not sure there is enough clearance overhead?
I did notice an additional (horizontal) screw that appears to be a second tap into the oiling system.
That might be a possible solution?

I should have checked it when I had it out....
Anyone know the thread size at the pressure tap on the engine?
Looked like a straight thread with a crush washer.
 
When you make modifications to the engine you are giving Yanmar the excuse to void the warranty and not cover any recall service bulletins. I was recently told this by a Yanmar dealer when I inquired about installing a Racor fuel system.
 
Interesting point...
Just exactly is the Yanmar warranty period?
 
I think it is two years or 2000 hrs. on everything and then five years or 3,000 hrs. on major parts, Block, head crankshaft rods/
 
More on the original topic: On the internet I was only able to find oil pressure sensors that had a 1/8 MPT connection. Our Yanmar engine connection is (as I recall) 14 mm straight thread with a crush washer. For a total of about $30 I was able to get a sender (0-150 psi, 10 to 180 Ohms) and a thread adapter. I installed it today and it worked smooth as silk. Good readings up and down. Quite happy. Much better than paying $200 for a "real" sender.

EXCEPT: With the extra thread adapter the sensor is now too tall. I'm afraid the engine cover will short out the connections on top of the pressure sender. This gives me a couple choices. I could take a hole saw and drill a 2" hole in top of the engine cover to prevent any possible shorts. OR, I might be able to get a short radius 90 degree elbow and put the sensor on it's side off to port. It still might require a bit of a trim on the side flange of the engine cover. Not sure what to do.

Gotta think about it. Open to ideas.
 
Can you glue a thin durable plastic to the underside of the cover at the location of the sensor? I would still examine it periodically to see if there is any wear from vibration. I would hate to see modification to the side rib because it may weaken the strength of the cover when "accidentally stepping on it. Cutting a hole in the top may be better, but I would worry about the top of the sensor not being protected. Would cutting the hole give you just the clearance you need? Perhaps cutting the hole and then tack welding a piece of metal above the hole and then painting it to match. And when all is said and done, maybe bite the bullet and the OEM sensor solves the issue. Look at it this way. You saved bucks doing all the work yourself. Treat yourself to a sensor. Will the $200.00 change your lifestyle?
 
Will $200 change my lifestyle. No, I guess not.... after all, I now own a boat ! Ha.

But yes, I was thinking of maybe cutting a the 2 inch hole and then being a little worried about moisture dripping down from above, I could glue a larger circle of rubber/vinyl over the hole. It would provide protection from above and would not cause the sender to short out.

Or I could glue a tupperware lid to the top of the engine cover. I only need a bout 3/8 inch of relief for the added height.
 
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