yanmar oil pressure

[howardbruce]

We are in the process of purchasing a 2012 Ranger Tugs R29 and we have observed that the oil pressure at idle (670 RPM)
is 9 psi. The engine is a Yanmar 6BY2 and to me this is an unacceptable idle oil pressure. I was wondering if anyone has had a similar experience with the Yanmar 6BY2 engine?

Thanks for any opinions.

 

[Bruce Moore]

Bumping post delayed in moderation queue.

 

[fishheadbarandgrill]

That seems a little low for idle. What was your engine temp with that pressure. I think I'm around 18 psi at idle with engine temps in the 190 range.

 

[knotflying]

The yanmar oil pressure readings can be erratic. There have been service bulletins related to this. There was a software update and a wiring recommendation. The fastest and practical thing to do would be to put an ohm meter on the sensor and there is a table that correlates what ohms you should get at specific RPM's. The software then interpolates this to pressure. You could have a bum sensor also. You could also temporarily install a mechanical gauge on by removing the sensor and see what the real pressure is. I would bet that it is fine. The wiring fix is pretty easy also. It requires running a wire form the paddle wheel ground to the sensor terminal. The third fix is a software update. This was at the expense of Yanmar, but I doubt that will make good on that now. My 4BY2 had a pressure of 12 at idle and that was after warm up. specs below:
0 PSI + 10 ohms +/- 5
29 PSI = 52 ohms+/- 4
58 psi = 88 ohms+/- 4
87 PSI = 124 ohms+/- 5

 

[howardbruce]

Thank you all for the reply. The engine temp was 190 when oil pressure was 9 psi at idle.
The resistance vs. pressure table will be helpful, thanks. I agree that Yanmar will probably not be providing support for this issue. Checking the oil pressure with a mechanical gauge is on the to-do list.

 

[knotflying]

I may still have the service bulletin. If you want it email me at mrizzo8743@aol.com and I will send it to you.

 

[jpdewitt]

Nine PSI seems low at idle and the 6BY has a history of oil pressure gremlins.

We also had oil pressure issues with my 2012 R29 with 6BY.

Drop me a PM and I will send my contact info.

John & Della
Ranger Tug 29
Sunny Tug

 

[fishheadbarandgrill]

I had erratic oil pressure readings several years ago. A mechanic removed the sensor and installed an analog gauge and confirmed good pressure. The fix was to install the wiring mod.

 

[bobmiller801]

What is the specific procedure for the wiring fix.

 

[mfreeman_1998]

I had a similar issue with a 4BY2 Yanmar. I put a "T" where the oil pressure sender was located. One leg of the "T" went to an old fashion Oil Pressure Gauge and the other leg went to a new oil pressure sender. In this way, if I get a reading that is out of range I can check the old school Oil Pressure Gauge. Since making this update, I have not had any out of range events. For "peace of mind" it is great to have the second source for Oil Pressure Info.

 

[glider4]

+1 to knotflying!
The most likely case is that the oil pressure in your engine is just fine. As long as it shows full on the dipstick you are most likely fine. The problems almost always are in the software, the ground lead coming from the sensor or the sensor itself.
I’d start with the grounding. If bad it’s a fairly easy fix and the least expensive. A new sensor will run a couple of hundred bucks. I have no idea the cost of the software fix or if it’s still available from a Yanmar dealer.
After replacing the sensor with no improvement in problems our oil pressure issue was with the ground wiring. Fixed in under an hour by a knowledgeable Yanmar tech.
PS: If you’ve checked the dipstick and the engines full of oil try this. Run it for a minute or two and turn it off. Remove the oil fill cap and look to see that there’s plenty of oil all over the top of the engine parts. If so, that pretty much confirms that the problem is in the sensor system, not a problem with the engine.
PPS: Per page 72 of the 4BY2/6BY2 operations manual, normal oil pressure at 1,000 rpm is between 8.7 and 14.5 psi. At 4,000 rpm normal pressure is 51 to 87 psi.
https://www.yanmar.fi/content/download/ ... 6/file/by2