Low Oil Pressure Reading

[elad]

For as long as I have owned my 2000 28te, 10 yrs, the oil pressure reading has been low at low rpm. It reads just above the red zone and once warmed up will dip ever so slightly into the red. At r my above 1500 reading is well into the proper zone. I have checked with Mastry Marine and my local diesel mechanic who both say there should be no problems. So I have not concerned myself with the low readings. Still, it just does not seem right. Anyone else experiencing low oil pressure readings?

[Carl]

I assume this is a Yanmar? Mine is a 2006 and since new, pressure readings at anything below 1200 RPM look to be about 15-20lbs which I too consider to be low, but was told that is normal. At cruise it looks to be around 45lbs. No problems so far and just went over 1130 hrs.

[carolmarie]

As Carl mentioned, assume you have a Yanmar. Very common "complaint". I have a 2001 6LP-STE and it has ALWAYS read in the red at low RPM. Early on I had the sending unit replaced (over $100) and it didn't help, so I discussed the situation with Yanmar technitions at a Newport boat show (back in 2003). Short answer - no problem so long as you don't get an annunciator alarm. Seems that the gages that Yanmar used back then were from their industrial series and those engines run mostly at higher loads (I.e. RPM) so they don't hover near the red markings. Yanmar's solution to the many expressed concerns was - now don't laugh - they simply changed the red markings to blue! In fact, they sent me a new gage shortly after the boat show. It' still in my miscellaneous parts box. I never installed it.......
Don.

[rcwhite]

From the YANMAR service manual
When testing with a mechanical guage at the engine.
Oil Pressure at normal engine temp.
@ 800 RPM: 0.3 kgf/cm2, 0.03 MPa or more (4.26 psi)
@ 3800 RPM 4.5 kgf/cm2, 0.44 MPa (64 psi)

Given the wide range on the dash guage, the low side would barely register.
This was one of the first things I looked into on our 28 as it was
disturbing to look up at the guage even though it never read that low:)
I was planning on changing it to more closely match the operating range
of the engine at some point just to make myself feel better.

[elad]

Yes, my engine is a Yan Mar 6lp-ste. Glad to hear others have experienced the same low readings and that it appears not to be a problem. Sure do not like the red readings though.

[RobS]

Those circa 2000 Yanmar OEM gauge clusters, (type B, C, D) are terrible for a few reasons, the oil psi gauge is one of them. Here's the VDO gauges when I redid my dash giving a much clearer reading...

[Maye Marie]

I have had similar experience with low pressure. Mine always showed low and then started to drop very low while pushing hard underway. I had switched out the sender unit and installed a mechanical gauge to go with it. The mechanical gauge always reads much higher than the Yanmar gauge and shows expected pressure. The electrical gauge for some reason will let you know you have pressure but does not give a good accurate PSI reading.

If you would like piece of mind you could do what I did. From auto parts get a mechanical gauge. Install a tee were the sender threads into engine. Then put the sender on one side of tee and the mechanical line on the other side. I mounted my mechanical gauge right on the stringer next to the engine and will open engine box and take a look if I am concern or to get a comparison from both.

[socalmike]

Anyone have a pic of this type of set up. My oil pressure reads low as well but read perfect at the block. Thanks. Mike

[Maye Marie]

Sorry I do not have a pick. Go to your current oil sender on the right side of the engine just below the oil filter. Remove the sender and install a tee as a bushing fitting. Then install your sender back on your tee and an oil line for the gauge on the bottom of the tee. Locate the gauge were you like for you.