Two dip sticks

I

Irish Mist

Well-known member
Joined
Apr 25, 2012
Messages
1,175
Fluid Motion Model
C-288 C
Hull Identification Number
FMLT2922K011
Need help
I just changed oil and am having a problem I cruised out to a mooring spot and when I slowed to anchor I got low oil pressure warning I checked the long dip stick on the port side of the engine and it appears to be right in the sweet spot between the two lines The other shorter dip stick on the starboard side shows it above the the top line . Also I put in 5w 30 after looking at the chart I see before they had used 5w 40 all was good before I changed the oil. I pumped it out through the dipstick on the port side and put 10 liters back in to get to the levels I have . Oil is still clean not black this has me worried as I would think after an hour running it would be dirty. Temp is good just under 200
Thanks for any help
 
Mike, on Illusions, had a similar problem when the wrong oil weight was used.....he also got a low oil pressure warning even thou he had the proper oil level. He changed the oil and the warning went away. Subsequent to that however the warning came back on when he had another problem so I'd suggest you search the forum for his outcome and or maybe he'll chime in. Mike has the Yanmar 180, but I still think oil weight is a sensitive issue with our engines.

Jim
 
Did you run the engine for a bit right after you changed the oil? If the oil is too cool it may have never gotten up to the oil filter. See if you have oil in the filter. If not, pour some in there and then start it up. That should solve your problem. If that does not fix it, if you increase RPM a bit, does the pressure go up and the alarm stop? You could have a bad connection from the sensor wire to the harness, this happened to me. Oil pressure was fine but I was getting a false low reading. You could also have a bum sensor. This can be checked with an ohm meter. You have to remove the vanity plates and the sensor is at the top front on starboard. There are specific readings at certain RPM's. If it checks out at the sensor than it could be the connection at the harness.
 
Jim,
It turned out not to be the oil viscosity as an issue and Yanmar reimbursed me for the erroneous oil change.
 
Thanks for heads up on the oil weight, I was hoping you'd share what happened in your situation...it's good to have a refresher from someone who has had a problem resolved and that's what so great abut this forum.

Jim
 
Thanks guys
I came back to port and started out with 50 lbs pressure and watched it drop as temp rose It stayed around 20 droping to 6 as I slowed to dock... But no alarm. I really feel is an oil issue I Am going to pump it out got new filter and Oil from the Ranger dealer here that they have been using. Will report later with the outcome
Thanks
 
Grandpa, as one who watched much of Mike's conundrum with the 'low'oil pressure it turned out to be a combination of bad pressure sensor (partially) and a bad electrical connection in the harness (mostly)...
The oil viscosity was not the issue in the end and the engine never actually had low pressure, even at a hot idle... Remember that 6# at a hot idle you see on the electrical gauge may actually be 12-20 pounds if measured with a mechanical gauge...
I am not arguing against your oil change but I will be surprised if it changes anything in the end...
At 180-200 degrees the viscosity of straight 40 weight, 15W40, and 5w30, is similar, if not the same ... The advantage of the synthetic 5W30 or even a 0W30 is much less viscosity when cranking a cold engine - low viscosity equals less drag and a higher cranking speed... For those of us outside of Alaska/NWT that is rarely a problem...

Keep in mind that the second number of an oil's viscosity grade (30 in this case) is the steady weight of the oil when at 100 degrees C (212 degrees F) and it compares with any other 30 weight grade oil, in thickness, regardless whether it's a 0W-30, 5W-30 or 10W-30. The lower number oil is 'thinner' i.e. lower viscosity, only when it is colder not when it is hotter...

The difference in oil pressure at idle (hot) between a 30 weight and a 40 weight will be miniscule... Cold there will be a larger differential between the two weights... Let us know how it goes,,,

cheers - denny
 
You have exactly the same symptoms I had and it was the bad connection at the wire harness. You can change your oil and it'll be good for a while but the problem will crop up again it is not an oil viscosity issue it is something else. My oil pressure was showing only 24 pounds at high rpm around 3200. When I would start the engine with the oil cold the pressure would be higher and as it warmed up it would drop. It took the mechanic and Yanmar four days to figure out what the problem actually was so you might have to benefit of my experience.
 
Well wanted to update I drained oil and put in 15w40 ( what the dealer uses ) and all good again Just cruised for 3 hr all different speeds and pressure was as before from idle to WOT all good So I think was a combo of viscoicty and the first oil did not say for diesel
Thanks for all your replys is very comforting to know there is help waiting in the wings
Just at Swift Rapids in Ontario a great lock as only boat access so can relax knowing no tours tonight 🙂
Cheers to all !!
 
Grandpa Mark, keep an eye on this as Mike's alarm resurfaced after a few days running. If it does resurface you should revisit what Mike on Ilusions had done, as spelled out in his post.

Jim
 
Denny,
You have it exactly right about the oil viscosity with multi-grade oils. The viscosity does not increase at temp but remains at a more constant level.
Bob
 
Well, hopefully your problem is resolved, but time will tell. I was good for about one week and then it raised its ugly head again. The good news is that it is not a catostrophic occurrance if it does happen.
 
Thanks for the heads up I am keeping an eye on everything at this point I really feel though it was totally the wrong oil for this engine and was just breaking down. But I agree the viscosity shouldn't make that much differance
 
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