Oil pressure readings ?

[Boo2]

Hi,

What oil pressure readings should I see from a Nanni N.38 ? This evening I started it up and the oil pressure went to 4 Bar but when I turned it off after half an hour or so, including a small turn around the harbour, the oil pressure reading had dropped to around 2 Bar. Is that normal and to be expected ?

There were no signs of anything amiss in the engine compartment after the run.

Boo2

 

[William_H]

Oil pressure on cars (i guess it is the same) is a function of engine speed but is regulated to a maximum by a pressure relief valve. However pressure will drop at low engine speed below the relief valve pressure. When the engine is warm it is normal for pressure at idle to be lower. when the engine bearings are really worn it is normal for the pressure to drop so low at idle that warning light comes on. My guess is that 2 bar is OK. A manual on the engine might indicate what it should be. good luck olewill

 

[VicS]

ITYWF that at operating revs the oil pressure should be 3.5 bar. .... but check with your manual
Provided that is achieved and the warning light/ alarm does not operate at idle speed you have no cause for concern.

 

[johnphilip]

Good thing about modern cars and boat engines is removal of oil pressure guages. Just something else to distract you and the chances of watching it or the temp guage just at a critical moment when something goes drastically wrong are small.

 

[Avocet]

No idea about that particular engine, but on most engines it completely normal for the pressure to drop when warm because the oil thins out. 2 Bar sounds (intuitively) fine to me. I guess the warning light will come on between 0.5 and 1 Bar, so that's still quite a margin.

 

[Lakesailor]

It's perfectly normal

"Oil pressure at maximum revs 2-4 bar"
"oil pressure at idle (850 rpm) 0.5 bar"

Manual http://www.nannidiesel.si/files/docs/Notice de conduite N4.38 ENG.pdf

 

[Boo2]

It's perfectly normal

"Oil pressure at maximum revs 2-4 bar"
"oil pressure at idle (850 rpm) 0.5 bar"

Manual http://www.nannidiesel.si/files/docs/Notice de conduite N4.38 ENG.pdf

Thanks Lakey, that would seem to be chapter and verse. As you say it's right in the range.

Boo2

 

[Lakesailor]

If you scan instruments regularly do what we do in cars an turn the gauge in the panel so that the needle will be vertical at the normal running value. Then a needle that is out of vertical will stand out.

 

[jakeroyd]

Reminds me of a few years ago motoring near Teignmouth in zero wind.
Westerly Centaur with the old MD1B.
Looked at the oil pressure gauge which read zero!
Stopped engine.
Then realised we , a) could not sail , b) could not anchor (way to deep) c) were drifting towards the cliffside.

So nothing for it to start the engine and wreck it motoring to Torquay.

The engine survived.
We later found it had a broken crank where the cup and cone from the break were still driving the whole thing round.

 

[Boo2]

If you scan instruments regularly do what we do in cars an turn the gauge in the panel so that the needle will be vertical at the normal running value. Then a needle that is out of vertical will stand out.

That's an idea, I wil check the panel and see if it's possible. Otherwise I could paint a mark I suppose.

Boo2

 

[ffiill]

Reminds me of a few years ago motoring near Teignmouth in zero wind.
Westerly Centaur with the old MD1B.
Looked at the oil pressure gauge which read zero!
Stopped engine.
Then realised we , a) could not sail , b) could not anchor (way to deep) c) were drifting towards the cliffside.

So nothing for it to start the engine and wreck it motoring to Torquay.

The engine survived.
We later found it had a broken crank where the cup and cone from the break were still driving the whole thing round.

Not a boat but that once happened to a Metro of mine-a new crank and it lasted another 6 years.