Oil Filter may have killed my engine

[Compass790]

Originally Posted by Olly75

The sender and gauge are both made by stewart warner, and it turns out have to be matched correctly. So went back to the shop and they swapped the sender for the right model and now everything is working fine.

My wallet is just lighter from the time the mechanic had to spend trying to work out what was going on.....

Yes but I feel for the mechanic as not an easy problem to diagnose without the benefit of hindsight except if it was running on 3 cylinders from startup. Good lesson in your story, check oil pressure gauge if changing it.

[hpeer]

Since we are on the topic.... what is a typical minimum oil pressure you should see?

At 800rpm my Yanmar is about 20psi, it goes up to about 58psi at 2,000 rpm.

Somewhere I read that anything over 12 psi will get the job done but is indicating an impending problem.

[a64pilot]

Originally Posted by hpeer

Since we are on the topic.... what is a typical minimum oil pressure you should see?

At 800rpm my Yanmar is about 20psi, it goes up to about 58psi at 2,000 rpm.

Somewhere I read that anything over 12 psi will get the job done but is indicating an impending problem.

It’s engine specific, some very old engine designs ran very little oil pressure, more modern ones much higher, especially turbo motors.
Then what has become the rage for very high performance engines is controlling oil flow to provide only what is necessary, cause there is a surprising amount of HP lost in excess oil drag, so those pressures have come back down again.

Then you have hot oil pressure and cold oil pressure. Engine on my little airplane runs about 40 or maybe 50 cold oil pressure, but it will drop to about 30 or so when oil temp gets up to about 200f.
Used to worry me, then I got my float plane ticket on Cubs (same engine) and they were running only 20 or so.
These are at cruise RPM, idle maybe 10 or less?

My Yanmar 4JHE pretty much duplicates your oil pressure if we are talking hot, if cold, my idle is much higher, but the high side is about 60, cause I think that is relief valve setting in the oil pump.

Finally make sure you verify the accuracy of the gauge before you take any action if any.

[a64pilot]

The low oil pressure switch for a 4JHE is set to .5 kg percc2.
Pretty sure that is 7.1 PSI, so it seems 7 PSI is the low oil pressure danger point?

[Compass790]

What A64 pilot says, can only add that it seems that 10psi per 1000 rpm seems to be a minimum on google searches. Yours sounds good. Some low pressure/high flow diesels run as low as 8psi according to Peter Compton from sailboat maintenance manual. Our Yammer spec is 35-50lb ( YSM8 ) but doesnt specify at what revs or what temp.

[Wotname]

Originally Posted by a64pilot

The low oil pressure switch for a 4JHE is set to .5 kg percc2.
Pretty sure that is 7.1 PSI, so it seems 7 PSI is the low oil pressure danger point?

Yes, Yanmar appears to use oil pressure alarm switches of around 7 to 12 PSI in the couple of manuals I have read except for their older engines (Y and Q series) where it is apparently much lower.

The YSE manual states 0.5 PSI but that seem wrong to me - maybe a translation error or typo - perhaps it was meant to 5 PSI. I have got a couple of these switches and I must measure them one day...

[Dymaxion]

The YSE manual states 0.5 PSI but that seem wrong to me - maybe a translation error or typo -
--------
Probably a typo for "0.5 Bar" meaning as mentioned before around 7.1 psi. I'm used to VDO sensors and gauges from European cars. All measure in "bars" equivalent to 14.6psi (that being one atmosphere)

[Olly75]

Originally Posted by Compass790

Yes but I feel for the mechanic as not an easy problem to diagnose without the benefit of hindsight except if it was running on 3 cylinders from startup. Good lesson in your story, check oil pressure gauge if changing it.

Yep proper PIA to diagnose! Will now always check serial numbers when I replace electronics that work in tandem.

Talking of replacing..... it appears I was preemptive when I said I had dodged a bullet after the siezure. I have to pull and rebuild engine. Nightmare.

[hpeer]

Don’t leave us hanging like that. What happened?

[Olly75]

Well, got her running at the dock for an hour no problems at all, up to temp and oil pressure responding as the revs increased, so next day took her out for a proper run in a decent wind and waves. Intention was to run her at 2500 for a couple of hours and then increase to 3000 for 15 minutes to burn out any crud.

All was going well had her at 2000 rpm and there was some smoke in the engine room but couldn't identify where it was coming from, at 2500 smoke got really bad and oil pressure started to drop off, so stopped, turned round sailed back and called Boat US for a tow into the slip (IM not on first name terms with the skippers, but we are getting to know each other.....)

Let her cool off over night and then started her up. Revved up to 1500, she started blowing smoke/gas out of the oil filler, sounds rough and you can hear a tapping sound over the engine noise, took the cap off and and smoke was really bad.

So hard to say what is actually wrong but not good and needs a rebuild. This is where the trouble really begins, basically I have to remove the helm, cockpit floor, generator, all the fuel system and quite alot of the wiring to be able to lift the engine out.

Oh, and my visa runs out on the 27th May, so need to try and persuade the powers that be to let me back in the country.

Fun times.