Farymann K34 - low oil pressure warning

[bouton]

I have a single-cylinder, raw water cooled diesel engine Farymann K34 of 6HP. After half an hour at a load and at 2500 rpm, a low pressure oil lamp flashes. After an additional half an hour, a low pressure oil lamp was constantly on. If I wait a little bit to cool down and dirve with 1500 rpm sometimes I don’t get lamp on.
The cylinder temperature measured with the IR gun is about 60-70 degrees Celsius, and the oil tank - bottom part of the engine around 70-80 degrees Celsius.
Is this a problem with weak engine cooling or is it a problem with an oil pump or something else?
Do someone have any experience with this kind of failure?

Thanks for the advice!

[Compass790]

Can't believe you didn't get any replies, obviously not nearly as sexy as hydrolockeds' problem altho the result could end up worse. Thought it would help having yr own thread but my guess isn't panning out too well.
Check on the engine & propulsion forum for Farymann help offered. pwillets may be your best bet, try PM to him. If he has a workshop manual maybe he will share. Lotta posts on descaling if you search. Let us know if that & oil pump tolerances check helps.
Don't let the problem lie. It needs to be fixed asap

[a64pilot]

Your first step in my opinion is to verify oil pressure.
Easiest and cheapest way to do that is with an inexpensive direct reading gauge temporarily installed, usually you can unscrew the oil pressure sending unit and connect the gauge.

Then you will know if you have an actual pressure problem, or hopefully just an indicator going out.

Your oil temp does sound a little high, but not much, and may be normal. I’m not familiar with that engine.
But normal average automobiles often run about 100c oil temp.
I’d expect a small, I assume raw water cooled engine? To run cooler though.

[NCboatrx]

The K34 has an oil strainer that must be cleaned out.
This is likely to be the problem.

[Compass790]

Originally Posted by NCboatrx

The K34 has an oil strainer that must be cleaned out.
This is likely to be the problem.

Oh yeah, that would be my first step. Not knowing he had a strainer I said to OP to try descaling & check his oil pump as his temps seemed too high for a raw water cooled engine.
Must look at my ladyfriends Farymann to see if it has a strainer. I think it's a 10hp though. Thanks for the post.
Please let us know if you have done the strainer previously or what happens when you do Bouton.

[NCboatrx]

@Compass790. If the engine is your ladyfriend's boat is an A30, that engine has no oil pump as it is all splash lubricated.

[bouton]

Can dirty oil stainer has an impact in low pressure, when engine becomes hot? I assume if oil has less viscosity in higher temperatures, oil stainer should make less problems? Or I am wrong?
And K34 - engine I have has an simple oil pump with diaphragm for releasing too much pressure. And an oil stainer too. Engine A30 does not has an oil pump. And it is a different engine.

[a64pilot]

Originally Posted by bouton

Can dirty oil stainer has an impact in low pressure, when engine becomes hot? I assume if oil has less viscosity in higher temperatures, oil stainer should make less problems? Or I am wrong?
And K34 - engine I have has an simple oil pump with diaphragm for releasing too much pressure. And an oil stainer too. Engine A30 does not has an oil pump. And it is a different engine.

It’s a battle of which is worse, restriction of thick oil or how easily the thick oil is released by loose tolerances, so yes it could

Either way of course the screen is easily checked and cleaned, and that possibility eliminated. If the screen has been serviced like it should, it’s not clogged, all that should ever get in the screen is carbon from the underside of the piston, air cooled VW’s had such a screen and the Kubota in my generator does.

If the oil pressure loss was sudden, then I’d suspect a stuck cold oil bypass valve or similar. If it has slowly decreased over the years, well that sounds like wear.
If it was due to wear, I’d run 50W oil to get the pressure back myself, but don’t until you confirm it’s a worn engine causing low oil pressure.
Start thinking about an overhaul or repower, maybe not right now, but eventually.
It may run for years longer or may spin a bearing tomorrow, but that pretty much true for any engine.

[Compass790]

Agree with A64,
It's easy to clean a strainer & should be done first. Our engine pickup tube filter gauze was partially clogged with some gummy substance after I pulled the engine apart when it was 34 years old. I say this just to show what can happen. I cleaned it off with brake cleaner. Sump had about 10mm of sludge on the bottom too
It's easier to do your descale for a start, then if that doesn't work, move onto oil strainer ( do that any way as it's a maintenance item as per manual) then oil pump then bearings.
I dont know where you are but in Australia & NZ you can get 20w-60 diesel oil that may help after you have descaled & cleaned the strainer if you wish to delay doing oil pump & bearings