Oil Temperature - Small RWC Engine???

[Wotname]

Does anyone know what the normal operating oil temperature is for Yanmar GM or Y series raw water cooled engine?

I am asking as I am building a custom oil temperature gauge for a YSE 8 and I need a normal oil temperature number to fix the mid scale section of the gauge.

So far a quick CF and google search has lead to no definitive answers.

FWIW, engine water temperature for these engines is around 45C to 50C so I'm guessing oil temperature is maybe 60C but I'd rather know than just guess

[shakey doug]

Oil temps 45c to 70c Max. Never above 85c as oil starts to oxidise causing sludge ete.

[Dockhead]

Originally Posted by shakey doug

Oil temps 45c to 70c Max. Never above 85c as oil starts to oxidise causing sludge ete.

Oil oxidizes at 85C? I had 2.2 liter Porsche 911Ss which were basically oil cooled, which ran IIRC, at 110C. And lasted forever.

[jimbunyard]

"For most mineral oils, a general rule of thumb is that the rate of oxidation doubles for every 10°C (18°F) rise in temperature above 75°C (165°F). Because of this, synthetic oils are often required in high temperature applications to prevent rapid oil oxidation."

The Lowdown on Oil Breakdown

So 60c seems a good safe guesstimate to me...

[shakey doug]

As this is a Marine Diesel forum I was referring to diesel detergent class oils.

[Dockhead]

Originally Posted by jimbunyard

"For most mineral oils, a general rule of thumb is that the rate of oxidation doubles for every 10°C (18°F) rise in temperature above 75°C (165°F). Because of this, synthetic oils are often required in high temperature applications to prevent rapid oil oxidation."

The Lowdown on Oil Breakdown

So 60c seems a good safe guesstimate to me...

I don't know any car that runs oil temperatures as low as 75C. The usual oil temperature in a car as far as I understand is 90C to 100C, with 90C to 95C being typical coolant temperature (thermostat opening temperature).

The oil in my Yanmar is sea water cooled, and in my cold waters the oil seems to run about 65C most of the time (operating temp of the engine is 80C). I worry that 65C is too cool to boil off condensed water.

I guess we would need a real lubricant engineer (paging Vyv Cox) to give us the real answer; certainly what I am writing is amateur speculation and probably not worth much. But for whatever little it may be worth: I don't think that oil oxidation or wearing out of the oil molecules is at all the life-limiting factors for our main engine lube oil. That would surely be the accumulation of soot and acid, which is what determines our oil change intervals.

[a64pilot]

Modern automobiles oil temps do run about 200f or a little higher. Oil temps seem to follow water temp pretty closely, just a little higher.
With aircraft piston engines, oil temps above 180f are sought to cook off moisture, below 180f and your block off some airflow to the cooler to raise the temp.
However as has been pointed out, we aren’t talking about cars or airplanes here. Oil temps for our little Diesels run much lower, so much lower, it has me wondering why my 4JHE even has an oil cooler.
You can get a real good idea what your oil temp is by pointing a IR thermometer at your oil filter when you have been cruising for an hour or so, if memory serves, mine is about 160F or so, about the same as the water temp.

As with most Diesels that are not heavily stressed, oil is changed to remove the soot mostly, until very recently Diesel oils had very high TBN and could therefore neutralize quite a lot of acid, but many modern Diesels run converters, and the metals that constitute TBN poison converters, and modern fuel is ultra low sulphur, so maybe modern Diesel oils have lower TBN?

Check your oil temp with an IR thermometer and if you don’t mind, post the results. I’m betting it’s lower than most of us realize.
Turbos are a different animal of course, the Center section of a turbo is usually oil cooled, and therefore a turbo can dump quite a lot of heat into oil.

This is aircraft only, but may shed some light on oil temps
https://generalaviationnews.com/2004...l-temperature/

[Dockhead]

Originally Posted by a64pilot

. . . .
Turbos are a different animal of course, the Center section of a turbo is usually oil cooled, and therefore a turbo can dump quite a lot of heat into oil.. .

Just a random remark -- my Yanmar's turbo is water cooled, and I think most modern marine diesels with turbos are the same. It must have quite a lot of water flowing through it, because the turbo stays at coolant temperature.

Like you, I measure these temps with an infrared thermometer. Oil temperature from the oil filter.

[jimbunyard]

Originally Posted by Dockhead

I don't know any car that runs oil temperatures as low as 75C. The usual oil temperature in a car as far as I understand is 90C to 100C, with 90C to 95C being typical coolant temperature (thermostat opening temperature).

The oil in my Yanmar is sea water cooled, and in my cold waters the oil seems to run about 65C most of the time (operating temp of the engine is 80C). I worry that 65C is too cool to boil off condensed water.

I guess we would need a real lubricant engineer (paging Vyv Cox) to give us the real answer; certainly what I am writing is amateur speculation and probably not worth much. But for whatever little it may be worth: I don't think that oil oxidation or wearing out of the oil molecules is at all the life-limiting factors for our main engine lube oil. That would surely be the accumulation of soot and acid, which is what determines our oil change intervals.

My response was just to Wot's request if 60C seemed about right, which to me it did, given that his operating coolant temperature is in about the 45-50C (!) range.

The quoted paragraph comes directly from Noria, Analytical Services and Laboratory Studies | Noria Corporation which is an oil analysis firm. From a brief perusal of the company literature, I kinda think they might know what they're talking about, but I've been wrong before...

As for an analysis of the 'hierarchy of failure modes', I'd suppose that there may be one, though I'd suspect it's more contingent on service (load not maintenance) parameters as the ultimate factor, and that someone like Noria would be the one to provide the data...

[DougR]

My BMW 328i ran oil temps of 220f (105c) routinely, and that was right in the center range of the oil temp gauge.

DougR

[a64pilot]

A lot of more modern turbos are water cooled. My Chevy Duramax truck was my first water cooled turbo.
The primary reason for this is ignorant operators, if you run a turbo motor hard and then turn it off without allowing significant time to Cool, the center section is still so hot that it cooks the oil into coke. Coke of course destroys the center section bearing, the shaft will wobble and when the turbine contacts the housing, you get to buy a new turbo.
Water cooling prevents that, you can pull off the freeway directly into the gas station and turn the motor off without harm, the water keeps the center section Cool.
Plus more modern Diesels are designed to run with a turbo and “live” on boost, older motors were really just regular Diesels with turbos bolted on and may not see any real boost unless run hard.

There has been a lot of design changes with newer turbo motors, compression ratios, combustion chamber design and much broader RPM ranges with common rail, common rail is a real game changer.
In particular the blown common rail Diesel is not your Grandfathers Diesel, it is a completely different animal.
Even newer turbos with variable inlet guide vanes are a different animal, being much more flexible than their older siblings, a VVT turbo can give much more boost at lower RPM and yet not overboost at higher RPM like a regular turbo does.

My estimation is that a new generation common rail Diesel is a completely different animal, and will require a different care and feeding than an old fashioned low power, low RPM Diesel.

[mud bug]

Personally I wouldn't concern myself with oil temperature on a diesel boat engine. Coolant temp and oil pressure yes. Oil temp and coolant temp are coupled together. Odds of high oil temp without high coolant temp are slim to none as long one maintains correct oil level. That said, sound pre operation checks will eliminate the issue.

[Wotname]

Originally Posted by a64pilot

...............
Check your oil temp with an IR thermometer and if you don’t mind, post the results. I’m betting it’s lower than most of us realize.
........

Of course, why didn't I think of this - I have a fully operational RWC 2GM20 and a IR thermometer. I can answer my own question

Will advise in due course. I'm sure the YSE 8 temps will be ver similar.

[Wotname]

Originally Posted by mud bug

Personally I wouldn't concern myself with oil temperature on a diesel boat engine. Coolant temp and oil pressure yes. Oil temp and coolant temp are coupled together. Odds of high oil temp without high coolant temp are slim to none as long one maintains correct oil level. That said, sound pre operation checks will eliminate the issue.

I agree however in this instance the YSE 8 only had a oil pressure alarm so when I decided to add an over heat water temperature alarm along with a custom water temperature gauge, it was only a small step to add an oil temperature gauge. The water temperature gauge had to be custom as I could not find any suitable gauge that a mid scale point of 45 - 50 C.

The advantages are minor - some redundancy in measuring engine temperature and the fact that oil takes longer to reach operating temperature than the water. From flying, I recall learning never to apply full (take off) power before oil temperature has stabilised. Some old habits die hard!

Besides, when a making fully custom panel, any and every thing is considered . There will also be an oil pressure gauge, an expanded range voltmeter, a centre zero amp meter, a tach, an exhaust pipe temperature (with it's own alarm) plus off course idiot lights and buzzer. Way overkill I know for a single cylinder 8 hp diesel but why not...
FWIW, this is going into a small launch, not a sailing boat so the diesel engine is the primary power source.

[Elie]

The reason for not running hoter than 140-160 f a raw water cooled engine has to do with the creation of scale in the internal cooling passages of the engine. This scale is very hard, and a terrible heat isolant and may block the water passages. My fresh water cooled engine runs at 1282 de f without any problems of any kind, and certainly not with the lubricating oil.