Determining engine temp

[California]

Your readings match what I found on my YM240 and posted here.

Oil & Fuel - Low oil pressure? No, bad sender!

I sometimes see questions here about what should temperature and oil pressure gauges show, and what causes the oil light to flicker. Maybe this longwinded narrative will answer some of these questions. I have owned my YM240 several years now with no issues at all, after an initial month...

www.tractorbynet.com

As CalG said, a diesel is most efficient at the hottest it can run without damaging anything.

Seems to me Yanmar's ultra simple design concept for the 240's intended that light as nothing more than a boilover warning.

How simple are these? There's not even a thermostat. Regen? Didn't exist 50 years ago. Fuel gauge? Nope. The three warning lights and the tach cover the essentials. The operator manual even allows running without a battery. A simpler machine for simpler times.

Edit - added:

 

[careyo63]

It came up on here no long ago about the Temp. light. Last week was one of the quickest it's ever came on before. Low 80's So I didn't even bother to look at the overflow bottle. Turned the key switch off and cut 2+ acres more. Actually forgot to turn it back on and make sure the Battery had a full Chrg.. Sure enough when I went to shut it down and noticed it. Turned the key switch back on " NO Temp. Light On"

 

[CalG]

The Fordson E27n (gas) doesn't have a warning light. As a matter of fact it doesn't even have a thermostat. The radiator top and bottom tank are both cast iron. Suggested coolant from the operators hand book is "clean water". Drain if there is a danger of frost." ;-)

Dang thing seems to do OK with the cloth radiator blind pulled up in winter, down in summer. If the coolant boils, I add more ;-)

 

[etpm]

A question that may seem simple but I can't seem to find an answer. Yanmar 240D (2 cyl. diesel), at what temp is it considered over-heating, and more importantly, where do you take that temp? I only have the idiot lights. I ran the tractor for 30 minutes in about 95' for 20 minutes and felt that the engine was getting a little warm judging from the heat blowing back on my legs. Using an IR thermometer, I checked the temp while the engine was running. Had 185-190 at the block, 165 at the oil fill cap, 170-175 at the head, 120 at the upper rad. hose, 135 at the lower, and 130 at the rad. cap. Thats a lot differences in temp depending on where I take it and I didn't find anything specific on where the best place to check is. Now this was only after 30 minutes but I've had it get hotter (I think!) when the ambient is over 105. So best spot to check engine temp to ensure I don't blow a head gasket?

Using an IR thermometer can give false readings, and these readings depend not only on the material but on the surface finish. Check out this link: Emissivity and Its Effect on Infrared Thermometer Readings - ennoLogic
readings/
I actually ran into this problem today. I was heating some brass parts for a shrink fit and knew that the parts were hotter than the IR thermometer was showing. I then remembered about emissivity and used a contact thermometer instead. I even tried the dull surface on the parts but it was apparently too shiny to give an accurate reading. In any case the contact thermometer did show the proper temperature, which was much hotter than the temp I was shooting for and the parts went together very easily. I'm sure that when I machine the assemblies tomorrow the two part assemblies will behave as if one solid piece.
Though I didn't answer your question my answer may explain the wide differences in your temperature measurements. I suggest you take some contact temperature measurements at the same places where you took your IR measurements and compare them. This way you can use your IR thermometer and correct for the emissivity difference, so you will know what the actual temp is.
Eric

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[CalG]

Using an IR thermometer can give false readings, and these readings depend not only on the material but on the surface finish. Check out this link: Emissivity and Its Effect on Infrared Thermometer Readings - ennoLogic
readings/
I actually ran into this problem today. I was heating some brass parts for a shrink fit and knew that the parts were hotter than the IR thermometer was showing. I then remembered about emissivity and used a contact thermometer instead. I even tried the dull surface on the parts but it was apparently too shiny to give an accurate reading. In any case the contact thermometer did show the proper temperature, which was much hotter than the temp I was shooting for and the parts went together very easily. I'm sure that when I machine the assemblies tomorrow the two part assemblies will behave as if one solid piece.
Though I didn't answer your question my answer may explain the wide differences in your temperature measurements. I suggest you take some contact temperature measurements at the same places where you took your IR measurements and compare them. This way you can use your IR thermometer and correct for the emissivity difference, so you will know what the actual temp is.
Eric

​

Yup! Post #7 suggested this same thing. Nothing better than a second opinion!