Determining engine temp

   / Determining engine temp #1  

jimjumper

Bronze Member
Joined
Oct 4, 2016
Messages
78
Location
Hemet, CA
Tractor
Yanmar 240D, 8N Ford
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?
 
   / Determining engine temp #2  
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?
When I was in TN and got the YM2610, the days above 95F ambient causes the TEMP light to come on and the engine lost a deal of power, so I quickly dropped the RPMs and let it work at cooling down. The light went out and the power was coming back. So, I just carefully drove it back home to park it. Ever since then, I never take it out when ambients are hovering in the upper 90s or higher.
 
   / Determining engine temp
  • Thread Starter
#3  
The service manual says the water temp sensor closes at 212 +/- 5' and since its in the top of the water pump I would assume if the light comes on that the head is 230+. Thats awfully hot from what I understand about the head and head gaskets.
 
   / Determining engine temp #4  
These engines were originally designed to run in the tropics, southern Japan and Southeast Asia. The temps that you measured look in the normal ranges to me, but IR temperature readings need emissivity calibrations for accuracy. Rubber, painted steel, and bare metal have quite different emissivities and differences in thermal gradients. It is hard to compare your measurements to absolute from a distance.

I tend to look at the exhaust manifold, the block, and the upper and lower radiator hoses to get a sense for whether the engine is getting a) overfueled, b) has a cooling problem, c) whether the radiator & pump are working, respectively. Not in the service manual, I agree, but it is a quick check. I would repeat your measurements after ten or fifteen of work minutes on a cool day, just to give you a sense of how much the outside air temperatures affect your machine, given your IR thermometer.

If you aren't losing power and your high temperature light is off, I wouldn't sweat it. I also wouldn't assume that the head is necessarily at 230F when the light goes on. If it does go on, I would throttle down, and let the engine cool down for ten or fifteen minutes before either resuming work or shutting it down.

All the best,

Peter
 
   / Determining engine temp #5  
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?
I would take readings at the housing where the upper radiator hose connects, that should five you a reasonable coolant temp reading. As ponytug mentioned those temps are not a concern at all.

 
   / Determining engine temp #6  
Best engine efficiency happens at the highest temperatures that the sealing elements can withstand. Hence boiling temperature suppression additives (anti-freeze) and pressurized radiator caps.

Unfortunately, Lubrication oils do not like temperatures much above 230 F.

So... I figure 225 ...I see it all the time on my motorcycle. AND DO NOT WORRY!
 
   / Determining engine temp #7  
These engines were originally designed to run in the tropics, southern Japan and Southeast Asia. The temps that you measured look in the normal ranges to me, but IR temperature readings need emissivity calibrations for accuracy. Rubber, painted steel, and bare metal have quite different emissivities and differences in thermal gradients. It is hard to compare your measurements to absolute from a distance.

I tend to look at the exhaust manifold, the block, and the upper and lower radiator hoses to get a sense for whether the engine is getting a) overfueled, b) has a cooling problem, c) whether the radiator & pump are working, respectively. Not in the service manual, I agree, but it is a quick check. I would repeat your measurements after ten or fifteen of work minutes on a cool day, just to give you a sense of how much the outside air temperatures affect your machine, given your IR thermometer.

If you aren't losing power and your high temperature light is off, I wouldn't sweat it. I also wouldn't assume that the head is necessarily at 230F when the light goes on. If it does go on, I would throttle down, and let the engine cool down for ten or fifteen minutes before either resuming work or shutting it down.

All the best,

Peter
Well PRESENTED!

Give that IR heat gun a through look around on a COLD engine, when you know the ambient temperature before you jump to conclusions about it's representation under elevated temperatures.

IR "heat guns" are just about the must fickle things ever created.
 
   / Determining engine temp #8  
You will hear between 180 F and 225 F however IMHO
190 F to 200 F is a good temp you want to keep a temp
that will help keep the engine to burn clean so you don't
have to regen so often

willy
 
   / Determining engine temp #9  
The 2000 and 226 both use the same sensor. The 226 manual states the red light comes on at 230F so according to Yanmar 230F at that location is to hot. Both tractor use a 13# radiator cap.
 
   / Determining engine temp #10  
My Temp lights been coming on from a bad circut for 16yrs.. I checked the heat temp. with a Thermal gun and Thermometer of the actual coolant when it started happening. I stay in the Low 190's even when the light decides to come on. I mow in 80-90+ Deg. temps. regularly. In Ga. summer temps get up there.
 
 
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