L2501 temp question - first time diesel owner

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l2501HST
Jul 5, 2022
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Michigan
Hi guys,
I have loved my l2501 and used it a minimum of once a week since I got it in july, but I am noticing something now that the temps are getting below 30. Basically it’s heating up extremely slowly. It starts up great with a few seconds of the glow plugs, and seems to run fine, but I have to see the temp needle move to where it sat in the summer and fall over the last few weeks. It takes 10-20 to get above the c and it is barely above it. Last week I was doing some light blade/ripping work on driveway with box blade for 30 minutes the moved firewood for 15 minutes including some light loader work with rotted wood. i had it in low gear and around 2k rpm and by the time I was done it was the temp was barely above cold. Then today i was running it putting the back blade on for winter and probably had it idling for 25 minutes in low at 1750 and then running around for 5 minutes in medium at 2000, same thing the needle barely moved. As I said it runs great and I even opened the hood and felt near the radiator and hoses it was warm but not warm as i would think after running for that long. I googled around for a bit and found some stuff about the thermostat, some thing to do with the engine being detuned, or that it was normal for small diesels. with The conflicting stuff I found online, I’d figure I’d ask here and get a definitive answer. with my limited but growing knowledge of diesel, I am hoping it’s normal. Thanks!
 

Motion

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Kubota MX5100HST/FEL
Aug 17, 2020
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If you have a infrared het gun measure the engine temperature at the engine temperature sensor and see what the temperature is, if it's 180-200 degrees that's good, if it's below then you may have a faulty thermostat.
 
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85Hokie

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Hi guys,
I have loved my l2501 and used it a minimum of once a week since I got it in july, but I am noticing something now that the temps are getting below 30. Basically it’s heating up extremely slowly. It starts up great with a few seconds of the glow plugs, and seems to run fine, but I have to see the temp needle move to where it sat in the summer and fall over the last few weeks. It takes 10-20 to get above the c and it is barely above it. Last week I was doing some light blade/ripping work on driveway with box blade for 30 minutes the moved firewood for 15 minutes including some light loader work with rotted wood. i had it in low gear and around 2k rpm and by the time I was done it was the temp was barely above cold. Then today i was running it putting the back blade on for winter and probably had it idling for 25 minutes in low at 1750 and then running around for 5 minutes in medium at 2000, same thing the needle barely moved. As I said it runs great and I even opened the hood and felt near the radiator and hoses it was warm but not warm as i would think after running for that long. I googled around for a bit and found some stuff about the thermostat, some thing to do with the engine being detuned, or that it was normal for small diesels. with The conflicting stuff I found online, I’d figure I’d ask here and get a definitive answer. with my limited but growing knowledge of diesel, I am hoping it’s normal. Thanks!
Diesels are inherently "cool" natured - despite looking a lot like a "gas" engine - their heat distribution is somewhat different.

If you let a diesel idle in cold weather - it will never move the needle much.

One thing to remember, when an engine "sits" - moisture collects in the crankcase via condensation, when the engine start to warm and the oil comes to temperatures it will "burn" off this moisture and allow that moisture to evaporate.

One of the worse things you can do to any engine is NOT allow it to get "hot" - in your neck of the woods, it gets rather cold, look on the highway and pay attention to the front end of an 18 wheeler, they will BLOCK off the radiator front so cold air cannot cool the engine.

Many here have made or bought a "bra" that goes around the exterior of the hood to hold the heat in - this allows the engine to warm up quicker and stay hot longer. OR owners will place a piece of cardboard in front of the radiator to slow the heat transfer down.

Many feel that using a diesel at the lowest rpm is "good" for the machine, "babying" the engine is maybe the worst thing you can do to a diesel. They are built to run, they built to work and work hard.
Nothing wrong with allowing the fluids to run through the machine at idle - but after a bit of time, crank up the rpm a bit and work the machine.

Test the temps at the radiator with the before mentioned infrared thermometer - you really want the coolant at the top of the radiator to be 200+ F - cooler than that is not where the engineer designed it to be run.
 
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TheOldHokie

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windyridgefarm.us
Hi guys,
I have loved my l2501 and used it a minimum of once a week since I got it in july, but I am noticing something now that the temps are getting below 30. Basically it’s heating up extremely slowly. It starts up great with a few seconds of the glow plugs, and seems to run fine, but I have to see the temp needle move to where it sat in the summer and fall over the last few weeks. It takes 10-20 to get above the c and it is barely above it. Last week I was doing some light blade/ripping work on driveway with box blade for 30 minutes the moved firewood for 15 minutes including some light loader work with rotted wood. i had it in low gear and around 2k rpm and by the time I was done it was the temp was barely above cold. Then today i was running it putting the back blade on for winter and probably had it idling for 25 minutes in low at 1750 and then running around for 5 minutes in medium at 2000, same thing the needle barely moved. As I said it runs great and I even opened the hood and felt near the radiator and hoses it was warm but not warm as i would think after running for that long. I googled around for a bit and found some stuff about the thermostat, some thing to do with the engine being detuned, or that it was normal for small diesels. with The conflicting stuff I found online, I’d figure I’d ask here and get a definitive answer. with my limited but growing knowledge of diesel, I am hoping it’s normal. Thanks!
Not at all what I see on my L3901. Normal operating temperature on it is close to mid-scale on the gauge. It takes a little longer to get ther in cold weather but 10 minutes is probably typical. Your gauge should get close to the summer reading even in cold weather. My gut feeling is either the gauge is reading low or the thermostat in the tractor is malfunctioning. With a machine that new I would certainly be checking with the dealer service department.

Dan
 
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The Evil Twin

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L2501, LA526,
Jul 19, 2022
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My 2501 runs cooler in temps below 40. Coldest I've worked it so far was in the mid 30s. It definitely takes more "work' to keep the needle in the normal operating range. Light work like I have been doing (pushing brush, gathering wood) definitely makes the needle stay in the lower range.
Check your top radiator hose. It should be hot. A thermocouple is more accurate than an infrared but either will do.
I fashioned a peice of cardboard in front of the radiator to keep temps up after that day. I cover about 1/4 of the radiator on the left side. Once I figure out if it's too much or too little I will make it out of Coroplast so it holds up when wet.
 
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Rdrcr

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L2501 w/ S2T Turbo Kit = 35 PTO HP (Current), B2601 (Sold)
May 7, 2021
671
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I agree with 85Hokie, diesels inherently run cool and are slow to warm. Even my Turbo’d L2501 takes time to warm up and continues to run cool during operation in lower temperatures.

Personally, I start the tractor. Give it say 5 minutes, during which I’m moving the tractor around and operating the hydraulics and selecting and installing my implements. After I’m done, I throttle up and get to work.

Mike
 

The Evil Twin

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Jul 19, 2022
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Yep, they dont generate much heat when unloaded. There is a reason most commercial trucks run high idle when parked in cold climates. Part time job I was a wrecker driver back in school. If I didn't idle up the truck when sitting waiting for a crash the heater would stop working.
 
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ken erickson

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B7100 hst, 2650 front mount snowblower, L2501 hst qa loader
Nov 21, 2010
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I have run my L2501 hst in temps ranging from low 90's to high teens Fahrenheit , 6 foot brush cutter, bucket work, grapple work. My temp rises to about a 1/4 of the way into the "normal" range with little to no deviation.
 
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JerryMT

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Kubota M4500, NH TD95D,Ford 4610
Jun 17, 2017
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The Palouse - North Idaho
Hi guys,
I have loved my l2501 and used it a minimum of once a week since I got it in july, but I am noticing something now that the temps are getting below 30. Basically it’s heating up extremely slowly. It starts up great with a few seconds of the glow plugs, and seems to run fine, but I have to see the temp needle move to where it sat in the summer and fall over the last few weeks. It takes 10-20 to get above the c and it is barely above it. Last week I was doing some light blade/ripping work on driveway with box blade for 30 minutes the moved firewood for 15 minutes including some light loader work with rotted wood. i had it in low gear and around 2k rpm and by the time I was done it was the temp was barely above cold. Then today i was running it putting the back blade on for winter and probably had it idling for 25 minutes in low at 1750 and then running around for 5 minutes in medium at 2000, same thing the needle barely moved. As I said it runs great and I even opened the hood and felt near the radiator and hoses it was warm but not warm as i would think after running for that long. I googled around for a bit and found some stuff about the thermostat, some thing to do with the engine being detuned, or that it was normal for small diesels. with The conflicting stuff I found online, I’d figure I’d ask here and get a definitive answer. with my limited but growing knowledge of diesel, I am hoping it’s normal. Thanks!
Unlike a spark ignition engine, which run very little peak cylinder temperature variation, the diesel runs with large variations in peak temperature. The peak temperature will vary with load and ambient temperature. That's because the engine is controlled by fuel flow. SO doing light work (low load) in cold temperatures will take a while to warm up. The thermostat should control the coolant temperature to whatever the thermostat is rated to but in cold temperatures with light work it may barely be cracked open. As you apply more load and peak temperatures rise and are held, the thermostat will open to control the coolant temperature and the needle will rise but perhaps not to the same temperature you see on a cold day. So what you are seeing is perfectly normal.
 
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TheOldHokie

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Apr 6, 2021
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windyridgefarm.us
I have run my L2501 hst in temps ranging from low 90's to high teens Fahrenheit , 6 foot brush cutter, bucket work, grapple work. My temp rises to about a 1/4 of the way into the "normal" range with little to no deviation.
That is what I would expect and exactly what I get from my L3901.

Dan
 
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MountainMeadows

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L2501, JD 655, Ford 841, JD 6x4 Gator, Gravely 432.
Jun 6, 2022
222
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I have run my L2501 hst in temps ranging from low 90's to high teens Fahrenheit , 6 foot brush cutter, bucket work, grapple work. My temp rises to about a 1/4 of the way into the "normal" range with little to no deviation.
That's also where my 2501 runs on the temp gauge.
 
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BigG

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l2501, FEL, BB, Rotary cutter, rake,spreader, roller, etc. New Holland TL80 A
Sep 14, 2018
1,951
770
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West Central,FL
I would do as the other have suggested and cover part of the radiator. I do not think there is anything wrong with the gauge not moving but I like the idea of the engine oil being thinner with a little warmth to protect the engine better thus showing the gauge warm up a little.
 
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The Evil Twin

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L2501, LA526,
Jul 19, 2022
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Virginia
Tried out the Coloplast sheet today. It was 35°. Did some dirt moving filling in the old burn pit. Temp gauge stayed in the 1/4 range and no higher. Didn't go down when I headed back on the road about 1/3 mile. The nice thing I did notice when I put it away is that the lower coolant line was nice and warm. Not too hot to touch, just felt good on cold hands. Lol. Before blocking part of the radiator, the lower line was cool. Diesels love the warmth!
Probably wouldn't leave it blocked in >40°
 
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jimh406

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Kubota L2501 with R4 tires
Jan 29, 2021
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I was out in 25 degrees plowing. My L2501 acted exactly the same. I have no idea why some are lower than normal at low temperatures.
 
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DaveFromMi

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L3901 RCR1260
Apr 14, 2021
610
530
93
Indiana
I have dealt with diesel engines in trucks working in automotive HVAC and cooling. Without some intervention like lowering the airflow through the engine when cold, they take a long time to warm up. When under max loading, they require more cooling (rad/water pump) capacity than a similar sized gas engine. Intervention is necessary in this country due to federal requirements for defroster clearing.
Also a quick (subjective) check for the thermostat. The coolant bypass hose should heat up and no heat should be felt off of the back of the radiator fan until the thermostat opens. Bypass hose or pipe should be hot to touch before thermostat opens and hot air is noticed.
 
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07wingnut

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Feb 13, 2016
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When winter comes, I slip this in front of the rad. Works like a charm, without it, the gauge never gets
above the cold mark.

radscreen.jpg
 
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Trustable

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l2501HST
Jul 5, 2022
193
128
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Michigan
Hey all thanks for the replies I did some more work with it during my lunch for 30 mins yesterday and at night moving and back blading dirt to make trails. Definitely the hardest I’ve run it since it started getting cold. It did get hotter than last few times probably 1/4 to the center of gauge, I’ll include a pic. The radiator cap was cold to touch but the top hose was hot along with plastic at top of the radiator.
D7BDC733-CEE5-42AE-AF82-AC82E112A229.jpeg
 

fried1765

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Kubota L48 TLB, Ford 1920 FEL, Ford 8N, SCAG Liberty Z, Gravely Pro.
Nov 14, 2019
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Hey all thanks for the replies I did some more work with it during my lunch for 30 mins yesterday and at night moving and back blading dirt to make trails. Definitely the hardest I’ve run it since it started getting cold. It did get hotter than last few times probably 1/4 to the center of gauge, I’ll include a pic. The radiator cap was cold to touch but the top hose was hot along with plastic at top of the radiator. View attachment 91583
I think your tractor engine would like to run warmer than that!
 

The Evil Twin

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L2501, LA526,
Jul 19, 2022
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113
Virginia
Hey all thanks for the replies I did some more work with it during my lunch for 30 mins yesterday and at night moving and back blading dirt to make trails. Definitely the hardest I’ve run it since it started getting cold. It did get hotter than last few times probably 1/4 to the center of gauge, I’ll include a pic. The radiator cap was cold to touch but the top hose was hot along with plastic at top of the radiator. View attachment 91583
The rad fan runs with the engine speed so it'll cool the coolant off pretty quick. Lower hose was probably cold. But the top hose should always be hot. So your engine had some heat in it. That's good. It just takes more load to get the temps up when it's cold out.