Chronic Kioti DK40 SE Overheating - Seeking Advice on Removing Thermostat

[Williy]

Have you tried using a flashlight in the dark to see if the radiator is
clean all the way to the bottom?? Also check your hoses as they get
older they can collapse and cause a restriction. Also if your coolant
is not mixed correctly your radiator can over heat. If you add water
only use distilled water. IMHO a 50/50 mix is the best

willy

 

[Alan46]

A few days ago, ambient temperature about 80F, I wanted to see if the coolant was circulating since a poster said to check that. So I started the engine and slowly drove out of my garage in hydro low gear and 1300 RPM. Engine had been running only 3-4 minutes when I opened the radiator cap. Coolant splashed out - like it was overfilled. I was surprised - I thought I'd just see the coolant below the cap stationary (not under pressure like it was), and then as the engine warmed up and the thermostat opened begin to flow. The overflow bottle I've kept at about half - there is a fill line and its always been close to that when cold. It does go up and down.

I blew out the radiator with compressed air - higher PSI than 40. Probably 100 psi and then as I held the hand air valve open it dropped to 50-80 psi. Lots of fine particle dust, brownish, like before when I've done this. I blew it out front to back at first, then back to front - a long time moving all around the obstacles to get it to where no appreciable dust blew out. There is an oil cooler radiator low in front of the engine coolant radiator and that seemed to have a lot of dust. As an observation my tractor's engine coolant radiator has a lot of stuff in front of it. The battery, the oil cooler, the air filter housing, and a big air pipe from the air filter up and over the radiator top to the engine.

I can move the fan by hand about 1/8th revolution, but it takes almost all my strength. Is that too loose? Every time I've looked at the running engine at idle RPM that fan is spinning. I haven't looked at it with engine RPM at 2,500 RPM - I'd need someone at the controls before I'd do that. I moved it so I could blow out the radiator back to front where the fan blades had blocked the radiator. That allowed more dust to blow out, which was good to see. I don't think the drive belt is too loose, but possibly that is an underlying problem.

I then worked the tractor by bush hogging medium high stuff on fairly level land in two wheel drive, then engaged four wheel drive and went up and down the hillside bush hogging. Temp gauge stayed put.

I used the thermal sensing gun with the engine warmed up and stable and the gauge reading normal. All temps read plus or minus about 2 degree C as I moved the gun around. Temperature was 67C at the radiator cap, 67 degrees at the very front of the engine, and about 90C near the back of the engine. It was 67C at the rear differential area too. I'll carry the gun with me and if it starts heating up I'll check these areas again. Any tips here?

Thanks!

Finface

So does it run any cooler?

 

[Rhino35]

Have you tried using a flashlight in the dark to see if the radiator is
clean all the way to the bottom?? Also check your hoses as they get
older they can collapse and cause a restriction. Also if your coolant
is not mixed correctly your radiator can over heat. If you add water
only use distilled water. IMHO a 50/50 mix is the best

willy

I haven't tried the flashlight, but I will after flushing it. I'm going out today to blow it out again and then flush the radiator with the AC cleaner (spray can) I bought. I'll rinse the living shiitake mushroom out of both the engine radiator and the oil cooler. My hoses should be okay - they look new and are flexible and the tractor is stored indoors and has only 470 hours.

After I flushed the radiator coolant in September, 2022, before doing my fall annual tall weeds/small saplings hillside bushhogging, and in hopes I'd cure this vexing gradual overheating issue I did the below - copied from my maintenance notes for my 2013 DK40SE tractor;

"September 13, 2022 - flushed radiator, installed new thermostat. New mix of fresh Kioti coolant is an additional prevent overheating experiment. Assuming faulty thermometer, but also adjusting for more water (which cools better than glycol) and adding Water Wetter product for the first time. Water Wetter from AutoZone has anti-corrosion chemicals like Kioti brand antifreeze. Final coolant mix is 4% Water Wetter, 32% propylene glycol, and 64% distilled water - essentially a 32% glycol, 68% water mix. From an online chart I found that a mixture of 30% propylene glycol to 70% water has a freeze point of 8°F, with a burst point of -18°F. The freeze point of a 32% propylene glycol and 68% water mixture is approximately 5.6°F. Kentucky winters not usually that cold, plus my garage is kept heated in winter to 40F for any engine starts should I need to work the tractor."

 

[Rhino35]

So does it run any cooler?

Hi Alan,

It did for about a 45 minute workout, but it wasn't the tall stuff and the hills. Definitely blowing out the radiator and oil cooler helped because doing about the same work in May lead to overheating.

But the margin between not overheating and overheating is pretty darn slim if all it takes is that fine dust accumulating after about an hour of work, which I blew out. I can only carry a leaf blower with me and that hasn't gotten that fine dust out enough. So I have to really get those radiator fins flushed out.

Best,

Finface

 

[Alan46]

Hi Alan,

It did for about a 45 minute workout, but it wasn't the tall stuff and the hills. Definitely blowing out the radiator and oil cooler helped because doing about the same work in May lead to overheating.

But the margin between not overheating and overheating is pretty darn slim if all it takes is that fine dust accumulating after about an hour of work, which I blew out. I can only carry a leaf blower with me and that hasn't gotten that fine dust out enough. So I have to really get those radiator fins flushed out.

Best,

Finface

Sounds like you’re on the right track bro!

 

[Rhino35]

Sounds like you’re on the right track bro!

I hope so. Yesterday I blew it all out again with compressed air - and after only doing 45 minutes of work a few days ago was surprised how much of that brown dust was still in there. Then I sprayed that Nu-Calgon Evap Foam - used the whole large spray can - let it fulminate (it goes on white foam, then sorta liquifies and runs clear) for 20 minutes, and then rinsed it all out.

I also did my best to tighten the fan belt. With great effort I could turn the fan a bit without the belt moving, but it also was tight enough to turn the belt too. I did find a loose bolt at the lower engine side of the alternator, but that wasn't the bolt that could be loosened to move the fan belt tightness. I probably tightened the belt just a little - it was hard using a crow bar to push it away from the engine.

So it is supposed to rain off and on here for the next 4 days. I'll take the tractor out for bush hogging work which always resulted in that gradual overheating pattern after things dry out in about a week.

My next move if it still overheats will be to cut out the inside of the thermostat to fashion a "restrictor", or maybe remove it altogether. The logic of coolant flowing too quickly through a radiator to transfer heat to the atmosphere...I dunno about that. With restricted flow the coolant spends more time inside the engine - the other side of the equation - so it would seem logical that the possible reduction in heat transfer in the radiator would be at least partially balanced by coolant less hot coming from the engine.

I know diesel engines need to run hot to be efficient. If I take out the thermostat it will be interesting to see how much longer it takes to move the temperature gauge to the normal band - or if it even gets there. I think it will be worth the experiment - and I don't use my tractor in the winter time anyway.

I'll report back - and thanks again to all the people who offered advice.

 

[Alan46]

I hope so. Yesterday I blew it all out again with compressed air - and after only doing 45 minutes of work a few days ago was surprised how much of that brown dust was still in there. Then I sprayed that Nu-Calgon Evap Foam - used the whole large spray can - let it fulminate (it goes on white foam, then sorta liquifies and runs clear) for 20 minutes, and then rinsed it all out.

I also did my best to tighten the fan belt. With great effort I could turn the fan a bit without the belt moving, but it also was tight enough to turn the belt too. I did find a loose bolt at the lower engine side of the alternator, but that wasn't the bolt that could be loosened to move the fan belt tightness. I probably tightened the belt just a little - it was hard using a crow bar to push it away from the engine.

So it is supposed to rain off and on here for the next 4 days. I'll take the tractor out for bush hogging work which always resulted in that gradual overheating pattern after things dry out in about a week.

My next move if it still overheats will be to cut out the inside of the thermostat to fashion a "restrictor", or maybe remove it altogether. The logic of coolant flowing too quickly through a radiator to transfer heat to the atmosphere...I dunno about that. With restricted flow the coolant spends more time inside the engine - the other side of the equation - so it would seem logical that the possible reduction in heat transfer in the radiator would be at least partially balanced by coolant less hot coming from the engine.

I know diesel engines need to run hot to be efficient. If I take out the thermostat it will be interesting to see how much longer it takes to move the temperature gauge to the normal band - or if it even gets there. I think it will be worth the experiment - and I don't use my tractor in the winter time anyway.

I'll report back - and thanks again to all the people who offered advice.

Just a thought…..Can you go to a thermostat that opens sooner, like maybe 10 degrees?

I had an issue years ago with a drag car that would run hotter than I wanted, so I went to a 160 thermostat from a 180 that did the trick. It had a 4 row aluminum radiator cooling a 427 sb with 650+ hp.

 

[Williy]

A thermostat is designed to keep the engine at a certain temp
to run efficently

willy

 

[LouNY]

I hope so. Yesterday I blew it all out again with compressed air - and after only doing 45 minutes of work a few days ago was surprised how much of that brown dust was still in there. Then I sprayed that Nu-Calgon Evap Foam - used the whole large spray can - let it fulminate (it goes on white foam, then sorta liquifies and runs clear) for 20 minutes, and then rinsed it all out.

I also did my best to tighten the fan belt. With great effort I could turn the fan a bit without the belt moving, but it also was tight enough to turn the belt too. I did find a loose bolt at the lower engine side of the alternator, but that wasn't the bolt that could be loosened to move the fan belt tightness. I probably tightened the belt just a little - it was hard using a crow bar to push it away from the engine.

So it is supposed to rain off and on here for the next 4 days. I'll take the tractor out for bush hogging work which always resulted in that gradual overheating pattern after things dry out in about a week.

My next move if it still overheats will be to cut out the inside of the thermostat to fashion a "restrictor", or maybe remove it altogether. The logic of coolant flowing too quickly through a radiator to transfer heat to the atmosphere...I dunno about that. With restricted flow the coolant spends more time inside the engine - the other side of the equation - so it would seem logical that the possible reduction in heat transfer in the radiator would be at least partially balanced by coolant less hot coming from the engine.

I know diesel engines need to run hot to be efficient. If I take out the thermostat it will be interesting to see how much longer it takes to move the temperature gauge to the normal band - or if it even gets there. I think it will be worth the experiment - and I don't use my tractor in the winter time anyway.

I'll report back - and thanks again to all the people who offered advice.

How much more sludge came out with the cleaner?
Be careful of tightening a fan belt too much, too tight will take out water pump and alternator bearings. Alternators are just kind of expensive and not bad to replace, water pumps can be very expense and a royal pain to replace.

 

[EddieWalker]

Did you use the hose to flush out the cleaner that you applied? It's odd that so many people don't want to use a hose on their radiator because they think it will create mud, or the dust will build up from moisture, but nobody refuses to drive in the rain for that same reason.

It sounds like your fan belt is nice and tight.

Since you are still getting dirt out of your radiator, you really need to get the hose out and get it all cleaned out.