First coolant change questions L3901

louky1150

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L3901
Jul 27, 2020
2
0
1
Southern Indiana
I'm behind on changing my coolant on this 5 year old, 180 hour tractor. I didn't realize this coolant change was time related rather than hour related. I've been looking at some Youtubes on this change, seems to call for draining, adding distilled water and flushing, redraining, and filling with 50/50 coolant. What I am not understanding: It seems like this would leave the mix at less than 50% because you would be left with some of the distilled water in the block after you drain it out of the radiator. What am I missing?

I'd also like some opinions on using an additive in the flushing process, and recommendations for brands.

Thanks in advance!
 

je1279

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I'm behind on changing my coolant on this 5 year old, 180 hour tractor. I didn't realize this coolant change was time related rather than hour related. I've been looking at some Youtubes on this change, seems to call for draining, adding distilled water and flushing, redraining, and filling with 50/50 coolant. What I am not understanding: It seems like this would leave the mix at less than 50% because you would be left with some of the distilled water in the block after you drain it out of the radiator. What am I missing?

I'd also like some opinions on using an additive in the flushing process, and recommendations for brands.

Thanks in advance!
It sounds like they are flushing the system also before adding the new coolant. I dont think that is necessary with only 180 hours on your tractor. I would just drain the existing coolant and refill with an approved 50/50 mix. If you choose to flush it, the small amount of water that remains in the system will not be a problem unless you are in the absolute coldest of climates.
 
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ayak

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L3301 HST
Feb 16, 2018
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I’ll let others speak to your specific question, but when I did this about a year ago on my 3301 (so likely similar parts, but check), I found the radiator plug (if used to drain there) should be replaced - not reused. You can see how where the two mating surfaces come together, it cuts into the gasket and it’s unlikely you’ll make a good connection again if reusing that plug. Shown here are the used plug and the one I ordered in when I couldn’t stop a slow drip. Later I saw where others were said to be disconnecting a hose instead but I was already past that point.
B78557D9-B67A-4A7C-A588-0ACC352DD304.jpeg
DD943BED-9574-4D6A-BBDF-C61D4EAFE3C3.jpeg
F1BC820E-8C54-4F72-B6D0-3BDF46463446.jpeg
 

85Hokie

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Jul 13, 2013
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the thing about 50-50 is somewhat misleading - THE reason it is labeled 50-50, because that is almost idiot proof ......

it is hard to even buy straight antifreeze now days - comes 50-50 from the bottle and costs the same!

In actual terms a ratio of 60-40 is better for super cold weather - 50-50 is almost as good but a lot easier to do the math.

AND this is even a little crazier - as you INCREASE the ratio - the boiling point does go up too - but the cooling ability goes down quite a bit too. SO a 50-50 is the easiest and somewhat best ratio for the average non math person to do and get right!

IF you lives on the equator - you still might need it NOT to boil over, but a smaller ratio like 10-90 or 20-80 would be better, since the more water cools better than the antifreeze side. Pure water cools better than any ratio of antifreeze agents - but that does not protect from rust and all those little things most never think about.

Bottom line - unless you have gallons left in the system - you pour in 50-50 and your ratio might be watered down but still very effective.

The best tool is to either check via a volt-ohm meter or do a density test - both will tell you what is good and not good about the ratio.

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Njtool

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Lx2610 HSDC. BH77 backhoe
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Service it the best you can. Most people never change coolant until the radiator leaks. If you want to go the extra mile, it will give you piece of mind that you’ve done everything possible to prevent wear and tear on your machine.

I would pick up a cheap tester to give yourself piece of mind too.

On a side note. Antifreeze is also a lubricant for the water pump. Running mostly water will cause premature water pump failure, even at the equator, not to mention increases oxidation in the coolant system
 

GeoHorn

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The amount of water left in the system after using water to flush and drain between draining out the old and installing the new antifreeze-mixture is UN-important. As time accrues some small amounts of water will evaporate in most systems and guess with what it should be replenished?
(Water)

If larger amounts are lost thru a leaking hose-clamp, etc., then replace the lost fluid with 50/50 mix.

Worrying about the small amount of water left by a flushing exercise is unavailing. (In fact, if the same type of antifreeze is installed, I doubt if it’s actually beneficial to flush the system at all between changes. The only reason to flush a healthy system is to prevent adverse reactions between different types or brands.)
 
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mcfarmall

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Kubota M5660SUHD, Farmall C
Sep 11, 2013
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Five years old and only 180 hours? It's a tractor not a garage decoration! I'm just funnin'
 

BobInSD

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L5740
Jun 23, 2020
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...

Bottom line - unless you have gallons left in the system - you pour in 50-50 and your ratio might be watered down but still very effective.
In a cold climate it's a little more important. I need to be 50-50 or better (shoot for 55-60% anti-freeze/45-40% water). What I do is drain and flush a couple of times, then look up the stated capacity of the cooling system. Multiply that by .6 (or .5 in VA) and put that much straight antifreeze in. Then I top off w/ distilled water, bring it up to temp, let cool, top off with distilled water. Maybe repeat, but just adding distilled until I'm convinced it's full. On a car I make sure the overflow tank is clean and put 60-40 in it also. Once I'm sure it's bled and full, any coolant that gets added later is 50-50.

Disclaimer: Never done this on a Kubota, but what I do with my vehicles and other tractors.

...

Worrying about the small amount of water left by a flushing exercise is unavailing. (In fact, if the same type of antifreeze is installed, I doubt if it’s actually beneficial to flush the system at all between changes. The only reason to flush a healthy system is to prevent adverse reactions between different types or brands.)
I don't know about Kubota, but I've had vehicles that kept a few quarts after draining. You know, the ones that they should have put a separate drain in the block but didn't. I take the bottom hose off, but there's still a lot in there.

When I say "flush" I mean fill with distilled and drain, fill with distilled, bring up to temp, let cool, and drain. Not a pressure flush (unless the coolant is downright grody).
 

Cathy Liebchen

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Equipment
KUBOTA L3901, MX5800, MULE PRO FX, MULE PRO FXT
I’ll let others speak to your specific question, but when I did this about a year ago on my 3301 (so likely similar parts, but check), I found the radiator plug (if used to drain there) should be replaced - not reused. You can see how where the two mating surfaces come together, it cuts into the gasket and it’s unlikely you’ll make a good connection again if reusing that plug. Shown here are the used plug and the one I ordered in when I couldn’t stop a slow drip. Later I saw where others were said to be disconnecting a hose instead but I was already past that point.
View attachment 55450 View attachment 55451 View attachment 55452
Never remove this plug, ours stripped off and it was an ordeal to replace it, just remove the lower hose to drain
 

PoTreeBoy

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Mar 24, 2020
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Never remove this plug, ours stripped off and it was an ordeal to replace it, just remove the lower hose to drain
On my L35 there's a small hose running from the lower radiator to the block near the oil filter. If yours has one, pulling it off drains the block and radiator.
BTW, what's the acceptable way to dispose of the old coolant?
 

SDT

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multiple and various
Apr 15, 2018
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SE, IN
I'm behind on changing my coolant on this 5 year old, 180 hour tractor. I didn't realize this coolant change was time related rather than hour related. I've been looking at some Youtubes on this change, seems to call for draining, adding distilled water and flushing, redraining, and filling with 50/50 coolant. What I am not understanding: It seems like this would leave the mix at less than 50% because you would be left with some of the distilled water in the block after you drain it out of the radiator. What am I missing?

I'd also like some opinions on using an additive in the flushing process, and recommendations for brands.

Thanks in advance!
It is important that you change the coolant periodically because, though the freeze protection of the coolant lasts indefinitely, the anti corrosion protection does not.

Some engines have a block drain (that is accessible), others do not. If yours does not, you cannot drain all of the coolant.

I never buy premixed anti freeze because I have yet to see any such labels specifying that it is mixed with distilled water, and I will not put tap water in a cooling system. Distilled water may be used but until I see premix so labeled I will not use it.

I drain all that I can into a container before refilling with concentrated anti freeze amounting to about 50% of what was removed before filling the rest of the way with distilled water. To guild the lily, I remove the surge tank, thoroughly wash it out, and fill it to the normal/cold mark with non premixed antifreeze.

Do not use commercial radiator flush chemicals unless you like to replace leaking water pumps.

SDT
 

ItBmine

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B2620, RTV-X1100C
Jan 21, 2014
1,328
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Canada
I just used Peak Global extended life. Did not have to flush and the Peak Global mixes with all coolants, green or extended life. And as long as it is 70% it still performs the same as if it was 100%.

It's good for 12 years if checked with their test strips.

They were very good at answering all questions when I called them.
 

mattwithcats

Active member
Jun 17, 2017
772
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28
Virginia
Do the math...

A gallon of premixed 50/50 coolant - $10
A gallon of full strength - $12.50
A gallon of distilled water - $1

Two gallons premix - $20
Gallon full strength and a gallon distilled - $12.50 + $1 = $13.50
 

ayak

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L3301 HST
Feb 16, 2018
568
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WV
Deionized and Distilled while often used interchangeably, are two different processes. And while Distilled (boiled and then re-condensed) may be somewhat effective at reducing minerals in Water, I’ll take Deionized Water over Distilled any day when given the choice, as it’s going after dissolved mineral salts specifically. The conductivity specification in DI water is usually much better (higher resistance). It’s a lack of conductivity which helps with corrosion.
 
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marklbota

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B2710
Jan 30, 2021
15
2
3
Chicago Suburbs
The drain cock on my cooling system is connected to both the bottom of the radiator and to the block. When it's opened, it drains both. I've found that compressed air also helps get the last bits of coolant out of the system. I stretch a heavy piece of inner tube rubber over the radiator cap opening, poke a hole in the center and stick the nozzle from my air blow gun through the hole to make a poor man's seal. With the pressure set to 5-10psi I use the air to purge what's left in the system out the drain cock. That gets an extra bit to come out. The air can't blow into the top hose because the thermostat is closed, but it does pressurize the engine passageways through the lower hose. I fill the radiator with distilled water and flush it but don't use chemicals. I fill with coolant and leave the drain cock open until I see what comes out change from water to coolant.

If you don't have a drain cock, I guess the best you can do is remove the lower radiator hose and let that drain both the radiator and the block. The hose is at a low point on the engine, it should allow most of the coolant to drain.

I test my coolant every year with test strips, you can get them at NAPA or online. They measure how much additive is left in the coolant. The manual calls for 2 year changes, I've found mine goes 4-5 years before I see the beginning of a decline in additive, so I change it every 4-5 years. You can also send the coolant into a place like Blackstone labs and they'll tell you exactly what state the coolant is in.

Hydrometers are useless for measuring temperature protection, you need a refractometer. I took an auto repair class at the local community college, they had a dozen hydrometers to demonstrate that none of them worked, they weren't closer than 10 degrees.
 

GeoHorn

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Do not use commercial radiator flush chemicals unless you like to replace leaking water pumps.

SDT
I can vouch for THAT!... SDTs’ statement is “right-on”!
In the 50+ years I’ve owned vehicles I used commercial radiator-flush (Major brand) and lost the water pumps shortly thereafter.... After the THIRD time I finally put two-and-two together and realized what I was doing wrong.
In the last 40 years I’ve never used a “radiator-flush” product since...only plain tap-water from the garden hose if I flushed at all..... and have never lost a water pump after changing coolant. I’m writing of 14 different vehicles which I can confirm this statement is true.

If you remove the lower radiator hose... May I suggest you CHANGE THE HOSE and clamps while you’re at it...? 5-10 years should be considered the lifetime of most rubber hoses that handle hot or flammable fluids, if they are disassembled.