Cooling Problems

BX25Dave

New member

Equipment
BX25DLB
Sep 3, 2023
18
3
3
Colorado
Hey Everyone, I have a 2015 BX25D. When I go to use it to mow etc., It is getting hot, with sometimes 2 dots above the normal 3 on the gage. This last time, I opened the radiator (I always check it before running) and it took about 1 1/2 quarts of coolant. There is no liquid in the oil and all the maintenance has been completed. It did this once before and I changed the thermostat and that seemed to help until now. Nothing is coming out of the overflow tube. Anyone have any suggestions as to what would be eating all the coolant?
 

85Hokie

Moderator
Staff member
Lifetime Member

Equipment
BX-25D ,PTB. Under Armor, '90&'92-B7100HST's, '06 BX1850 FEL
Jul 13, 2013
10,745
2,551
113
Bedford - VA
Have you cleaned the pull out screen ?

Have you cleaned the radiator outside well?

Where does the gauge run when you are not cutting grass?
 

D2Cat

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Lifetime Member

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L305DT, B7100HST, TG1860, TG1860D, L4240
Mar 27, 2014
13,812
5,545
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40 miles south of Kansas City
To really clean a radiator a product like Simple Green all purpose cleaner onto the radiator fins, let it soak for a few minutes, then rinse. A layer of dirt gets attracted and attached creating a less efficient radiator.
 
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Grandad4

Active member

Equipment
1949 Farmall M, previously owned: L 4610, BX 2230
Apr 5, 2016
323
79
28
Greensboro, NC
Ditto above comments about cleaning the actual radiator fins even if the screen is clear. Mowing brings very fine chaff onto the fins where it is not easily visible. Taking a few minutes to do this every month or so during mowing season will help keep the rad clean and cool.
 
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The Evil Twin

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Equipment
L2501, LA526,
Jul 19, 2022
2,814
2,825
113
Virginia
First of all, welcome!
Firget about cleaning the radiator. If you added 1.5 quarts of coolant between uses, it's either leaking it or burning it. Those are the only options. That is over 10% of the total charge.
 
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S-G-R

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Lifetime Member

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LX3310
Jun 17, 2020
1,111
2,251
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PEI Canada
To really clean a radiator a product like Simple Green all purpose cleaner onto the radiator fins, let it soak for a few minutes, then rinse. A layer of dirt gets attracted and attached creating a less efficient radiator.
I'm a big fan of Simple Green but never thought of using it on the rad.
 

imnukensc

Well-known member

Equipment
BX2380
Sep 10, 2015
687
590
93
Midlands of SC
In addition to the above recommendations for cleaning the radiator, a few years ago Kubota sent out new caps for the overflow tank since some original caps were blocked. Did you get one? Just another thing to check.
 

BX25Dave

New member

Equipment
BX25DLB
Sep 3, 2023
18
3
3
Colorado
Have you cleaned the pull out screen ?

Have you cleaned the radiator outside well?

Where does the gauge run when you are not cutting grass?
The radiator and screen are both clean. I check tose on a regular basis. I changed the thermostat several months ago (with an OEM one), still did not stop the overheating. The guage usually runs about 3 dots. Anytime I engage a implement (doesn't make any difference what it is) the gauge goes up to 4 dots, and I start watching closely. When it reaches 5 dots (2 below the max) I shut it off immediately and park it until it cools down. Then check the radiator fluid and it's low. Nothing is coming out of the reservoir, but the radiator is losing the coolant someplace and I don't know where. At this point I'm thinking a blown head gasket, but nothing in the exhaust indicates coolant there. So I am at a loss. Thanks for your help!
 

nbryan

Well-known member

Equipment
B2650 BH77 LA534 54" ssqa Forks B2782B BB1560 Woods M5-4 MaxxHaul 50039
Jan 3, 2019
1,231
763
113
Hadashville, Manitoba, Canada
Make sure that ALL the rad hose clamps are tight. I had mystery coolant loss for about a year with my new B2650, and could occasionally smell that hot coolant smell while operating, but never found a leak. it turns out that rad hose clamps had "settled in" or something and I could twist the hoses at a few clamp locations, obv not tight enough. So while hot, the system wasn't ever getting up to pressure and was leaking hot antifreeze onto the engine and was evaporating instantly, so not easily visible.

A round of rad hose clamp tightening and the coolant loss stopped.
 
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The Evil Twin

Well-known member

Equipment
L2501, LA526,
Jul 19, 2022
2,814
2,825
113
Virginia
When you shut it off hot, where is the coolant level in the reservoir?
When it is stone cold, where is the level in the reservoir?
I'm starting to think your rad cap is shot. But that wouldn't explain where the coolant is going. You are adding A LOT of coolant. It could be pushed out of the reservoir overflow and not know it. Attach a clear tube to the reservoir overflow and bend it like a U before it exits the machine. That will trap a portion of the coolant if its getting pushed out that way.
have the cap tested.
Do a vacuum or pressure test on the cooling circuit. Vacuum will tell you if it's leaking. Pressure will tell you where, if it is.
 

BX25Dave

New member

Equipment
BX25DLB
Sep 3, 2023
18
3
3
Colorado
May try removing the battery and clean the (vacuum)radiator?
Worked on a friends BX25D several years !
Good Luck!
Thanks for the suggestion. did as you said, really nothing behind or under the battery, generally clean. Thanks!
 
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BX25Dave

New member

Equipment
BX25DLB
Sep 3, 2023
18
3
3
Colorado
When you shut it off hot, where is the coolant level in the reservoir?
When it is stone cold, where is the level in the reservoir?
I'm starting to think your rad cap is shot. But that wouldn't explain where the coolant is going. You are adding A LOT of coolant. It could be pushed out of the reservoir overflow and not know it. Attach a clear tube to the reservoir overflow and bend it like a U before it exits the machine. That will trap a portion of the coolant if its getting pushed out that way.
have the cap tested.
Do a vacuum or pressure test on the cooling circuit. Vacuum will tell you if it's leaking. Pressure will tell you where, if it is.
Thanks for the info. The reservoir is 3/4 full when I start, but when it gets hot it is empty. I'll get a new radiator cap. The recall on the reservoir cap has been done, so that should not be an issue with that one.
 
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BX25Dave

New member

Equipment
BX25DLB
Sep 3, 2023
18
3
3
Colorado
When you shut it off hot, where is the coolant level in the reservoir?
When it is stone cold, where is the level in the reservoir?
I'm starting to think your rad cap is shot. But that wouldn't explain where the coolant is going. You are adding A LOT of coolant. It could be pushed out of the reservoir overflow and not know it. Attach a clear tube to the reservoir overflow and bend it like a U before it exits the machine. That will trap a portion of the coolant if its getting pushed out that way.
have the cap tested.
Do a vacuum or pressure test on the cooling circuit. Vacuum will tell you if it's leaking. Pressure will tell you where, if it is.
I hooked a little bottle to the overflow tube to see if coolant was coming out. none seen there and the funny thing is that I don't smell coolant. I'll find someone to do the pressure/vacuum checks, I don't have the equipment to do so, excellent suggestion, Thanks!
 

BX25Dave

New member

Equipment
BX25DLB
Sep 3, 2023
18
3
3
Colorado
Have you cleaned the pull out screen ?

Have you cleaned the radiator outside well?

Where does the gauge run when you are not cutting grass?
Pull out screen and radioator cleaned before and after each use. All clean there. The guage runs at about 3 dots when just driving. When as load is put on it either the brush hog or the under deck mower, the gage starts going up. It stays at 4 dots for a long (about 15 minutes) time, then moves to 5 dots (1 below max) that's when I shut it down. Thanks for the comments!
 

BX25Dave

New member

Equipment
BX25DLB
Sep 3, 2023
18
3
3
Colorado
In addition to the above recommendations for cleaning the radiator, a few years ago Kubota sent out new caps for the overflow tank since some original caps were blocked. Did you get one? Just another thing to check.
Yep, I got one when they came out and replaced it. Thanks
 

BX25Dave

New member

Equipment
BX25DLB
Sep 3, 2023
18
3
3
Colorado
Make sure that ALL the rad hose clamps are tight. I had mystery coolant loss for about a year with my new B2650, and could occasionally smell that hot coolant smell while operating, but never found a leak. it turns out that rad hose clamps had "settled in" or something and I could twist the hoses at a few clamp locations, obv not tight enough. So while hot, the system wasn't ever getting up to pressure and was leaking hot antifreeze onto the engine and was evaporating instantly, so not easily visible.

A round of rad hose clamp tightening and the coolant loss stopped.
Thanks, I went out and checked all the red clamps, all tight and no signs of coolant around them. The odd thing is that I don't smell coolant and there are no signs of it coming out the overflow hose. Thanks
 

BX25Dave

New member

Equipment
BX25DLB
Sep 3, 2023
18
3
3
Colorado
Have you cleaned the pull out screen ?

Have you cleaned the radiator outside well?

Where does the gauge run when you are not cutting grass?
The radiator screen and the radiator are cleaned each time i use it. The gaige runs about 3 dots in idle or just moving around. When an implement is engaged eith from the back or mid, it starts to heat up, slowly. About 1/2 hour later its in the high range and I shut it down. I have not have the lights come on, I wont let it get that hot. Thanks for the comments!
 

BX25Dave

New member

Equipment
BX25DLB
Sep 3, 2023
18
3
3
Colorado
To really clean a radiator a product like Simple Green all purpose cleaner onto the radiator fins, let it soak for a few minutes, then rinse. A layer of dirt gets attracted and attached creating a less efficient radiator.
When I was in the military we used to use simple green to clean the helicopters. But found out that simple green was a corrosive on aluminum. That was some time ago, I don't know if Simple Green has changed the formula, but I am wary of it. I do use a cleaner to get that layer of fine dirt found here in Colorado off and it seems to work good. Thanks for the excellent comment!
 

BX25Dave

New member

Equipment
BX25DLB
Sep 3, 2023
18
3
3
Colorado
First of all, welcome!
Firget about cleaning the radiator. If you added 1.5 quarts of coolant between uses, it's either leaking it or burning it. Those are the only options. That is over 10% of the total charge.
I agree, it is too much. I'm going to have it pressure/vacuum checked and see if I can find out what the issue is, I'm perplexed! Thanks