B7100 HST overheating

EZOilburner · May 8, 2019

I have a temperature gauge on the top coolant hose on the motor and mine is getting up to 220f consistently even on cold days. I have cleaned the rad (already in good shape) put new coolant, checked belt tension but this thing still gets hot. I keep the rpms high to help air flow but I was told some put a coolant pump in-line with the system to help circulate coolant, does anyone here know or have seem it? I will only get hotter so I want to have a backup plan for the cooling system on this tractor.

Thanks, EZ.

Dave_eng · May 8, 2019

The B7100 has a thermo-syphon system which performs very well with no water pump.

Have you checked the accuracy of the temp unit?

Are there other symptoms of overheating?

The usual rad issue is debris between the fins blocking air flow.

Those tractors had a whistle on the rad vent line to warn operators of overheating but most never heard it.

Overheat warning is a loud little whistle that is mounted on the front right frame and attached to the radiator neck by a hose.

Dave

EZOilburner · May 8, 2019

Yes the gauge is accurate, I need to do something to keep it from overheating.
I found this video, a little fabrication but possible, I heard some fit an electric pump.

https://www.youtube.com/watch?v=b0pRTG0Cflg

Btw I blow air on the rad after every use to make there never is anything in the way, I will pull the hoses and see if any are collapsing too. Thanks

85Hokie · May 8, 2019

EZOilburner said:
Yes the gauge is accurate, I need to do something to keep it from overheating.
I found this video, a little fabrication but possible, I heard some fit an electric pump.

Ok, first do not get OVERLY excited about that 220 F on the top of the radiator.......

the REAL and only question is .....what is the temperature AT THE bottom of the radiator?

I have two B7100's - one runs at 210 F at the top and that is the perfect temp!!!! But at the bottom of the very clean radiator....it shows about 130 or so. If I run the snot out of it....then after I allow it to idle.....goes to about 180 F and sits there till I cut the machine off.

So take some more readings ......catch the bottom of the metal neck on the radiator and report back.

The "fill" point is kinda funny too - too much liquid and it will puke it out.....I find about an inch down from the fill neck is about right.

On another note......don't use 50-50.... go with 70-30 water to antifreeze.....
water has a much higher heat dissipation than a 50-50 mix.....

EZOilburner · May 9, 2019

Thank you for replying I will check the temperature at the bottom but my feeling is I will have to flush the cooling system to make sure there's no the breeze getting in the way. I will also add this Stillwater to the mix as I am using 50/50 right now. I ran it again and it is actually getting hotter than 220 at the top and as you describe it is overfilled in mine as I filled it all the way to the top.
Thanks EZ

mattwithcats · May 9, 2019

I posted about this a while ago...

http://www.orangetractortalks.com/forums/showthread.php?t=37479

85Hokie · May 9, 2019

EZOilburner said:
Thank you for replying I will check the temperature at the bottom but my feeling is I will have to flush the cooling system to make sure there's no the breeze getting in the way. I will also add this Stillwater to the mix as I am using 50/50 right now. I ran it again and it is actually getting hotter than 220 at the top and as you describe it is overfilled in mine as I filled it all the way to the top.
Thanks EZ

AS for the need to add an aux pump.....
it can be done - has been done.....continues to be done.

but IF there is a problem of over heating.......

a electronic pump is a huge band-aide to fix a problem that is still a potential problem.

The flow through the radiator must drop the temp at least 50-70 degrees ......

if that is NOT doing that .....the radiator is at fault somehow.....and should be fixed

you could have a small pin hole in the head gasket too - in which case that needs to be fixed.

you could have an obstruction in the head/block too......

In my opinion - finding the true problem is a little easier than fixing a solution to the problem.

do tell us what you get at the bottom of the radiator.

Russell King · May 9, 2019

You say you have a clean radiator exterior but have you really inspected it from top to bottom? Some of the Kubota tractors will build up a lot of blockage near the bottom and it is hidden by the battery or other parts so that you really can’t see it very well at all.

You may want to remove the radiator and clean it off really well outside of the tractor so you are positive that it is clean.

Sent from my iPad using Tapatalk

EZOilburner · May 11, 2019

I will take the temperature at the bottom to see what is the drop now, then pull it and clean it well (I've already cleaned the outside thoroughly) in case there is any debris inside and check the temperature again.
Thanks for the tip, I already ordered a12v pump and temperature switch in case this doesn't help.

Russell King said:
You say you have a clean radiator exterior but have you really inspected it from top to bottom? Some of the Kubota tractors will build up a lot of blockage near the bottom and it is hidden by the battery or other parts so that you really can’t see it very well at all.

You may want to remove the radiator and clean it off really well outside of the tractor so you are positive that it is clean.

Sent from my iPad using Tapatalk

EZOilburner · May 18, 2019

I measured the temperatures on top and bottom of the radiator hoses and it does drop about 40F but the temps still get high when mowing. I also looked at the radiator inside (after pulling it) cleaned everything I could see but it still gets hot when the mower is used but the mower moves freely when not connected so I can't see something in particular that is causing it to overheat.

I installed an electric coolant pump with a temp switch to circulate the coolant when it is about 220f and it has worked very well since, the temps hover around 190f-220f. I had to get creative with the piping but it has worked well and keeps the temperatures from getting out of hand even after a couple hours running full load.

North Idaho Wolfman · May 19, 2019

EZOilburner said:
I measured the temperatures on top and bottom of the radiator hoses and it does drop about 40F but the temps still get high when mowing. I also looked at the radiator inside (after pulling it) cleaned everything I could see but it still gets hot when the mower is used but the mower moves freely when not connected so I can't see something in particular that is causing it to overheat.

I installed an electric coolant pump with a temp switch to circulate the coolant when it is about 220f and it has worked very well since, the temps hover around 190f-220f. I had to get creative with the piping but it has worked well and keeps the temperatures from getting out of hand even after a couple hours running full load.

If it gets any worse, your going to need to do a head gasket on it.

EZOilburner · May 20, 2019

North Idaho Wolfman said:
If it gets any worse, your going to need to do a head gasket on it.

Yep that's what I was thinking, I can't see any other explanation but also I noted that is only does it when powering the mower deck and not as much when using the loader.
Thanks again.

D2Cat · May 21, 2019

Revisit post #8 by Russell. That would be worth your while to save additional engine work.

Even spraying something like "Purple Power" cleaner and let it soak for a while and wash off. There is often particles of dust and grass seed that get in the fins and attached good enough they don't come out easily.

EZOilburner · May 24, 2019

D2Cat said:
Revisit post #8 by Russell. That would be worth your while to save additional engine work.

Even spraying something like "Purple Power" cleaner and let it soak for a while and wash off. There is often particles of dust and grass seed that get in the fins and attached good enough they don't come out easily.

Thanks for the reply, the radiator is spotless, no oil at all and very clean inside and out. I hope it isn't a HG but nothing else seems to be the problem and the curious thing is it only does it when using the mower but other times its fine.

Alexisferos · May 25, 2019

220 is a perfect working temp for that tractor.
For me you have another 10F until the yellow zone and 15F to hear the whistle.
http://www.orangetractortalks.com/forums/showthread.php?t=16639

philm · May 8, 2021

anyone know what le trick pumps others have installed to supplement the cooling system on B7100's ?

i live in Fl.and it very hot here i wouldn't mind cooling it a bit more

85Hokie · May 8, 2021

philm said:
anyone know what le trick pumps others have installed to supplement the cooling system on B7100's ?

i live in Fl.and it very hot here i wouldn't mind cooling it a bit more

Reduce the ratio of antifreeze - go 20-80 ...... antifreeze to water ........

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B7100 HST overheating

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