Cooling fan problem

[Rosohatica]

Hi, I have an old 1986. Kubota B1402. I started to notice sometimes the cooling fan wont start. I thought maybe it has thermostat and only starts when hot enough until one time recently it overheated and boiled (see the pic). Since then I check the fan before the work and use a stick to hand start it if it didnt on its own. See the video. Any suggestion how to fix it? The belt is not a problem, I tightened it.

 

[jaxs]

I can't say for certain what's wrong with the fan however I can tell you that you are risking catastrophic internal engine damage by running engine before it's fixed. Unlike gasoline engines that can overheat from time to time and not suffer much damage, diesels often crack head ,seize crankshaft bearings,melt pistons or a number of other issues which render engine to scrap iron during a single overheat. Until you can afford a new clutch assembly you might consider locking hub with screws so that fan runs at all times regardless of engine temperature.

 

[Rosohatica]

I can't say for certain what's wrong with the fan however I can tell you that you are risking catastrophic internal engine damage by running engine before it's fixed. Unlike gasoline engines that can overheat from time to time and not suffer much damage, diesels often crack head ,seize crankshaft bearings,melt pistons or a number of other issues which render engine to scrap iron during a single overheat. Until you can afford a new clutch assembly you might consider locking hub with screws so that fan runs at all times regardless of engine temperature.

Thanks. I havent noticed any damage so far thankfully. Overheating happened just once. Usually I check the fan if its spinning before intense work. This time I forgot. If I open the hood and its not spinning I use a stick to touch it and it starts going right away. So I am not sure if it is supposed to work right away when you turn on the engine, or it has a thermostat.Stick touching always gets it going.

 

[North Idaho Wolfman]

The fan is purely mechanical and should always turn when the engine is turning.
There is nothing that should stop it from turning.
You need to check the belt and remove the belt and check the dyno (what everyone things is a water pump) it should spin freely with magnetic sticky spots.

 

[Rosohatica]

What is the mentioned fan clutch for then if it should spin all the time?

The fan is purely mechanical and should always turn when the engine is turning.
There is nothing that should stop it from turning.
You need to check the belt and remove the belt and check the dyno (what everyone things is a water pump) it should spin freely with magnetic sticky spots.

 

[Russell King]

The B1402 is not a tractor with any information available in the USA so we can’t really know what is standard on your tractor.

But there is often a thermally controlled fan clutch used to control the power used by the fans on rear wheel drive cars. I don’t think that Kubota would need or use a clutch on their fans. First off they don’t need to worry about how much power the fan takes and the tractor speed is not high enough to cool the radiator off (like when a car is going 60 kph)

Here is some information about how the fan cluthes work.

Understanding Fan Clutches — and When it's Time to Replace Yours - OnAllCylinders

When you think of an automotive cooling system, the first thing that likely comes to mind is your radiator…or maybe your cooling fan. The oft-overlooked fan clutch doesn’t get a ton of credit …

www.onallcylinders.com

I would assume most European cars are front wheel drive and the radiator fans are probably electrically driven.

It is very odd that the fan on your tractor will not spin. I think the fan should be directly driven by the belt and the pulley. Therefore the fan seems to be somehow disconnected from the pulley hub. I would recommend you get a new fan and replace the one you have. I think you will be able to see what is wrong with it when you get it off.

 

[North Idaho Wolfman]

What is the mentioned fan clutch for then if it should spin all the time?

There is no fan clutch on that unit.
Watching the video I would say the belt has a bad spot in it or it's just too loose, and you need to tighten the tensioner on the side.

 

[GreensvilleJay]

hmm, tractor's from 1986..wonder how old the fan belt is !
Video shows it has a 'glazed' (shiny) spot or two on it.
Easy fix.... buy new ,properly sized belt for it. Should be a Metric belt not an American made 3lxxx or 4Lxxx belt. before installing, clean and degrease all 'pulleys' ! Usually install with 1/2" deflection at midpoint then next day or so, check and tighten .

 

[Rosohatica]

hmm, tractor's from 1986..wonder how old the fan belt is !
Video shows it has a 'glazed' (shiny) spot or two on it.
Easy fix.... buy new ,properly sized belt for it. Should be a Metric belt not an American made 3lxxx or 4Lxxx belt. before installing, clean and degrease all 'pulleys' ! Usually install with 1/2" deflection at midpoint then next day or so, check and tighten .

Hi, am not close to tractor at the moment but I looked at it at the moment the fan was not spinning. I thought the belt tension was not right but then one pulley on one side of the belt would spin while the fan side pulley would not, right? But they both were stationary and when I would move fan with the stick, everything started to spin. That is why I think the belt might not be a problem.

 

[Rosohatica]

There is no fan clutch on that unit.
Watching the video I would say the belt has a bad spot in it or it's just too loose, and you need to tighten the tensioner on the side.

How can I inspect for a clutch, just in case, to make sure there isnt one? And thermostat?

 

[North Idaho Wolfman]

How can I inspect for a clutch, just in case, to make sure there isnt one? And thermostat?

There is not a clutch, there is no provisions for such.
Grab the pulley behind the fan and grab the fan there are solidly connected together.
If there was a fan clutch then the fan pulley would always spin no matter what the fan clutch did.
It wouldn't stop spinning.
You have a bad or loose belt!
I don't believe on that model there is a thermostat either, there is also no water pump.
It's a thermosiphon system.

 

[Rosohatica]

There is not a clutch, there is no provisions for such.
Grab the pulley behind the fan and grab the fan there are solidly connected together.
If there was a fan clutch then the fan pulley would always spin no matter what the fan clutch did.
It wouldn't stop spinning.
You have a bad or loose belt!
I don't believe on that model there is a thermostat either, there is also no water pump.
It's a thermosiphon system.

Ok, thanks. Will check the belt once more.

 

[jaxs]

Nother ol boy had the same problem and someone suggested putting chalk marks on belt and pulley then posting a picture of chalk marks along with his question. After viewing video a feller way down on a South American peninsula pointed out engine wasn't running was the reason fan wasn't moving.

 

[Rosohatica]

There is not a clutch, there is no provisions for such.
Grab the pulley behind the fan and grab the fan there are solidly connected together.
If there was a fan clutch then the fan pulley would always spin no matter what the fan clutch did.
It wouldn't stop spinning.
You have a bad or loose belt!
I don't believe on that model there is a thermostat either, there is also no water pump.
It's a thermosiphon system.

Hi, just wanted to say you were right about everything. There is no clutch and the belt was totally worn out and cracked from the inside. I replaced it and now the fan makes so much wind it blows into my face where I seat.