Radiator fan cycling heavy in reverse

[jaketheram]

Any luck tracing this issue?

Quick question: does the transmission get hot? When running, can you put your hand on the case comfortably?

Since the HST controls direction and flow, this would be my first place to look. You checked fluid, filters were replaced recently. What about the pedals? Maybe the adjustment is out. Is there ever a hint of this behavior when traveling forward?

Thanks for checking in.

Actually tonight was the first time I was back on it, we had a few inches of light snow. I did mean to put a hand on the HST but by the end of blowing my hands were frozen pretty bad, couldn't find my gloves and wanted to get done before dark.

I think you may be onto something with the pedals- reverse has always felt a tad slow, and today it seemed to lose "power" or speed in reverse without encountering any type of grade and blowing very little amount of fluffy snow, not sure this is pedal adjustment but something just doesn't seem right with reverse.

It never seems slow or to lose power in forward.

However, I think I may have been mistaken initially, the radiator fan isn't spooling up, it actually seems to be shutting down, and what I thought was it spooling up was it just kicking back on. Today it happened once in forward early on and I think once in reverse, where the fan shut off seemingly entirely for a brief period before spooling back up.

Definitely seems to be the radiator fan- not the HST fan.

But I am still confused about how either fan could change speed. As pointed out by someone's earlier post, the radiator fan is belt driven by the engine, and the HST fan seems to be attached to the driveshaft, so not sure how either of those things can shut down without the engine or driveshaft stopping spinning.

 

[ericm979]

Some cars and trucks have electric fan clutches since at speed there's plenty of air flow without the fan. Seems unlikely that a slow speed vehicle like a tractor would have a fan clutch but it's possible.

A weird thought- could the fan be rubbing on the shroud when the engine shifts on it's mounts? Maybe there's a loose or broken motor mount.

 

[mcfarmall]

Never seen a SCUT, CUT or any other farm tractor with an electric fan. Concrete trucks, wheel loaders, and skid loaders yes, but never a tractor.

Can you post a picture of the electric radiator fan on your tractor?

 

[jaketheram]

Never seen a SCUT, CUT or any other farm tractor with an electric fan. Concrete trucks, wheel loaders, and skid loaders yes, but never a tractor.

Can you post a picture of the electric radiator fan on your tractor?

I'm not sure if your question is directed at me, but I think I've mentioned several times since my initial incorrect assumption that the radiator fan is belt driven off the engine. That's why in my last couple posts I have been looking for peoples' input in to how/why the radiator fan shuts down briefly (3-15 seconds) before spooling back up.

As far as the HST slowdown, thanks to @crashz , I did some googling for pedal adjustment Kioti and what came up instead was a fairly common issue for these Kiotis to get bent reverse pedals that reduce the allowable travel. I checked last night and this certainly seems to be the case with mine, it's only an inch off the deck, so I will try bending that back or having dealer order me a new one since it is still under warranty. So thanks for getting me on the right path with that as far as reverse speed, but it appears to be a different issue from the fan.

The mystery still remains about how its even possible for the radiator fan to shut down. I will check engine mounts, but I think if it was hitting its shroud, I would here the THWAP THWAP THWAP of the blades making contact before their motion was stopped, which I don't, but I will check the mounts as well as the inside of the shroud for signs of contact from the fan blades.

Attached is the only diagram from the service manual that shows the fan assembly.

 

[07wingnut]

If the fan is slowing down and the engine speed doesn't drop at the same rate as the fan slows down, then you have a belt slippage problem. That is usually caused by something binding, and if there is no noise from the fan hitting something, this points to an idler pulley starting to seize up, or your water pump doing the same. Loosen the belt and see if idler and water pump rotate smoothly.

 

[jaketheram]

If the fan is slowing down and the engine speed doesn't drop at the same rate as the fan slows down, then you have a belt slippage problem. That is usually caused by something binding, and if there is no noise from the fan hitting something, this points to an idler pulley starting to seize up, or your water pump doing the same. Loosen the belt and see if idler and water pump rotate smoothly.

Thanks, I will check that out. From my memory, there is only 3 pulleys on the belt. The Fan, the alternator, and what must be the water pump. I'll loosen the belt and make sure they all spin freely.

 

[07wingnut]

You probably already know this, but just in case, note that the fan is mounted on the waterpump shaft.

 

[crashz]

Glad you have the HST / reverse issue solved.

The radiator fan is solidly mounted to the water pump flange and driven by the belt. Any change in speed without change in engine speed would be belt slippage as 07 mentioned. i saw no clutch mechanism in the parts diagram you posted. Or its remotely possible that the fan center is broken.

The first thing I'd check is the belt tension, and see of the fan can move freely when the engine is off. If the fan moves under finger pressure, the belt is either not tight or glazed to the point of failure. Most importantly is that the water pump may not be spinning when the fan cuts out, so you could have a real overheating issue there.

Your machine is new, so a little belt stretch isn't unreasonable.