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Discussion Starter #1
I was blowing snow today and my x728 starts overheating. I burped the cooling system to no effect. The radiator is stone cold so I'm suspecting a stuck thermostat. In every other engine I've ever seen the thermostat is located at the return hose that connects at the top of the radiator. This way it senses the water temperature as it exits the engine and reacts accordingly. However, the Kawasaki 750d has the thermostat located at the supply hose from the bottom of the radiator where the cooled water is entering the engine. Does this make sense or am I missing something here?
 

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Discussion Starter #2
Problem solved, bad thermostat. However, I'm still confused by Kawasaki's decision to put the thermostat at the coolant supply to the engine. Strange.
 

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If I had to guess, as I haven't really studied the coolant system on the engine.

The location of the thermostat (I'm guessing here) is for one or more of a few possible reasons.

1) the location is easier to fit into the overall engine design making it cheaper to build and or more compact in design as opposed to putting it in another location.

2) the flow of the engine coolant may be reverse of what you are thinking and the hot engine water is entering the bottom of the radiator and no the top.

3) placing the thermostat low on the engine and in the return stream helps the engine heat up quicker and stay at higher operating temps when the engine is lightly loaded. The warmer a gasoline engine runs the more fuel efficient it becomes. By delaying the opening of the thermostat until the engine really needs the radiator to cool off should help with improving fuel economy and reduce emissions in a lightly loaded engine. The majority of the time our tractor engines are running in light load conditions.
 

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Problem solved, bad thermostat. However, I'm still confused by Kawasaki's decision to put the thermostat at the coolant supply to the engine. Strange.

That was my guess, how hard was it to change?
 

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If I had to guess, as I haven't really studied the coolant system on the engine.

The location of the thermostat (I'm guessing here) is for one or more of a few possible reasons.

1) the location is easier to fit into the overall engine design making it cheaper to build and or more compact in design as opposed to putting it in another location.

2) the flow of the engine coolant may be reverse of what you are thinking and the hot engine water is entering the bottom of the radiator and no the top.

3) placing the thermostat low on the engine and in the return stream helps the engine heat up quicker and stay at higher operating temps when the engine is lightly loaded. The warmer a gasoline engine runs the more fuel efficient it becomes. By delaying the opening of the thermostat until the engine really needs the radiator to cool off should help with improving fuel economy and reduce emissions in a lightly loaded engine. The majority of the time our tractor engines are running in light load conditions.
From what I know of the Kawasaki engines, I would have to go with your Door Number 3......Also, there are hundreds of thousands if not millions of Kawasaki engines which are air cooled running in a wide variety of machines, including zero turns, L&G tractors, etc. Kawasaki must have the engine designed to handle the heat of operation very well and when a radiator is utilized, I would imagine they don't need the full capacity of it at all times like other engines which must be liquid cooled.

And my thoughts are purely my speculation, but of your three choices, number 3 seems to fit the best with how I see the situation......:good2:

Speculating on a speculation.......hey, this could now make the news as that's often how they "report" things now. The days of "verify, verify and two independent sources" seems to have been eliminated by many of the "news organizations" and now they seem to live off of tweets and other rumors instead. At least we both mentioned we are simply speculating.......:laugh::lol:
 

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From what I know of the Kawasaki engines, I would have to go with your Door Number 3......Also, there are hundreds of thousands if not millions of Kawasaki engines which are air cooled running in a wide variety of machines, including zero turns, L&G tractors, etc. Kawasaki must have the engine designed to handle the heat of operation very well and when a radiator is utilized, I would imagine they don't need the full capacity of it at all times like other engines which must be liquid cooled.

And my thoughts are purely my speculation, but of your three choices, number 3 seems to fit the best with how I see the situation......:good2:

Speculating on a speculation.......hey, this could now make the news as that's often how they "report" things now. The days of "verify, verify and two independent sources" seems to have been eliminated by many of the "news organizations" and now they seem to live off of tweets and other rumors instead. At least we both mentioned we are simply speculating.......:laugh::lol:
I would also lean very heavily towards #3 being the true reason.

Would this count as a 3rd step verification making this a cold hard reportable fact that can't be argued with?
 

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I would also lean very heavily towards #3 being the true reason.

Would this count as a 3rd step verification making this a cold hard reportable fact that can't be argued with?
Sure, we can roll with that.......:thumbup1gif: We just did more verification between us, than many of the "major media" networks seem to bother with anymore.......
 

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Actually the designer put his scribbles in the copy machine upside down and then sent the copy to engineering witha note "build this" :laugh:
 

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Discussion Starter #9
That was my guess, how hard was it to change?
The hardest part was draining the anti-freeze. I learned after the fact that there is a drain plug in the thermostat housing, but once removed there's not a clear space to collect the fluid so it just splashes against the frame. After that, it's a matter of removing two bolts that hold the housing to the block and then three more to remove the thermostat. 15-20 minutes to remove and replace.
 

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If I had to guess, as I haven't really studied the coolant system on the engine.

The location of the thermostat (I'm guessing here) is for one or more of a few possible reasons.

1) the location is easier to fit into the overall engine design making it cheaper to build and or more compact in design as opposed to putting it in another location.

2) the flow of the engine coolant may be reverse of what you are thinking and the hot engine water is entering the bottom of the radiator and no the top.

3) placing the thermostat low on the engine and in the return stream helps the engine heat up quicker and stay at higher operating temps when the engine is lightly loaded. The warmer a gasoline engine runs the more fuel efficient it becomes. By delaying the opening of the thermostat until the engine really needs the radiator to cool off should help with improving fuel economy and reduce emissions in a lightly loaded engine. The majority of the time our tractor engines are running in light load conditions.
If the coolant flow was from the top of the radiator to the bottom any time the radiator was anything but completely full (ie, submerging the top radiator hose), the water pump would be sucking air and cavitate. Theoretically, it would work, but practically speaking, it would be a huge design fault.
 
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