No thermostat?

[skipmarcy]

No one addressed this aspect of the question. Is this part true? I ask because my 1510D start blowing warm air back from the radiator shortly after starting and I figured that the thermostat was stuck open, but I did not see any obvious place for it. The top hose connects directly to water pump without any obvious flange and thermostat housing. I have a 186 repair manual and the pics in there show a different outlet and an obvious thermostat housing.

Mike

I can't understand what difference it would make where the tractor was used in the world as to leaving the thermo. out. Different temp. ranges yes, but not controlling engine temp. at all seems very foolish. I can't think of a reason why they would leave it out of the system.

 

[Soundguy]

Any chance your yanmar was thermosyphon?

i know the 1700 is.. and can accept the pump from a 2000 as a conversion...

Soundguy

No one addressed this aspect of the question. Is this part true? I ask because my 1510D start blowing warm air back from the radiator shortly after starting and I figured that the thermostat was stuck open, but I did not see any obvious place for it. The top hose connects directly to water pump without any obvious flange and thermostat housing. I have a 186 repair manual and the pics in there show a different outlet and an obvious thermostat housing.

Mike

 

[john_bud]

I just read that tractors don't need thermostats. It said none of the overseas models have them, only U.S. models. I have a John Deere 950 with a diesel engine. If the thermostat is not necessary I would rather remove it. I've heard that on gasoline cars they are necessary for some reason.

Yeah, and I just read on the internet that politicians don't need brains!

Well, I guess some internet rumors are true after all....


But you do need thermostats, especially on diesels to get them up to correct operating temperature for complete combustion. Hot diesel engines run more effieciently than cold or cool engines.


Gas engines are heated up so that the emissions control equipment can be tuned for consistent operations.

Naturally, there are 3001 other reasons why thermostats are needed in both gas and diesel engines! But, reasons to remove one? Hmmm , nope don't know any of those!

jb

 

[MJPetersen]

Any chance your yanmar was thermosyphon?

i know the 1700 is.. and can accept the pump from a 2000 as a conversion...

Soundguy

Nope that is DEFINITELY a water pump. But it is curious as the Hoye parts manual does not show a thermostat anywhere. Guess some rumors are right. I wonder how they planned on getting the thing to normal temp in the winter? cover the rad I suppose, but they you need a gauge so that you know when it is time to open it a bit.

Hoye has a sale on the pumps right now for $116.
Mike

 

[dynasim]

<to slow coolant down so that it spends enough time in radiator to effectively transfer liquid heat to air>

is not valid. The amount of heat removed by the air passing through the radiator is directly related to the temperature of the water in the radiator. If you slow down the flow in the radiator, you will decrease the temperature in the radiator, and you will remove less heat.

If GM taught this concept, they had poor engineers. I can believe that.

There may be reasons to keep constrictions (open thermostats) in the line. Primarily, the pump was designed with that restriction. The reason is just not this one.

Chris

 

[3RRL]

The amount of heat removed by the air passing through the radiator is directly related to the temperature of the water in the radiator.
Ok, I agree with that.

If you slow down the flow in the radiator, you will decrease the temperature in the radiator, ...
So slowing down the flow in the radiator decreases temperature in the radiator. Yes, I agree with that too, but why? It's because it has time to dissipate the heat more effectively. That is THE big reason to leave your diesel idle for several minutes before shutting down. Especially on turbo charged units.

... and you will remove less heat.
Because there is less heat to remove because of the above.

In otherwords, what you said was "not valid" (<to slow coolant down so that it spends enough time in radiator to effectively transfer liquid heat to air>) is indeed a valid statement IMHO.

 

[SPYDERLK]

Quote 3RRL: So slowing down the flow in the radiator decreases temperature in the radiator. Yes, I agree with that too, but why? It's because it has time to dissipate the heat more effectively. That is THE big reason to leave your diesel idle for several minutes before shutting down. Especially on turbo charged units. " "

So youre describing cooling less water more. This is not necessarily better than cooling more water less. Faster flow increases turbulence which aids heat transfer. Admittedly, the water would not cool quite as much during its quick pass thru the radiator but it would be passing thru more often and would more than make up for it. The "not enuf time to transfer heat effectively" is an attempt to explain what has been seen when removing thermostats and seeing a detriment. Its not a correct explanation because it does not obey physical laws governing heat flow. I suspect what really explains it is that bubbles form in the coolant under flow conditions that are caused when the thermostat is removed.

The reason for idling before shutdown is not as much related to this as it is to reducing the amount of heat being produced. It lets the hot spots cool gently while the cooling system and oil continues to distribute and remove the heat.
larry

 

[skipmarcy]

Quote 3RRL: So slowing down the flow in the radiator decreases temperature in the radiator. Yes, I agree with that too, but why? It's because it has time to dissipate the heat more effectively. That is THE big reason to leave your diesel idle for several minutes before shutting down. Especially on turbo charged units. " "

So youre describing cooling less water more. This is not necessarily better than cooling more water less. Faster flow increases turbulence which aids heat transfer. Admittedly, the water would not cool quite as much during its quick pass thru the radiator but it would be passing thru more often and would more than make up for it. The "not enuf time to transfer heat effectively" is an attempt to explain what has been seen when removing thermostats and seeing a detriment. Its not a correct explanation because it does not obey physical laws governing heat flow. I suspect what really explains it is that bubbles form in the coolant under flow conditions that are caused when the thermostat is removed.

The reason for idling before shutdown is not as much related to this as it is to reducing the amount of heat being produced. It lets the hot spots cool gently while the cooling system and oil continues to distribute and remove the heat.
larry

There is no air to form bubbles in a properly filled, closed cooling system. Heat transfer from the coolant to the metal surface of the tube in the radiator - the longer it stays in contact with this cooler surface, the more heat is transfered away from the coolant. Same thing with the heat transfer from the iron cylinder wall to the coolant. Pour a cup of water in a hot skillet for 5 seconds or for 15 seconds - which one will produce hotter water? It's pretty basic. In the case of removing a thermostat in an engine, some systems can handle it better than others, depending on alot of factors, but in most automotive engines you will definitely see some sort of increase in operating temp. at higher rpms, some to the point of overheating especially if the radiator isn't 100% clean or a soft lower hose trying to suck shut etc. etc. It's still a good idea to gut a bad thermostat as opposed to removing it completely to get you by until a replacement can be installed.

 

[Tom_Veatch]

"It said none of the overseas models have them, only U.S. models."
No one addressed this aspect of the question. Is this part true?

Mike

No, it is not true. The YM2220, which is definitely a Japanese rather than an U.S. model, does have a thermostat. Or at least the one I own does.

(And as other's have indicated, physics is no respector of national origin. Physical principles are the same regardless of the language printed on the warning decals.)

 

[Egon]

Lets consider boundary layers, rate of heat transfer for ambient conditions, laminar or turbulent fluid flow and its impact on rate of heat transfer to fluid mass per given unit of time!