Why idle before shut off?

[tommaple]

WHODAT526 wrote: "i just have one more dump question if a farmall cub does not have a water pump, but is water cooled. would that be a exception to the rule or not? because it does have a thermostat does it hurt the motor to just shut it down before idling down."
"i am just curious how that motor cools the water is all i have never worked on one of the motors in a farmall and is curious to know"

The first tractor I was ever on was a Farmall Cub that my Dad had. That was back in the '50's so I don't remember the details on that particular machine. The next tractor was a John Deere B. The old two-cylinder John Deere's did not have a water pump. The water circulated by convection. The hot water rose from the engine to the radiator and cooled water flowed back to the engine through the lower hose or pipe. They had a gradual upward slope from the block to the radiator. The important thing was that they were designed to run without a water pump from the get-go. The pipes did not have dips and curls that would slow down that convection. Modern engines have all kinds of turns and dips in the hoses that make a pump necessary to move the coolant.

 

[Don87]

That is a great question! :anyone:

I would expect that convection circulation is in effect and the running state of the engine would be irrelevant other than to provide an oil bath to certain parts until they cooled sufficiently. I don't know if the engine temperatures get hot enough for this aspect of cooling or metalurgy to be critical though.

Keep talking, I'm learning..........as well as countless others.

 

[whodat526]

WHODAT526 wrote: "i just have one more dump question if a farmall cub does not have a water pump, but is water cooled. would that be a exception to the rule or not? because it does have a thermostat does it hurt the motor to just shut it down before idling down."
"i am just curious how that motor cools the water is all i have never worked on one of the motors in a farmall and is curious to know"

The old two-cylinder John Deere's did not have a water pump. The water circulated by convection. The hot water rose from the engine to the radiator and cooled water flowed back to the engine through the lower hose or pipe. They had a gradual upward slope from the block to the radiator. The important thing was that they were designed to run without a water pump from the get-go. The pipes did not have dips and curls that would slow down that convection. Modern engines have all kinds of turns and dips in the hoses that make a pump necessary to move the coolant.

but would they steadly get hotter and hotter the longer it ran just like when u shut down a engine that has a water pump that is what is am wondering i just cant figure out how they can run so long and not run hot i have ran one for hours at the time it has me puzzled because these tractors seem to contridict what was said in previous post and i dont know how it works but it does just how

 

[whodat526]

I personally have never worked on a cub, so I can't answer the question.
But I am looking to possibly buy one...........and after looking over the water circulation process, I'll be sure to post my findings here.

But since you told me about the 'no water pump'........I may have to rethink my ideas.

a farmall cub is a really good little tractor i like the yellow and white version the best u would be surprised at what they can do with only 11 to 13hp

 

[tommaple]

but would they steadly get hotter and hotter the longer it ran just like when u shut down a engine that has a water pump that is what is am wondering i just cant figure out how they can run so long and not run hot i have ran one for hours at the time it has me puzzled because these tractors seem to contridict what was said in previous post and i dont know how it works but it does just how

The water pump in a modern engine is, in itself, an obstruction to convective flow of coolant. The old non-waterpump engines had no obstructions to hinder the flow of coolant.

 

[whodat526]

The water pump in a modern engine is, in itself, an obstruction to convective flow of coolant. The old non-waterpump engines had no obstructions to hinder the flow of coolant.

then what is the use of the water pump other than another part to break and cause major problems

 

[johnrex62]

then what is the use of the water pump other than another part to break and cause major problems

I think the answer to that is to further regulate water flow. A too cool engine does not operate well and restricting water flow will speed the warm up cycle for the engine. Once the engine has reached operating temperature, water can be forced in to maintain that temp more effectively with a pump than by relying on convection.

There are trade offs to this process, in both cost and reliability, but it makes operating the machines more convenient.


This lesson was courtesy of my uncle who ran a garage when I was a child, and is only pertinent when the engine is equipped with a thermostat. Convection cooled engines will not have one, but I would expect all modern, pump equipped engines to.

 

[tommaple]

then what is the use of the water pump other than another part to break and cause major problems

The older engines were not as high performance as newer engines. They did not produce as much horsepower per cubic inch of displacement as current engines do. To obtain higher performance, greater efficiency and now, to meet emission standards, an engine has to run at a higher temperature. Natural convection is not sufficient to cool an engine with higher operating temperatures and tighter manufacturing tolerances. More gallons per minute are needed, hence a pump to assist the flow of coolant.

If you look at the oldest stationary, horizontal, single cylinder engines, they did not even have a radiator. They ran so slow and developed so little heat that they were cooled by putting water in a cavity on the top of the engine.

The old John Deeres were slow running too. That's why they had such a large (by today's standards) flywheel. The flywheel kept the engine turning from power stroke to power stroke. That's how they got the name "Poppin' Johnnies". They ran so slow you could hear each cylinder fire individually. They sounded as if they were ready to stall, but the inertia of that large flywheel kept them going.

That's all for tonight, I'm going to bed.

 

[whodat526]

I think the answer to that is to further regulate water flow. A too cool engine does not operate well and restricting water flow will speed the warm up cycle for the engine. Once the engine has reached operating temperature, water can be forced in to maintain that temp more effectively with a pump than by relying on convection.

.

i thought the thremostat was for restricting the water flow till it warmed to a certian temp then the thremostat opened until cool water hit it then it closed and the water pump was to pump water not slow it down.
i might have read ur post wrong

 

[whodat526]

The older engines were not as high performance as newer engines. They did not produce as much horsepower per cubic inch of displacement as current engines do. To obtain higher performance, greater efficiency and now, to meet emission standards, an engine has to run at a higher temperature. Natural convection is not sufficient to cool an engine with higher operating temperatures and tighter manufacturing tolerances. More gallons per minute are needed, hence a pump to assist the flow of coolant.

If you look at the oldest stationary, horizontal, single cylinder engines, they did not even have a radiator. They ran so slow and developed so little heat that they were cooled by putting water in a cavity on the top of the engine.

The old John Deeres were slow running too. That's why they had such a large (by today's standards) flywheel. The flywheel kept the engine turning from power stroke to power stroke. That's how they got the name "Poppin' Johnnies". They ran so slow you could hear each cylinder fire individually. They sounded as if they were ready to stall, but the inertia of that large flywheel kept them going.

That's all for tonight, I'm going to bed.

but a cub dont have a big flywheel and run just as hot as a engine made in the 80s-90s before the major emisions changes i believe