thermostats

[tommays]

wild<br />the stat is normaly closed when cold and they are allways installed in a houseing that allows a low level of water flow to move through the block<br /><br />as the water flow warms up the stat starts to open to allow more flow based on the temp <br /><br />it can be anywere between its fully open and fully closed position and will move to a position based on the water temp that will try to allow only enough flow to bring the motor up to full temp<br /><br />the manifolds and risers allways get full water flow from the raw water pump the cir pump only moves water through the block passages<br /><br />if you fill the block from a high point the air is going to try to rise as the fluid takes its place and will gurgle out if <br /><br />tommays

 

[imported_wildcat]

thermostats

I am a newbie with a 5.0L 260 HP MPI with Alpha I. I need some help understanding thermostat operation.<br /><br />It is my understanding that when my 160F thermostat is closed, there is no flow at all. However, if the engine is not running and there is no water pressure, the thermostat is always open. <br /><br />I copied this statement from a related topic:<br /><br /> The air bleeds (jiggle pins) that were used on the thermostats of diesel engines in previous years are no longer used. They have been replaced by a vertically mounted one-way check valve (jiggle pin) and a rubber bypass hose. The check valve is used as as a servicing feature and will vent air when the system is being filled. It is also used to block the flow of coolant during engine operation (all coolant will pass through the thermostat).<br /> Water pressure (or flow) will Hold the pin closed.<br /> When the engine is off, the check valve will be in the open position. When the engine is operating the check valve will be in the closed position.<br /><br />My questions are:<br />1. If I remove the large hose from the thermostat and fill with AF, is the thermostat open or closed? I wonder how the block vents to allow it to fill with AF if the thermo is closed.<br /><br />2. During engine operation, the water pump is always operating off the belt. If the thermo is closed, there is no flow of water. What keeps pump from overheating if there is no flow?

 

[imported_wildcat]

Re: thermostats

Tommays,<br />Thanks for the help. <br /><br />It looks like your last statement was cutoff prematurely.<br /><br />"if you fill the block from a high point the air is going to try to rise as the fluid takes its place and will gurgle out if"<br /> <br />So the thermostat always allows enough flow when closed to fill the block with AF? <br /><br />The other question I had is if the thermo is closed and there is no water flow through the block, what keeps the circ pump from overheating since the belt is turning the circ pump with no water flow to cool it.

 

[Don S]

Re: thermostats

The thermostats have a vent hole in them, plus they are only a metal to metal seal and were never meant to stop a little leaking past it. They are installed to prevent the water from circulating too fast which doesn't allow proper heat transfer.<br /><br />The engine circ pump is not a pump like the raw water pump is. They will not build up any pressure due to their design, they will however circulate the water. They are also not dependent on water for cooling as you suggested. If there is air in the cooling system, it will stop the flow of water as surely as the thermostat will and it will cause an overheat. That is one reason a marine thermostat has a small hole in it so that air can bleed out of the block while filling with water or antifreeze and not get an air lock.

 

[tommays]

Re: thermostats

wild<br />thats were the small flow through comes in its allways moveing water around the block and a small amount is leaveing through the stat when its closed it has to flow some through the stat so the warm water starts to open it<br /><br /><br />the cir pump is not a positve displacement pump and will not be damaged as long as its got a water supply<br /><br />there should not be and (if) the air is going to try to go to the highest spot<br /><br />i have to say looking at your hose diagram its easy to see how it could be hard to winterize it looks like a submarine pipe maze and there are a lot of places to trap water<br /><br />tommays

 

[imported_wildcat]

Re: thermostats

You two are a wealth of information. It is very much appreciated. I cannot tell you how many people I talk to that cannot explain anything. I sure appreciate your patience.<br /><br />I hope you all have a great Thanksgiving. Just one holiday closer to going boating.