Jiggle valve?

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What specifically is a jiggle valve as it relates to a thermostat? Specifically, how it relates to a ford 3.0 vulcan. The shop manual says position the jiggle valve in a certain position, but it does
not define what it is. Can someone enlighten me on this?
Also, can a thermostat be put in wrong if its not at a certain orientation? What are the symptoms if its in wrong?
Short story, last fall i changed out the radiator, water pump and thermostat in my 93 taurus 3.0. (radiator was leaking) The car runs fine, but the temp gauge on the dash slowly climbs to 3/4 of the way, then jumps down to about 1/4 of the way on occasion. Its not missing when it goes up 3/4. Its not in the red and below the edge of the hot mark.
I think i did not check for a jiggle valve orientation when i installed it last fall. that's why i am asking. I also wonder if the first speed of the two speed radiator fan is out if it could cause this problem.
The other thing i noticed was the OEM ford thermostat had a small hole in the plunger. The replacement did not. Does this little pressure EQ hole (or what ever it is) affect operation? What's its purpose?
Bob
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In the OEM thermostat there is a little valve that lets any trapped escape. A lot of aftermarket replacements won't have it.
(remove)sound wrote:

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I drill an 1/8 in. hole in all my thermostat's to let the air bleed out. Never had a problem with overheating. That maybe what the hole in the original thermostat was for, air bleed.

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On Wed, 11 Feb 2004 05:05:52 GMT, "Sans Nom"

No, that hole is there so that there will be a small amount of coolant circulation past the thermostat's actuating mechanism. If it wasn't there to allow that circulation, how would the thermostat sense a rise in coolant temperature? It would not open when it should.
Some thermostats don't close completely, and therfor don't need such a hole.
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"John Ings" wrote

This is incorrect...you need to research this more so that you don't lead unsuspecting and unknowledgable people that may be looking for information here....down the garden path.

What are you talking about? There are plenty of thermostats that both close completely and don't have any holes, jiggle valves...etc.
Now where do "you" think that the coolant circulation comes from on these vehicles? You should research this so that you will be able to make a more informed post about this subject the next time around.
Ian
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shiden_Kai wrote:

Dam Ian, you dangled the banana, then put it in the tail pipe? Care to enlighten me on thermostats? I used to think a thermostat was a thermostat. This is improper thinking. I am just trying to educate myself on this. The shop manuals assume you know this already.
Bob
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On Wed, 11 Feb 2004 18:17:43 -0600, BOB URZ

Try this
"If you're changing the thermostat at this time, keep in mind that all 'stats are not created equal, either. Carefully compare your replacement to the original one. If you're not using the exact original replacement part, the replacement part you have should exactly resemble the original, especially in the number of "stages" it has (one or twocheck the center area) and other features like a "jiggle valve." This valve is essential for quicker and more thorough initial filling of the system. Its absence will be replaced by your grief during the run-in procedure."
from <http://www.advanceautoparts.com/howtos_tips/automedia_html/ccr/ccr20030201rf/index.html?page=/howtos_tips/automedia_html/ccr/ccr20030201rf/ccr20030201rf.htm
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"John Ings" quoted:

But you originally claimed that the:

So which is it? The jiggle valve/hole is for a) quicker and more thorough initial filling of the system (ie: bleeds air from system easier).....or b) coolant circulation past the thermostat's actuating mechanism so that the thermostat can accurately sense the rise in coolant temperature?
Ian
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On Thu, 12 Feb 2004 06:40:11 GMT, "shiden_Kai"

Obviously a) is what the jiggle valve is for. So maybe the ones with a hole are for either purpose.
See my other post.
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On Wed, 11 Feb 2004 23:30:56 GMT, "shiden_Kai"

From the block on which the thermostat housing is mounted. Thermostats in that location have no problems sensing coolant temperature and don't need a hole.
But other thermostats are meant for vehicles that mount their thermostats in locations where there is not so much heat transfer from the block and where coolant circulation during warmup is primarily through a bypass and through the cabin heater core. Those thermostats need to pass some coolant in order to sense temperature properly. It depends where the hoses leading to the heater and bypass system are taken off, whether the intake manifold has a water jacket or is heated by a heat riser etc.
If you observe some engine layouts you'll see that the designers have fitted long snakey hoses from the car's heater to the water pump outlet near the thermostat housing. That means a lot of heat is lost in cold weather before the coolant ever reaches the poor frozen sod driving the thing, but hey, his thermostat is happy! On other cars there's a nice short hose from somewhere on the block close to the firewall. That makes for a warm, happy driver but a thermostat that is sort of out of the picture.

You too.
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"John Ings" wrote

Wow, John.....you need to either go back to automotive school or try to remember your basic automotive cooling system theory.
And if you have the time...please post a picture of a thermostat that is specifically designed to not close completely so that it can sense the temperature of the coolant in the engine. I've never seen one of these and am very interested in seeing how they work. Also the vehicle and engine that these are located in.
Ian
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On Thu, 12 Feb 2004 06:34:13 GMT, "shiden_Kai"

I suspect you are basing your arguments on current practices and haven't been around long enough to see some of the older stuff.

Nothing esoteric. They were usually the coiled element type with a hinged valve rather than the capsule element kind.

Well my experience was with Jaguars that had a water jacketed intake manifold. They also had a heater hose coming off the back of the engine with a valve in it that allowed the heater to be completely turned off in hot weather. The radiator bypass was so located that there was very little circulation of coolant past the thremostat. In my day water pumps bolted onto the front of the block, they weren't something you were advised to change when you replaced your timing belt because they were so hard to get at.
Now in the course of this thread I notice something I hadn't appreciated before, and that's this jiggle valve business. It's purpose is apparently to allow air to vent during filling but to stop coolant circulation past the thermostat.
So you could reasonably argue that in some cases a cheap thermostat would have neither a hole nor a jiggle valve. A better one might have a hole, not for circulation but just for air venting, and an expensive one would have the extra complexity of a jiggle valve.
I'm only going by what I was taught many years ago. Who's to say it applies today?
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wrote:

My OEM Ford thermostats have jiggle valves. My Autozone Stant replacements did not. Didn't make any difference in my flush and fill efforts. One of the replacements was due to a "it never warms up" issue and I found that the old thermostat never quite closed all the way. It was *almost* closed but not quite. It made a huge difference in warm up time and, during colder weather, prevented it from ever reaching proper temp. Based on all that, even a 1/16" diameter opening (without a jiggle valve) in the thermostat is too much to allow proper operation during cold/mild weather. -- Elbridge Gerry, of Massachusetts:
"What, sir, is the use of militia? It is to prevent the establishment of a standing army, the bane of liberty. . . Whenever Government means to invade the rights and liberties of the people, they always attempt to destroy the militia, in order to raise a standing army upon its ruins." -- Debate, U.S. House of Representatives, August 17, 1789
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wrote:

Interesting.
Did you test it for proper opening temperature? Perhaps it was also opening too soon.

Um, I don't think that's taking all the factors into consideration

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wrote:

Yup. It didn't open all the way and it didn't close all the way.

Well, I really don't think Ford would have wasted the extra money it cost to put the little hole AND the jiggle valve to block it off if they thought the 1/16" hole without jiggle valve would be good enough. The obvious design was to allow air to get thru the hole but as soon as water reached it to block it off. So I remain of the belief that a 1/16 or larger hole would be detrimental to the operation of the thermostat.

-- Elbridge Gerry, of Massachusetts:
"What, sir, is the use of militia? It is to prevent the establishment of a standing army, the bane of liberty. . . Whenever Government means to invade the rights and liberties of the people, they always attempt to destroy the militia, in order to raise a standing army upon its ruins." -- Debate, U.S. House of Representatives, August 17, 1789
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wrote:

But did it open too soon? At too low a temperature?

Yet you stated "My OEM Ford thermostats have jiggle valves. My Autozone Stant replacements did not. Didn't make any difference in my flush and fill efforts." So what's it for?

How the heck much flow could you get through a 1/16 in hole?
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"AZGuy" wrote

Yeah, very few of the GM thermostats have either jiggle valves or holes in the thermostats. The engines either have bleed valves in a few locations around the engine to aid in bleeding the system, or the engine cooling system is designed to self bleed easily. The Northstar engine comes to mind as an engine that self bleeds quickly and easily, you just pour in the coolant and run it....and it will self bleed. The late model 2.2 (OHV) engine is almost impossible to bleed unless you use the bleed valve sitting on one of the heater pipes.
The fact is, thermostats aren't supposed to be open at all in the warm up stage. That's why engines have bypass hoses or circuits, so that the coolant is circulating through the block and heads until it warms up to the point where it will activate the thermostat (which has it's temp sensing pellet sticking right into that "bypassed and circulating" coolant. Having coolant go by a thermostat by it being partially open will simply mean that the engine won't heat up as quickly and will never achieve it's intended temperature.
Ian
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If you look real close you will find a small triangle cut out of the edge of many t-stats. Probably not the ones with "jiggle" valves though.
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And the D-shaped flapper valve of the old coil actuated kind used to have a small amount clipped of the end of the D
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On Wed, 11 Feb 2004 05:05:52 GMT, "Sans Nom"

the warm-up process
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