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No Heat At Idle Air Lock


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There has been a lot of talk on this, and while reading up on it I found this:

Insert the thermostat into the water inlet housing with the jiggle valve facing straight upward.

Now I have been in auto mechanics all my life, and this was new to me... maybe in Texas we are behind. Then I read up on the "jiggle valve" and found it to be an "air bleeder"

This made me think, if you installed it with the valve DOWN, would that prevent getting the air out of the system, and thus a constant "air lock" ??

I am searching for answers.... what about it, landar, kansas, pd, curious, vb, steve, have you guys always known about this, and I am just finding out???

looking for a little knowledge...

86713057L.bmp

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while researching, I found this:

The valve allows trapped air to escape when the cooling system is flushed or broken open and drained. The trapped air is a serious problem creating hot spots and erratic sensor behavior. There are reports that the air is hard to remove without the valve. Since air seeks vertical height in water,

comments????

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I know that if you install the thermostat backwards in an engine, the engine may overheat. Done that on a Ford(once).

As pertains to the jiggle value or air hole, these are used to allow air that is initially trapped around the thermostat to move through. So, when you first drain/fill a coolant system, you do not want an air pocket right up against the thermostat or it may not open properly at first, allowing hot spots in the engine block. And you always want a small amount of coolant flowing past the thermostat even when the engine is cold. The valve or vent hole accomplishes this(some replacement thermostats do not have the jiggle valve). I do not believe the valve would be the cause of not being able to purge air from the entire system however. If the thermostat is opening properly,once the engine is warm, there is plenty of area for air to come through.

Having said this, owners experiencing air lock symptoms might want to replace their thermostats as cheap insurance(ensurance of proper operation?).

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I am having a similar problem. I have burped the system a couple of times to no avail. The coolant level is fine and I just drove about a 1000 mile trip. My system will go cold at idle but only needs maybe 1200-1500 rpm to get warm. The heater control valve works fine and there are no leaks. I have not changed the thermostat but plan on doing so even though that seems an unlikely suspect. One curious symptom is that i can put the car in park and rev the engine and the heat will stay warm at 600 rpm until I move the car again. Could this be a ECU problem?

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Could this be a ECU problem?

I do not see how this could be the ECU, I would lean more towards a partially "clogged" heater core, or the (as you said) thermostat, the stat is an easy fix, so try that first. good luck and keep us posted.

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I've seen the jiggle valve but never knew that was what it was called. Strange name.

Its purpose make a lot of sense though. If the space under the thermostat gets trapped with air then the thermal plug of the thermostat won't touch coolant and as a result may never heat up enough to open up the thermostat (or at least delay the heating and opening). This could cause the block to overheat. Ouch. I wonder if it has a secondary purpose to let a small amount of fluid through in the event the thermostat gets stuck in the closed position as a failsafe feature? Not sure if enough leaks through to provide any meaningful cooling. I think thermostats typically fail to open though so perhaps a moot point.

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A lot of the German thermostats use them - Volvo and Mercedes, at least the older ones I used to work on. Usually referred to as a "jiggle pin" and is used to bleed air through a closed ( when installed ) thermostat. Volvo specified the pin to be at 12 o'clock, and Mercedes the same. Infrequent coolant changes normally plug it up as the passage is so small.

I used to drill Chevy and Ford thermos in the outer disc - a 1/8 inch hole - and that sure helped with filling.

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So, I changed the thermostat this afternoon and before doing so had drained about a half gallon or so of fluid. After replacing the thermostat, which looked in good condition except the jiggle valve was at 3:00, I refilled and burped the system. It took more than the half gallon I drained, about 3/4 of a gallon , and the heater now works as advertised. I had tried the burp procedure twice already but there must have been some massive air bubble in the system to take more coolant than I drained out. Thanks for the thread.

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So, I changed the thermostat this afternoon and before doing so had drained about a half gallon or so of fluid. After replacing the thermostat, which looked in good condition except the jiggle valve was at 3:00, I refilled and burped the system. It took more than the half gallon I drained, about 3/4 of a gallon , and the heater now works as advertised. I had tried the burp procedure twice already but there must have been some massive air bubble in the system to take more coolant than I drained out. Thanks for the thread.

That is interesting, ljgiles. It sounds like you finally displaced the air with another 1/4 gal of coolant, which is quite significant. Did you put the new TS in with the jiggle @ 12 o'clock?

Billy, it was a good idea to start another thread with this topic as so many have this issue. Should be a sticky!

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