Thermostat question

[oldschool90]

So..... been thinkin for a while now, why is the jiggler valve there on a thermostat? wouldnt it be better if it was just a hole? It would prevent cold pockets of coolant from keeping thermostat closed and it would let air bubbles out. Whadya think? should I cut it off and see what happens? Or is there some major unknown purpose that would cause my engine to eventually fail if i did?

[Xander_42]

I don't know what the jiggler valve is (haven't actually had to look at a Datsun thermostat yet), but on the race cars I work on (which run motorcycle engines), we always run them with about a 1/8" hole in the thermostat, which does what you say, prevents air pockets and whatnot.

[oldschool90]

I don't know what the jiggler valve is

 

 

 

Here you go!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[oldschool90]

Hope that helps expand your smarticle particles

[Xander_42]

AAAAAAAA!!!!!!! MY SMARTICLE PARTICLES ARE SO BIG!:)

I see no reason you couldn't run without it, you know, except for the inevitable EXPLOSION!

Not real experienced with coolant systems, so not sure why I spoke up but, with my understanding of coolant systems I would say:

You should still be able to build pressure, maybe a little less in the engine, but the system will still pressurize. So it should work fine. I'd wait for an answer from somebody with more experience than me to answer though.

[MicroMachinery]

Air is going to get out whether the jiggler is in or not. I don't think that it's been installed in thermostats as an inefficient design. One plus side to having it is, by the chance that at some point your cooling system was ill maintained, and there are flakes of rust/gunk built up in your block, this will prevent larger chunks that could possibly lodge in your radiator and over time plug it up. The chunks will be forced to dissolve and become smaller particles that will easily pass through the core of your radiator. Just a thought, as I'm sure there are other perks to having the small jiggler there.

Don't worry about air not being able to get through. As long as there's some kind of hole there(jiggler or not), it will serve the same purpose. I doubt that there's enough air in your system to warrant cutting it off.

[datzenmike]

Why the little dingle dangle thing instead of an open hole??? I think that water pressure from the pump would flow through the hole and cause the dingle dangle to to act like a blockage. Water pressure would hold it against the hole and seal it.... after all it is called a jiggle valve. Any air bubbles will collect at the highest point in the motor against the thermostat. If the bubble is big enough to expose the jiggle valve the weight of the water against it would drop. the dingle dangle would drop back and let the air out. When the water tries to get out it would push the dingle back into place.

 

I'm going to say that any trapped air would expel the moment the thermostat opens. This would, of course, require you to recheck the rad level and top it up, but who doesn't anyway. So, if the air gets out when the thermostat opens then why have a jiggle valve in the first place???

 

Well I'm going out on a limb and propose that normally the jiggle valve isn't needed at all. Many thermostats don't have them, even replacement ones. So this leaves abnormal. What would happen if for some reason the thermostat stuck shut and the engine overheated, catastrophically overheated and the coolant in the block boiled to vapor? The steam bubbles would rise to the top or into the head and expose the water passages normally filled with coolant. The areas affected would get hotter and hotter as air does not have the mass of water to absorb heat. Now lets look at the jiggle valve. It opens and lets the steam bubbles out into the upper rad hose and water from the rad and lower areas of the block rise up and replace the bubble in the head and 'cool' it. well not cool ot completely, buy reduce the danger, perhaps long enough for the driver to realize there is something wrong.

 

Yes, at the same time if the pressure rises high enough, the rad cap will open and relieve the pressure of the boiling water, but without the jiggle valve to let the steam out it will expel vital coolant that is needed. With the jiggle valve, steam is allowed out the upper rad hose to the rad where it can be vented and what coolant is left stays in the system.

 

Jiggle valve or open hole doesn't matter that much, it's just a little boil over insurance from a failed thermostat. Well that's my take on the matter.

[oldschool90]

Ended up cutting it off. I'll let y'all know what happens. Hopefully not a BOOM