coolant flow - (follow up to cooling diagram)

[widdowson2008]

....
conclusion imho is that the jiggle pin is actually a float and only opperates properly when in contact with water ??????

ady

Sorry but I don't think so. It's solid steel, not a hollow float construction. The only way it can block the hole would be if there were a swift flow of coolant going past it, and even then I don't think it likely. ....but I could be wrong

Just tried it in water to be sure and it doesn't float. Had to make sure though cos stranger things happened on a Bongo.

[dandywarhol]

The jiggle pin should float, in other words, it should sit against the stat flange and keep coolant from transfering to the upper part of the stat.

My reckoning of the stat needing to be open when bleeding air out is to make sure there's no air ANYWHERE in the system because there's nowhere for it to hide when everything is flowing

[maxheadroom]

Quote taken from Pistonheads food for thought


blitzracing said:
We have problems on the Ginetta's (RV8)with the temparature fluctuating between 85-95'. Im told this is due to steam pockets developing in the top of the head, that does not cause the thermostat to open untill the cooler water lower down gets warm enough to open the stat itself. The cure is to drill a 4-6mm hole in the very top of the 'stat to allow any steam to escape, so the water level on the stat is always as high as possible. Dont know if this is technically correct, but it solves the problem for sure. It may just be a problem on the Ginettas as the header tank is only just above the heads.
I like the drilling holes idea .. I only drill a 3mm hole in the top of the RV8 stats though on road cars because if you go too big you cna run into overcooling in winter, it's surprising how little coolant flow is required to keep an engine temp down in winter on light cruise, also the hole provides an air-lock escape route to aid filling the system and also (i think) gives a more progressive first opening of the stat as you're bleding through warm water before the true stat operating temp is reached, so you eliminate the hot/cold/hot swing.
Good point Trackcar,have been modding stats like this for years,works wonders for the Rover K series,that can be a bugger to bleed,your def right about that hole size 3mm seems a ideal compromisethumbup

http://wiki.seloc.org/a/Pressure_Relief ... Thermostat

http://www.pistonheads.com/gassing/topi ... 0&t=473074

[mikexgough]

We kind of covered the K series when doing the "how it works" bit when discussing the Bypass part of the cooling system.

I had seen that post on Pistonheads before and I guess that gives another slant on things from a performance perspective and is a valid point to raise.

I think ( put up against the wall if I am wrong).. Widdowson is looking at the principles of the "base" Mazda System with O.E parts and on the basis that the O.E system is sound and needs no modifications.

[widdowson2008]

The jiggle pin should float, in other words, it should sit against the stat flange and keep coolant from transfering to the upper part of the stat.

My reckoning of the stat needing to be open when bleeding air out is to make sure there's no air ANYWHERE in the system because there's nowhere for it to hide when everything is flowing

Hi Alan
Tried again and I can't get the jiggle pin to float. This is on a new, genuine Mazda stat. So a bit baffled by this one.

As you know, the stat housing fits to the engine at a slight angle. The 'ear' on the seal positions the jiggle pin at the highest point ie: where air is going to collect. This would release trapped air in the pipe between rad (bottom) and stat housing.

[dave_aber]

Is it not the case that the jiggle pin doesn't float, but will hang down open in an air pocket, and be pushed closed by a water flow, and as such acts as a auto-bleed valve for the stat housing?

[widdowson2008]

Is it not the case that the jiggle pin doesn't float, but will hang down open in an air pocket, and be pushed closed by a water flow, and as such acts as a auto-bleed valve for the stat housing?

Thats the way its looking to me. Still cant get it to float

[maxheadroom]

http://wiki.answers.com/Q/What_is_the_f ... thermostat

Most thermostats have a Jiggle pin. Its function is to allow trapped air past a closed thermostat as a build up of air in front of the wax capsule could cause engine damage. The wax capsule relies on coolant to relay heat to operate. If air was surrounding the capsule and the engine was at operating temperature, the stat would remain closed and cause the engine to overheat.

and the beat goes on

[widdowson2008]

http://wiki.answers.com/Q/What_is_the_f ... thermostat

Most thermostats have a Jiggle pin. Its function is to allow trapped air past a closed thermostat as a build up of air in front of the wax capsule could cause engine damage. The wax capsule relies on coolant to relay heat to operate. If air was surrounding the capsule and the engine was at operating temperature, the stat would remain closed and cause the engine to overheat.

and the beat goes on

Thats a direct quote from Tama Thermostats. For that quote, and other interesting stuff on stats, have a look at this http://www.tama-e.co.jp/en/faq.html
Jap spelling is a bit dodgy though:lol:

[maxheadroom]

thermostats with jiggle pin valves are equipped with a special valve in the flange,which allows trapped air in the system to escape and permits the venting of air from the system when filling it with coolant

http://www.gates.com/europe/brochure.cf ... on_id=5162

[widdowson2008]

thermostats with jiggle pin valves are equipped with a special valve in the flange,which allows trapped air in the system to escape and permits the venting of air from the system when filling it with coolant

http://www.gates.com/europe/brochure.cf ... on_id=5162

Spot on Max . Surprising how much info on stats is out there. If nothing else comes out of this, folk will at least have learned how a stat works. I know I have.

[missfixit70]

http://wiki.answers.com/Q/What_is_the_f ... thermostat

Most thermostats have a Jiggle pin. Its function is to allow trapped air past a closed thermostat as a build up of air in front of the wax capsule could cause engine damage. The wax capsule relies on coolant to relay heat to operate. If air was surrounding the capsule and the engine was at operating temperature, the stat would remain closed and cause the engine to overheat.

and the beat goes on

Thats a direct quote from Tama Thermostats. For that quote, and other interesting stuff on stats, have a look at this http://www.tama-e.co.jp/en/faq.html
Jap spelling is a bit dodgy though:lol:

But the air around the wax capsule theory doesn't work with the bongo's system.

[widdowson2008]

But the air around the wax capsule theory doesn't work with the bongo's system.

Very true. I think folk are mixing the Bongo system with a conventional one, and as a consequence, a load of totally irrelevant stuff is being spouted. There is enough confusion without adding to it.
How can we clarify this? C'mon, one last effort.

[mikeonb4c]

http://wiki.answers.com/Q/What_is_the_f ... thermostat

Most thermostats have a Jiggle pin. Its function is to allow trapped air past a closed thermostat as a build up of air in front of the wax capsule could cause engine damage. The wax capsule relies on coolant to relay heat to operate. If air was surrounding the capsule and the engine was at operating temperature, [THERE IS A RISK THAT]the stat would remain closed and cause the engine to overheat.

and the beat goes on

Thats a direct quote from Tama Thermostats. For that quote, and other interesting stuff on stats, have a look at this http://www.tama-e.co.jp/en/faq.html
Jap spelling is a bit dodgy though:lol:

But the air around the wax capsule theory doesn't work with the bongo's system.

Funnily enough I happened across that same quote when googling for jiggle pins this morning. I think whoever wrote it has just written carelessly and / or a bit presumptiosly. I think I might accept the statement if the bit I've inserted in red uppercase had been included in it. But unless he's been in one of those incredible shrinking things that allowed him to travel around the system and stop next to the thermostat and watch what happened, I'm left wondering how he can be quite certain.

When I googled jiggle pins I thought I noticed a few pieces suggesting it was there to both allow air to pass through and to allow a small amount of coolant to pass to either side of the thermostat so as to reduce thermal stress across it. No idea if that is the case, but I suppose expanding coolant on the hot side could pass through just as air does. Doncha wish you could get a thermostat designer to speak up and give us chapter and verse on it?

[mikexgough]

I don't think, being that the jiggle pin doesn't float, that we get too hung up over it and just accept that it is a means for allowing coolant through and to aid bleeding to a (pardon the pun) degree.