Classic cars forum & vehicle restoration.

Greeney in France · Posted: Fri Nov 21, 2008 8:37 am Post subject:

I think the jiggle pin is the little loose pin in the thermostat that allows air and a little water during the warming up process, usually has a little seating bobble on it. I was told by "experts" that if the thermostat doesn't have one to drill a little hole in the lip to help with venting
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peter scott · Joined: 18 Dec 2007 Posts: 7219 Location: Edinburgh

Jim Walker · Posted: Fri Nov 21, 2008 12:09 pm Post subject:

Sorry Peter - No. I can assure you that I picked up the name from a Manufacturers Diagram of the part to which it is fitted. So it must be genuine.
Incidentally, 'jiggling' the primer on (mostly motorbike) carbs really is a silly thing to do, as you say. I have come across many floats battered almost beyond recognition and even punctured by the practice. Much better to press the pin gently to feel the float position.

Jim.

Jim Walker · Posted: Fri Nov 21, 2008 12:19 pm Post subject:

Well that conundrum did not last long! While I was typing my previous reply several replies were listed.
The answer came across "La Manche" from Greeney.

Bravo! Jim.

Jim Walker · Posted: Fri Nov 21, 2008 12:27 pm Post subject:

By the way Greeney, I have always thought (and still do) that the hole prevents air being trapped below the thermostat when filling or re-filling the system. because trapped air would prevent the thermostat opening. Most (all?) cooling systems have restricted by-pass to allow some water past the 'stat during warming up.

Jim

Greeney in France · Posted: Fri Nov 21, 2008 7:40 pm Post subject:

Jim Walker · Posted: Sat Nov 22, 2008 12:48 am Post subject:

Greeney,
I cannot see how it relieves pressure. Pressure is the effect of temperature rise, not water pumping, and is relieved only when the vapour pressure of the system reaches the pre set value of the pressure (relief) cap. In fact, as you said, the Jiggle Pin has a ball end at the bottom, and that will be held off its seat by gravity with the engine stopped thereby allowing the air to escape on filling. When the engine is started and water starts to flow the pin will be pushed upwards and act as a one way valve preventing the passage of water. I believe the Jiggle pin is also intended to 'jiggle' while the thermostat is open to prevent the little hole clogging up.

That's a heck of a lot of typing for a tiny part!

Jim.

Greeney in France · Posted: Sat Nov 22, 2008 7:12 pm Post subject:

I think it was for reducing the cooling system pressures that develop in the engine before the thermostat opens not generally, it was my haste in writing that I failed to make myself clear
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the fly · Joined: 11 Jul 2008 Posts: 95

The device on float bowles used for flooding the carb has always been known to me as the tickler held down by large greasy thumb and not beaten up and down .Regards The Fly .

pigtin · Joined: 23 Nov 2007 Posts: 1879 Location: Herne Bay

The very fact that it is called a 'tickler,' probably encouraged people to jiggle it up and down. Laughing

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