[h2pmr]

probably a pointless thread but am interested in the obscure things fitted to a 928 and how they work

fitted to the main washer bottle is a level sensor, i had a spare one from an 87 so thought i would test it on the bench.
multi meter set to ohms and got open circuit when connected to both of the terminals with the float in any location.
but when moving the float by hand can hear a very faint electrical click noise when the float roughly passes the half way mark, does it every time
i did try it in a cup of water and moved the float up and down with a small screwdriver and it did get continuity a couple of times but mostly still got nothing
so removed the float

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could see nothing so gently cut it in half and removed the bottom section of it.
metal shaft runs down the middle and connects to the "switch" which is connected to one terminal on the top.
red wire runs with it and connects to the other side of the "switch " which is connected to the other top terminal

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float itself is a light as a feather but must have tiny magnets in it.
even now if i run the float over the "switch" it still makes the faint electrical click every time.
is it a type of mercury switch ?
cheers
Phil

[smiffypr]

It's called a reed switch. Two contacts lightly sprung to normally stay apart but in the presence of a magnetic field they pull together and make contact. Usually very reliable.

[hans14914]

Yep, its a standard hermetically sealed reed switch.

I am actually in the process of making a replacement switch so I can use that threaded bung in the bottom of the tank as a -10ORB port as well to convert that tank into an intercooler fluid reservoir.

PIC had some nice switches as floats that fit well inside a A2024 seamless extruded tube. Have it working on the bench, but need to find a good shop to do the machining on the tube since that is a bit of a strange process.

https://www.pic-gmbh.com/en/

[h2pmr]

thanks Gents, if i find why it seems to be switching but not registering at the terminals i will let all know.
cheers
Phil