Warm Up Regulator 1982 924 Question

[996c4s]

Anyone familiar with WURs in general? I removed mine from my 1982 924 and it seems to be the wrong part number... also and hence my question... it seems to have a 2nd circuit in it. I will attach a photo if I can.

Questions would be... there is a set screw in the 2nd circuit... what should it be set at (contacts touching or circuit open when cold)? Next... should I replace it or is it possible to use it now that its rebuilt? Of course I need to know the answer to the first question of course.

The photo is horrible but it I did circle the area I am talking about. I believe the part number on the unit is 0438140088... which sees to indicate it was designed for Rolls Royce application according to "specialauto.com"

Anyone have any insight? Thanks
Eric
Eturbo924@yahoo.com

[996c4s]

Oh and it does not look that awful anymore. I cleaned it all up.

[Monkey Wrench]

not familiar with 924's but it appears to be a switch, is it inside the water jacket?.

ayway just general info ; often thermal switches incorporate a bimetallic strip. If you bond two different metals together the resulting strip of metal will bend at different temperatures in a predetermined way since the expansion rates of the two metals are different.

often with a thermal switch, it will have contacts which open and close based upon the bending of the bimetallic strip. If the strip is corroded or bent it might change the adjustment. the contacts might get dirty .

likely if you could put this in a pot of water with a thermometer you could adjust it to open or close at the specific temperature desired. ( with a meter measuring conductivity to see at what temperature the contact points are open or closed)

is it possible to put that switch in a pot of water on the stove to check it out?

[996c4s]

Yes I could put it in hot water to see. I did connect it to 12 volts and observed the bimetallic strip moving. When the circuit open it takes maybe 10 minutes to make the strip heat up enough to move. With the circuit closed it moves much faster. Maybe 2 to 3 minutes and it move. So I guess it depends on how long I want the cold start pressure to remain. I just dont know where that circuit should be set. Currently I adjusted the screw so the contacts just touch. But I did not observe it opening even after I let it heat up.

[Monkey Wrench]

you cna use a 9V batter and a car light bulb , or a meter to check when it closes and adjusting may affect opening and closing temp. The duration , Im not sure.

light bulb flashers are similar but the element may be heated by resistance so in that case changing the resistance can change the open time, an example is a person making their car lights flash at the wrong speed by using the wrong bulbs or adding a trailer to the circuit. that arrangement uses a bimetallic strip too.

if there is resistance through it, then there is a voltage drop and there is heat generated. a motor overload may use the principle, If the motor goes into a locked rotor state, it uses a huge amount of current, then the bimetallic strip may open, and when it cools the motor starts again. That can create an unexpected startup so many motors use a circuit that unlatches and requires the press of a start button to initiate movement. You might see those for example on an air handling fan, and a Hvac tech would know that if it's blown, It may or may not have a red reset button.. some can reset itself and start with no warning. motor like that would be a bad choice on a tablesaw, as it could cause injury.

with that I think it is just dependent on the water temperature if it is normally immersed. it looks like a waterpump housing but I can't really place where it goes exactly. maybe it activates an engine fan or idle air valve or something similar? it seems to be there to turn something on and off based upon water temp.

a lot of cars have a thing that looks like a plug with pipe threads that screws into the block or the head, it may run the temperature gauge in which case the gauge needs to see some voltage variation. Some switches like that are on or off with no variation. to turn on a check engine warning lamp or the rad fan, for example.

I suspect this one you are looking at has no heat element and nothing to do with the circuit resistance, It is simply moved by water temp and it's only function is to open or close a set of contacts. you might compare that to an old style thermostat in a house, it has a coil that moves dependent on heat ( in the room) and a bulb filled with mercury , when the mercury shifts it makes and breaks the contact. That's very reliable, it wont spark, nothing to wear out. The problem is, mercury is sort of a banned substance now. many modern ones are electronic programmable gizmos