Topic: Unobtainable BMW Temperature Switch
For a non-lemons project I bought a 1987 BMW 528e (M20, 2.7L engine). This thing uses Motronic 1.0. There are no less than 3 separate systems to deal with the air/fuel for idle etc. But I digress.
I'm going through this thing pretty thoroughly. I'm on the front of the motor right now. Water pump, timing belt, cam, crank & intermediate seals, rocker cover and oil sump gaskets, etc. The thermostat housing is two pieces. The bigger of the two has 4 (FOUR!) temperature sensors: 1 for the main ecu, 1 for the gauge and 2 more for idle control.
Most replacement parts are readily available, for example the thermostat housing. Cheap and easy from URO and available through amazon, rockauto, etc. I start taking apart the thermostat housing that has all four sensors and the temperature switch falls apart as I start to take the leads off of it. It has two spade connectors on top. I don't think too much about this as I already bought the a replacement for the Bosch ubiquitous CLT sensor.
I get to the computer and look up the part number on RealOEM and start searching. Nothing. What I do find at some of the usual BMW parts sellers is that this part is NLA-no longer available. They used this part on a fairly wide range of cars in the 80s but no one seems to have any of them around.
Specifically, this is a 45*C, normally open temperature switch. I guess what makes it unique is the relatively low operating temp. 45*C is only 113*F. Kind of an oddball temperature for engine coolant. But like I said, the whole thing is oddball.
In any case, Ive posted on the e28 forums and there is at least one guy looking for a salvage part. My inquiries at the usual suspect BMW parts shops have turned up zero. I'm going to take a look at this thing and see if I can fix it. Solder new terminals? Seal it with silicon? Not sure. First I will test it to see if it even works.
I brought this issue here because of the various automotive forums I frequent, Lemons seems to have the best balance of ingenuity and resourcefulness. During all my Google-Foo on this subject I did find a link to a generic 45*C, NO temperature switch. Form factor is off and the thread is wrong but it could work, if it works. Since its a switch I don't believe there is too much it has to do to work.
Here are some pictures (the part in question is #15 in the diagram and carries BMW part # 12631279716):
Swedish Knievel Skycycle('90 Volvo 740 Wagon)