Temp gauge not working

[mck]

Ok, So I set up my Aux fan to the E30 switch I wired the relay to the black/brown wire so it turns on at the lower temp. But I ran the car to check if the fan turns on and it ran for about 5-8 min and the dash temp gauge did not go past the start of the blue section of the gauge. Also the fan never turned on.
It was a fairly warm day, so the temp should have gone up a bit more.

How can I check if the switch is working?
I soldered the wires on, could this have messed up(overheated) the switch?

[e30this]

you need to change the coolant gauge sensor on the side of the head to one from an M20. The one from the M20 is a brown top and the one that you change on the side of the head is the second one from the front.

[Kerrath]

Which switch? The one in the rad or the A/C Switch? I don't see how you could have overheated it unless you were using a blowtorch half an inch from it. Double checked your wiring?

As for testing to see if it works... I've been wondering about that myself, and I think your best bet might be to get a spare one, plug it in and dunk it into a pot of boiling water. I assume just heating it with a torch would work too.

Early model or late?

M5xs take forever to get warm btw.

[Kerrath]

you need to change the coolant gauge sensor on the side of the head to one from an M20. The one from the M20 is a brown top and the one that you change on the side of the head is the second one from the front.

I just did this. IIRC it's black. It's the 1 pin one for the E30 sensor and the black one in the m50 is 2 pin, but it's plug'n'play. You'll need a 19mm deep socket. I tried going at it with wrenches but without taking the intake manifold off that's a no-go. Disregard my comment about checking wiring.

[mck]

I used the radiator out of a 89 318i.
And its a euro S50B30 if that makes a diffrence.

[mck]

Thanks heap for that.
I used the temp switch from the m40 motor and it works perfect.