Firstfives.org

Tom, you had responded on Oct 2 to the issues I was having with my e12-based 633 and I wanted to ask if you could elaborate concerning the plug with the 2 male spade connectors located at the bottom of the radiator. I haven't had time to trace the wires yet, but I called several parts sources, including the local bmw dealer here - no one can even find that part on the computer to tell me what it is or how much it costs. You mentioned it controlled the aux fan and was a temp sensor, but, with both those connectors unplugged, my temp gauge is workin fine and the aux fan is turning, don't know if it cycles off n on while I'm driving or not. Do I have some kind of wierd radiator from Guam or somewhere? I'm thinkin this radiator's the original, so wouldn't you think the dealer would show this plug? Do either of your 528's have this same radiator?

Thanks,

Bob

My 635 is a mix/match '78 633 with Alpina, euro toys and a euro 635 engine. Checking realoem.com, ( they keep fooling with it worse ) I see the part ( #15 on the radiator drawings ) but no parts list with numbers.

From the engine side, lower right corner of the radiator. Plug, sensor, looks like a fat spark plug base with two flat blade connectors. As with yours, one of the blades broke off.

I think Mike W. opined what it was and did about a year ago in a post. Temp and aux fan ? Air conditioner related, or the temp gauge on mine works.

My car is in bodywork limbo. Runs fine, but only around the block. Maybe the silly sensors are nla, or I'll have to look to see if they are the same as 528's.

Early E24s used an odd double switch for the two speed fan instead of two single ones like 528i's, so you probably have 4 wires hanging around down there. They were 91/106 IIRC, though maybe 99/106. Either way high speed was set to come on at too high a temp IMO. It will run with the A/C on regardless of the switch. I'd probably just put in a single 91, or you could get a 91/99 from an E30 but you'd have to get an E30 plug as it's 3 round terminals instead of 4 straight ones. And it's just a fan switch, no gauge function built in. On a side note, I think your E24 should have a warning light to go along with the gauge, it uses a double contact sensor with one actually being a switch, but it's up by the thermostat. But often those don't seem to work anymore.