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E30 M3 aluminum radiator - wiring question

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    E30 M3 aluminum radiator - wiring question

    ​Hey Guys, after 20 years of collecting vintage BMWs and restoring them, I finnaly bought the missing link; an E30 M3 :) The car has some minor issues that I'm curently trying to sort out as I learn my way around the S14 which is quite different to the inline 6 I'm used to...! So I would love to get your feedback on a few things.

    I noted two issues that will need immediate attention.
    1) The oil temp gauge goes to maximum after a minute of idling and the car starts to idle more roughly by then, which feels like missfires or fuel starvation. I did some research and ordered a replacement oil temp sensor which I'll replace this week.
    2) The atmospheric pressure sensor is litteraly not there, so I assume this might contribute to the rough idle, combined with other factors...Altought I know that at sea level, the car can run fine without it too...

    That's said, on the other side of the engine (passenger side) just behind the headlight plastic cover, an amateur did some damage... There's a black 3 wire plug that was hacked into. There is one single wire that was soldered on to this plug and it goes down along the engine block. At the moment it's hard to see where it connects to... But it goes near the thermostat housing from what I can see. More details to come...I suspect a couple things... Maybe the new aluminum rad is missing a temprature sensor and this plug was disconnected, but connected elsewhere to potentially cancel a CEL or something... I also noted what looks like a temperature probe on the t-stat housing behind the radiator with both wires coming out of it cut. There is a blue connector beside the black 3 wire connector that doesn't seem to be used... this is potentially the one that connected to this temp probe...I'm not sure. Those are all things that needs to be confirmed. (see photos)

    Anyone has information on aluminum rad install that could point me in the right direction? Does the proceedure state that we need to disconnect or move wires around ?

    Thanks !

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    Last edited by lockeed; 06-09-2025, 03:17 PM.

    #2
    The bottom pic is the aux fan switch. If it's disconnected and the fan works, you know they bypassed it. The top pic is probably AC related.
    "I'd probably take the E30 M3 in this case just because I love that little car, and how tanky that inline 6 is." - thecj

    85 323i M TECH 1 S52 - ALPINEWEISS/SCHWARZE
    88 M3 - LACHSSILBER/SCHWARZE
    89 M3 - ALPINEWEISS II/M TECH CLOTH-ALCANTARA
    91 M TECHNIC CABRIO TURBO - MACAOBLAU/M TECH CLOTH-LEATHER

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      #3
      It's possible that this black 3 wire plug is related to AC, I'll need to dig around... This wouldn't cause the rough idle after 30 seconds though...

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        #4
        This is the black plug with one single wire thats seems to go down the the AC.
        The other picture is the 3 wire pigtail that was cut. If anyone know where these should connect to, that would help.
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          #5
          Pretty sure that's AC, like compressor clutch and whatnot.

          Aux fan wiring is on the other side of the car (like the connection to the fan).
          I don't know where the fan temperature switch is on the m3, but it could be this wiring.
          Try to find a copy of the ETM and check wiring colours.
          Originally posted by priapism
          My girl don't know shit, but she bakes a mean cupcake.
          Originally posted by shameson
          Usually it's best not to know how much money you have into your e30

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            #6
            I was able to get the car plated then drove it for a few runs and put fresh gaz in it . Good news, there is almost no fluctuations on idle now which is great. Initially, the engine would literaly cut off when passing 75% throttle, especially at higher rpm. (Like a sudden cutoff). I replaced all the temperature sensors as a precaution and also put new plugs in. I think I just needed to shake the cobwebs off as the car now pulls trough the rev band without hesitations. Still need to replace the oil temp sensor, other than that I need to figure out the wires on the passenger side and its not as bad as I initially thought. (head gasket)
            Last edited by lockeed; 06-13-2025, 01:10 PM.

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              #7


              I'll bet the appropriate year ETM will help...

              t
              now, sometimes I just mess with people. It's more entertaining that way. george graves

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