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Cooling your M30

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    Cooling your M30

    Cooling your M30!

    Good: Stock aux fan
    Better: 16” pusher fan mounted on the radiator (or condenser if running AC**)
    Best: 16” pusher fan mounted on the radiator (or condenser if running AC**) and 10” puller fan mounted just in front of the alternator.

    **Use a fan gasket between the condenser and radiator to direct airflow into the radiator instead of around it

    Fan switches/controllers
    Good: Stock m20 90/92C switch
    Better: OEM 80/88C switch, p/n 61 31 8 361 787
    Best: PWM fan controller (try

    Water Pump
    Good: Stock water pump
    Better: OEM “hot climate” overdrive water pump pulley, p/n 11 51 1 706 781
    Best: Electric Water Pump (EWP)

    Air Con
    Not a ton to say here, other than that it adds lots more stress to your cooling system (so be warned) but yes, it is 100% possible. Use all the stock M20 components (including compressor). In order to bolt the M20 compressor up to the M30 compressor bracket, you’ll have to grind the bracket some to make clearance. It’s easy enough with a Dremel or bench grinder. See some of my threads in this forum for details

    Use an E28 535i radiator. Others may fit as well, but this seems to be the overwhelming consensus as it’s the thinnest. If your engine is particularly far back, you could probably get away with a thicker radiator that would improve the cooling efficiency of your fans.

    Component layout
    Make 100% sure that your expansion tank is the highest point in your cooling system and that the cold coolant fill level is higher than the bleed screw on the thermostat housing. Your radiator should be lower than both the expansion tank and thermo housing

    M30s are notoriously hard to bleed, and it’s usually because of component layout (see above). Ensure you’ve got that covered before starting bleeding or you’ll chase your tale forever. Once that’s done, they bleed just like an M20

    Details on fans:

    Details on component layout:

    Best way to bleed the m30 is nose up on ramps & use a high stack filler funnel,
    top the system up & leave 1-1.5lts of coolant in the funnel. Start the car turn the heater on & let the car get to temp
    Once the thermostat opens top the funnel back up try maintain 1lt+ in the funnel.
    As the car passes bubbles back through the funnel give the engine some mild revs this will help in the burping.

    after 10ish mins you shouldn’t be passing anymore bubbles, turn the car off, plug the funnel so you can recover the excess & fit you rad cap, you now have a burped m30 that shouldn’t overheat

    example of the funnel to use
    EPAuto-Radiator-Coolant-Filling-Funnel/dp/B01I40ZQWE/ref=asc_df_B01I40ZQWE/?tag=googleshopmob-22&linkCode=df0&hvadid=341774732830&hvpos=1o1&hvne tw=g&hvrand=12293821355490869403&hvpone=&hvptwo=&h vqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9072019 &hvtargid=pla-381147636217&psc=1


      Good idea for a sticky thread Corvallis!

      A couple of other tips:

      If you're happy running your fan at single speed, an e28 82 degree thermo switch also works well: P/N: 61 31 1 364 272 82. For the switch to get a better read on engine temps, put it in the thermostat housing rather than the side of the radiator. The S14 engine in the M3 is set up like this. There is a spare bung in the housing that is blanked off that the switch fits in to.

      The "hot climate" M30 came with a 71 degree thermostat. I have run one of these in tandem with the 82 degree thermo switch & 16 inch pusher fan on a stock e28 535i radiator with no overheating issues for 8 years in Australian heat (up to 46C / 115F).
      Running at the cooler temperature gives you slightly more headroom for the cooling system and reduces the chance of detonation in very hot weather.

      Weirdly with the troubles others report I've never had issues bleeding my M30 - procedure is the same as M20, so I guess I just got the component layout right to begin with.
      Last edited by lukeADE335i; 02-13-2020, 01:39 PM.
      My e30: OEM+ with M30B35