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M42 Overheating...another one

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    M42 Overheating...another one

    The issue was solved, it was the fan clutch Bought a new one and that one failed the newspaper test as well. Double check your new parts!

    Let me lay some background. I bought the car around the beginning of May and drove it across Canada back home. For most of the trip I never noticed any overheating issues until the last day when it started to go up to 3/4. Since then it was in the shop to get up to safety and it went up to 3/4 once in the last week then finally yesterday it was going into the tip of the red.

    Now for the technical:
    - The heater blows hot when on
    - If I turn the heater off and leave the vents open while driving I'll get hot air inside the car and notice it help cool down the engine a little
    - I have been doing this for now to keep the temp near the middle (5/8)

    - It seems to be fine at idle
    - Overheating happens when driving the car
    - Get the car moving when it's already hot will briefly drop the temp as the air flows over it

    - My coolant fluid level seems to be stable haven't notice any loss or leaks left behind by the car

    - I also noticed sometimes the it would overheat then suddenly drop down to temp. It looks like the fan clutch was on it's way out
    Last edited by onesecond; 06-12-2019, 12:27 PM. Reason: solved

    #2
    I would wager to say its the fan clutch, especially if its the original one. try spinning it around by hand when the car is off. Also you might want to have a look at the thermostat. Could be stuck closed if you are overheating while moving. hopefully that helps!

    Comment


      #3
      Overheating while moving but not at idle is a symptom of bad airflow or coolant flow through the radiator, or if it is consuming coolant a blown head gasket or cracked head. Inspect and clean the airflow path through the condenser and radiator, flush the cooling system, especially the radiator, with it out of the car. Avoid driving it until you have fixed the problem, M42 heads are very easy to crack through overheating.
      @turbovarg
      '91 318is, M20B25, T3/T04E 60 trim (15psi), megasquirt, coilovers, Z3 rack, cold AC
      [b u i l d]
      [Car of the month: April 2018]

      0c8b7c9527af628a346878feb14bf757

      Comment


        #4
        Also just to make sure, the blower won't blow hot until the engine is on correct?

        Comment


          #5
          For less than $200, you can refresh your cooling system. You can buy a new Radiator, Water pump, Thermostat, and Lower/Upper radiator hoses. I suggest you do this. I did this to my car, and it was a 1 owner 95k mile 318i.

          Sent from my Pixel 3 using Tapatalk
          '91 318i (Alpine) - daily
          '88 325ix (Zinno) - drive here and there!

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            #6
            Tighten the ground nut on the back of the temp gauge on the cluster to ensure you are getting an accurate temp reading before proceeding.

            -NICK

            Comment


              #7
              Ground seems to be fine as the needle isn't jumping at all. It'll climb slowly as the engine warms up then overtime move up in the range. I ordered odometer gears which should be in this week and will double check when I have the cluster out then

              For the cooling kit I'm assuming you're talking about the Turner one?

              Comment


                #8
                Originally posted by onesecond View Post
                Ground seems to be fine as the needle isn't jumping at all. It'll climb slowly as the engine warms up then overtime move up in the range. I ordered odometer gears which should be in this week and will double check when I have the cluster out then



                For the cooling kit I'm assuming you're talking about the Turner one?
                I buy parts through FCP euro and or Amazon.

                Sent from my Pixel 3 using Tapatalk
                '91 318i (Alpine) - daily
                '88 325ix (Zinno) - drive here and there!

                Comment


                  #9
                  So when looking under the hood earlier today I noticed some exposed wire near the temp sensor in the radiator. This led me down the road and I think I have found the culprit, the auxiliary fan.

                  I found that fuse 18 was blown so I replaced that today but sadly it blew again. I also tried the wire trick on the temp sensor connection and the fan does not turn on at all!

                  I was driving around town today (I know, I know) but it rarely went above the midway on the temp and if it did it was only slightly over.

                  Now anyone know what may be causing the fan not to turn on at all and blowing the fuse?

                  Comment


                    #10
                    A blowing fuse could be a failure in the fan, or a short somewhere in the wiring harness. Honestly, the aux fan should not even be necessary to keep the engine at the right temperature. I ripped out the condenser and everything a decade ago. While you have found an issue, it is not likely to be the issue causing your overheating. As others noted, there is either a blockage in the cooling system, a dead thermostat or a dead main fan clutch.

                    Comment


                      #11
                      Ahh brought down to reality, as you called it, it's the fan clutch. Did a magazine/newspaper test this morning and it brought it to a halt. It still spins and will slightly speed up but I guess when it gets really hot, not fast enough.

                      Now for the part, there seems to be a ton of options with a wide range in price. Is this a stick to OEM or are the other parts ok to use? BEHR, Sachs?

                      Comment


                        #12
                        https://www.fcpeuro.com/products/bmw...tch-3141152101

                        Sent from my Pixel 3 using Tapatalk
                        '91 318i (Alpine) - daily
                        '88 325ix (Zinno) - drive here and there!

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                          #13
                          https://germanparts.ca/parts/bmw/199...r-fan-hardware ?

                          After shipping, brokerage fees and conversion this would still be cheaper :(

                          Comment


                            #14
                            Also look on Amazon and eBay.

                            Sent from my Pixel 3 using Tapatalk
                            '91 318i (Alpine) - daily
                            '88 325ix (Zinno) - drive here and there!

                            Comment


                              #15
                              One more thing before I make an order. The radiator temperature switch doesn't control the fan clutch does it? Just the aux fan?

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