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How to: Replace M20 Starter easy!

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    How to: Replace M20 Starter easy!

    How to replace your m20 starter pain-free!

    A D.I.Y. for the complete Newbie!

    First, we’ll start with the symptoms of a starter going out. For me, I noticed whenever I would stop to get gas on a road trip, or stopped by a store, my car wouldn’t turn on. It almost always happened when the car was warm after use, and never really gave me a problem when I hadn’t used it for a while. I would put in the key, all the lights would come on, but nothing. No cranking, no noise, nothing. It couldn’t have been the fuel pump, which I replaced new, or the battery, which was a couple months old. I had literally replaced almost every piece of my car responsible for getting my car up and running.

    Below is a link to a Pelican parts Article on checking if your starter is actually to blame.

    Where to buy?

    When it comes to any part on a car that is vital to it’s use, I find it’s always best to find a vendor nearby. Living on the West Coast, I had a couple to choose from including and I chose autohausaz, since it was cheaper than pelican-parts and had similar fast shipping. You can buy used if you want, since they’re easy enough to replace. Keep in mind all late model e30 m20 engines (Be it 325i or ix) work with one another. There are two different kinds, a larger one (early model) and smaller one (late model), although from my research both would work. Double check that though.

    Preliminary Tasks

    Tools Needed:
    Jackstands (2-4)
    ½ inch ratchet and various sockets
    ¾ inch ratchet and various sockets*
    Extensions for ½ ratchet
    U-joint for ½ ratchet (1 needed, 2 or more makes things easier)
    Electrical tape
    Flat head
    Various open wrenches (8mm, 10mm, 12mm, 13mm, 15mm, 16mm)
    Beer (If you’re of drinking age)

    First things first, get your car in a secure area, preferably in a garage since you’re going to spend some time beneath the car. Make sure you have your tools ahead of time, some refreshments, and a helper wouldn’t hurt (not necessary however.)

    Step 1: Jack up the car.

    Easy enough right? Well some e30 owners are young kids, working on their cars for the first time so I felt I should include this. If this is your first time jacking up a car, you should have a helper present or someone to show you how to do it. Below is a picture of e30 jacking points:

    Also, make sure you block of the rear wheels, you only need the front two in the air.
    (Make sure your emergency brake is on)

    Step 2: Disconnect the Battery

    After you have safely lifted the front of your car at a height safe and comfortable enough for you to be under, open your trunk to disconnect your battery. Remember to ALWAYS DISCONNECT THE NEGATIVE FIRST, or else you will die and so will your mother. Use a 10mm open wrench for this turning counter-clockwise (remember: left loosey righty tighty!). Now move the cable out of the way completely so it won’t touch anything metal. Now remove the positive, which I believe you can use a 13mm open wrench. Once you have both disconnected, move them completely out of the way and separate from each other.

    Congrats, you’re halfway there.

    Step 3: Remove the airbox!*

    This step is only necessary if you only have one u-joint like I did*. Loosen the clamp on the intake boot with the flat head, not remove the nuts that hold the airbox in with a 10mm socket. Carefully pull it out, and make sure not top rip the intake boot, or anything else for that matter!

    WTT: 1989 325i w/ many mods for stock e28. Pm me if interested.

    starter install...

    where is the rest of the DIY?....
    I love sitting down and just driving!


      Step 4: Removing the top nut!

      It’s the one everyone talks about. The one that keeps us all up at night! This bolt/nut combo is a headache for most people, claiming top spot as most hated object to remove from the e30! But never fear, you have a D.I.Y. and some common sense! You’ll have this thing out in no time! This is where you make your special tool. Using your ½ ratchet, connect enough extensions to be able to reach this nut, and at the of those extensions place a u-joint with a 16mm socket attached to it. This should be angled so you can place the socket right on the nut.

      *If you have 2 u-joints, using your common sense weapon create the same tool as above only allow for a greater “entering” angle.

      Now, simply give the ratchet a turn or two (just enough to loosen it).
      Once this step is done, pat yourself on the back, the hard part is over with. Standing on the side of the car, reach in and undo the nut by hand, you should be able to reach it moving those pesky hoses by hand. This is where a helper would come in handy to hold the bolt in place from underneath with a finger or two while you completely remove the nut by hand (However, it’s easy enough to remove the nut by hand). Now “tap” the bolt lightly, only enough to move it in towards the trans.

      Step 5: Removing wires attached to the starter.

      I forgot, but you should be able to easily tell which sockets and/or open wrenches you’ll need to remove the nuts that old them to the starter. Please take a picture, make a diagram, or visually memorize what orientation the wires are in. Although from my research you won’t cause harm if you have them wrong, you’ll be doing this all over again if you do. From memory: The bigger black and red wire are held down by the same nut, which was 12mm if I remember correctly. The black one is closer to the starter, while the red is above it. Another smaller wire is also attached to the red one, which is held by a 10mm nut. Finally, the smallest one which is held by an 8mm nut, is on the other side. When putting these back together, make sure you put them back the same way, it shouldn’t be hard to tell which goes where because the smaller two are individually sized. There should be a total of 4 wires attached for the late model m20 starter. I have read the earlier only had 3?

      Step 6: Complete Starter removal.

      Now we go for the grand tamale. You should have already disconnected the top nut, pushed the bolt almost out, and disconnected the wires/cables the connect to the starter.

      Now go underneath the car, bringing the ½ ratchet along with size 10mm, 12mm, and 16mm sockets. Also, bring an open wrench in size 16mm, 12mm, and 10mm. You should clearly see the only nut/bolt holding the starter. Undo the 16mm nut until it can be loosened by hand. Use the ½ ratchet with the appropriate size to hold the bolt on the other side to keep it from moving along with the nut. Note: You do not want to undo this from the “bolt side” in case you strip the reverse torx nut, just hold it in place. Once this is done completely remove the bolt and nut. Now push the starter towards the radiator a bit, just enough to get it free from the top bolt. The starter is now out, there is enough space from below to remove.

      *Also, don’t take the top bolt out completely, while this is not a big issue just make things easier on yourself and leave it in.

      Installation is the opposite of removal.

      Installation tips:
      When putting the new starter in, start with placing the top bolt in first and have someone tighten the nut onto the bolt by hand. Once this is done place the other bolt and nut onto the starter. Tighten the bottom nut as much as you can (Not enough the break it, just so it won’t move), and then using your special tool tighten the top nut. Make sure the starter doesn’t move. Now reconnect the wires/cables in their correct manner, tighten them with the appropriate nuts, and voila you’re done!

      **When reconnecting the battery, connect the positive first, then the negative (Remember, you will die if you don’t do this. Slow and painfully)

      See it wasn’t so bad was it? Easy as pie! Just remember that top bolt is the hardest to get to when removing the transmission, so this way will make things easier when doing that job. And of course, I am not responsible if you hurt yourself, others, or cause damage to anything. Follow this at your own risk.
      WTT: 1989 325i w/ many mods for stock e28. Pm me if interested.


        Originally posted by JRKOUPE View Post
        where is the rest of the DIY?....

        Had to wait for approval
        WTT: 1989 325i w/ many mods for stock e28. Pm me if interested.


          good write up! I also just put in a new starter this weekend, and im curious as to what tool you used to hold the head of the reverse torx, while turning the nut loose


            Originally posted by bzboardz View Post
            good write up! I also just put in a new starter this weekend, and im curious as to what tool you used to hold the head of the reverse torx, while turning the nut loose
            Reverse torx socket, of course :D

            They are available at Harbor Freight tools, package of 5 includes all the ones you need for your BMW, last I saw they were $9.99.

            If you are daring, you can use an 11mm socket and a hammer to get it on.
            Transaction feedback: Here, here and here. Thanks :D


              You don't need the torx. Just use a hex socket, but just use it to hold it in place not to remove it or you'll strip it.
              WTT: 1989 325i w/ many mods for stock e28. Pm me if interested.


                The nut on the starter side loosens up easy enough, you just need to get the bolt side to stay in place without applying much if any pressure to it.
                WTT: 1989 325i w/ many mods for stock e28. Pm me if interested.


                  yea your right. I was only working from the top and couldn't hold both so I just put some JB weld on the head to hold it in place


                    Just for you information I use Astro Pneumatic (AP 7114) 4 Piece Double Flexible Torx Wrench Set, which was a life saver.


                      Just replaced mine,
                      17mm socket top and bottom, straight socket -> extension
                      I did however need to be reasonably flexible with the arms to hold things in place while tightening it back up again.

                      Didn't need to take anything else off, although this is a NZ / right hand drive car, so various things were probably not in the way that could have been.

                      Total time for swap 45min give or take.


                        for us US spec boys and girls:

                        i pulled the intake manifold to do the starter. it takes 30 minutes to get the manifold on and off(but ive pulled alot of them). then from that point it takes another 30 to pull and replace the starter
                        My feedback:





                          Just did this right now. Didn't have to remove anything. Jammed a prybar into the first nut to hold it in place and I had to do some contorting to get the next one. slipped it out through the bottom and replaced it the same way. It did require two people though.

                          That is another thing I've done that I never did before. These cars are pretty easy to work on.


                            So all the starters I've pulled and installed on my e30s have been a complete bitch. For that top fastener, I have to use unusually thin walled sockets to clear the knuckle on the block. The nut is usually so tight that I have to use a 1/2in impact to break it loose. Once it's loose I have to use a flex head wrench squeezed between the firewall and the bell housing lip to keep the bolt from spinning. I have to use the flex head because there is no room for the above mentioned pry bar or socket. There can't be more than a couple of centimeters. Surely, the two 87's and one 88' on which I've done starters don't have unique firewall clearances. This has got to be my least favorite e30 project.

                            91' 318i


                              Nice enough write-up, but it doesn't make the process any easier. It's still a total PITA, so I don't quite understand the title.

                              I've actually found it easier to just unbolt the two engine/transmission mount bolts and jack the engine up from the oil pan and shift it forward. That provides clearance to the bolts. Once I've taken one out once, I always put the starter bolts back in the other way, as I find it easier to to have the nut on the front side and the bolt on the rear.