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    How can I check if a starter is bad?

    I had my battery tested at an auto parts store. They had me turn on the car, and keep the RPM at 2k for a minute. The guy said my battery was good, and my starter was going bad.

    My symptoms are slow start, and one time I had a click. But then it immediately started. The battery is 2.5 years old. A starter job on these cars is expensive. How can I validate that it is going bad?

    I have INPA, and a scanner. Is there anything I can use to validate the test before I go tearing the car apart to test / replace the starter?

    Call me skeptical, but they knew my battery was under warranty before the test.

    Thanks!

    #2
    I am confused why they had you turn the car on to test the battery. It's been awhile, but when I worked at a shop I swear the tester just hooked up the leads and would test it with the car off.

    If they had you turn the car on and rev it up, that would test the alternator.

    Unless the test they were also tested the alternator.

    I could be forgetting something, but I'd probably get a second opinion and test it somewhere else (another auto parts store).
    Build Thread:
    https://nam3forum.com/forums/forum/m...-new-pb-at-msr

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      #3
      Good info in this thread:

      I've gone through 3 starters in the last 3 years, about to order another one which makes 4. The first starter, unsure if it was original or not but was an OEM BMW, the car had ~115k miles, and randomly would not start if the car was warm. Kept turning the ignition key enough you'd get lucky and it would start normally. Always
      3.91 | CMP Subframe & RTAB Bushings | SMG (Relocated & Rebuilt) | ESS Gen 3 Supercharger | Redish | Beisan | GC Coilovers & ARCAs | Imola Interior | RE Rasp | RE Diablo | Storm Motorwerks Paddles | Will ZCPM3 Shift Knob | Apex ARC-8 19x9, 19x9.5 | Sony XAV-AX5000 | BAVSOUND | CSL & 255 SMG Upgrades | Tiag | Vert w/Hardtop

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        #4
        I replaced my starter recently, maybe 2 months ago. To test if it's going out, when the car is warm/hot, shut it down and try to restart. If it doesn't startup right away, that could be a symptom.

        If you DIY, starter job is not that terrible. I was dreading doing it, but after finding a couple of videos on Youtube with a walkthru, it wasn't nearly as bad as I thought. Would need to get some tools to reach 2 starter bolts easier, plus either needle nose pliers or special tool for throttle body boots (I kept the factory ones, they are not as bad to remove and put back on as I thought with the right tool).

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          #5
          Second auto parts store said battery needs to be charged, but is "good". I have a Battery Tender that allegedly reconditions AGM's, and I did that a month ago. Do y'all think I need a bigger charger to fully charge it? Or should the small one suffice?

          Thanks!

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            #6
            Get a multi-meter and measure voltage at the posts.
            3.91 | CMP Subframe & RTAB Bushings | SMG (Relocated & Rebuilt) | ESS Gen 3 Supercharger | Redish | Beisan | GC Coilovers & ARCAs | Imola Interior | RE Rasp | RE Diablo | Storm Motorwerks Paddles | Will ZCPM3 Shift Knob | Apex ARC-8 19x9, 19x9.5 | Sony XAV-AX5000 | BAVSOUND | CSL & 255 SMG Upgrades | Tiag | Vert w/Hardtop

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              #7
              Mine just up and died one morning when trying to go to work. I recall there were some signs (that I likely missed) like a slight change in cranking noise and slightly slower crank.

              Ended up replacing the starter myself with an OEM starter from Valeo (off of Rockauto). I had to buy a tool to reach the bolts but it was a pretty easy job (if you're used to removing the airbox).
              Last edited by zzyzx85; 01-13-2025, 01:51 PM.
              "your BMW has how many miles!?"

              2003 M3 coupe - Imolarot/Black 6 M/T - JRZ - Ground Control - Volk Racing - Karbonius - SuperSprint - Recaro - Schroth
              1989 325i sedan - track project coming soon!
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              ig: @zzyzx85

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                #8
                ^ This, taking off the intake plenum is not difficult. As an S54 owner, you definitely want to be familiar with how to remove it.

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                  #9
                  Originally posted by BRiley View Post
                  Second auto parts store said battery needs to be charged, but is "good". I have a Battery Tender that allegedly reconditions AGM's, and I did that a month ago. Do y'all think I need a bigger charger to fully charge it? Or should the small one suffice?

                  Thanks!
                  Forget those batt tenders. Buy this 10A charger for $25. https://www.amazon.com/YONHAN-Fully-...%2C203&sr=8-10

                  You might have low batt voltage due to bad alt or bad cable connection. Have the engine idling and measure the voltage DIRECTLY ON THE BATT POSTS, not on the cable terminals. It should be close to 14v. Below 13.7v is questionable. Once this test passed, measure batt with engine off and it should be 12.5v or higher. Then measure the voltage from front jumper post to vanos body while cranking, the voltage should be higher than 10v with the starter cranking strong.

                  Comment


                    #10
                    Originally posted by sapote View Post

                    Forget those batt tenders. Buy this 10A charger for $25.
                    \.
                    Borrowed one from a neighbor, and it showed 12.1 volts. It's reconditioning now. Hopefully that'll do it. Thanks all for the advice!

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                      #11
                      Originally posted by BRiley View Post

                      Borrowed one from a neighbor, and it showed 12.1 volts. It's reconditioning now. Hopefully that'll do it. Thanks all for the advice!
                      12.1v with engine idling? Yes then bad alt regulator or worn brushes.

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                        #12
                        In my case the starter would spin but the gear wouldn't “pop” to make contact with the flywheel. Replaced around 120k mi IIRC.
                        Last edited by JokerElite; 01-14-2025, 03:26 PM.

                        Comment


                          #13
                          Originally posted by BRiley View Post
                          I had my battery tested at an auto parts store. They had me turn on the car, and keep the RPM at 2k for a minute. The guy said my battery was good, and my starter was going bad.

                          My symptoms are slow start, and one time I had a click. But then it immediately started. The battery is 2.5 years old. A starter job on these cars is expensive. How can I validate that it is going bad?

                          I have INPA, and a scanner. Is there anything I can use to validate the test before I go tearing the car apart to test / replace the starter?

                          Call me skeptical, but they knew my battery was under warranty before the test.

                          Thanks!
                          A dodgy earth can sometime cause a slow engine turn over. The earth strap is hard to get to. So to test you can take a jump start lead and link from an earth point the bulkhead to the engine hook near te thermostat. If it improves the turn over speed engine earth strap and its connector will need cleaning up.

                          Comment


                            #14
                            There's no really way to test a solenoid. Either its bad or it isn't.

                            The starter motor itself is a mechanical part. There's wear but it also fills up with oil caked up with clutch material.

                            I can't think of another test that would tell you anything outside of a load test. If it is exceptionally high then the motor is on its way out.

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