Repeat starter failure
As this is my first post here forgive me and please ask questions if i'm not clear on anything. As the title says I have had and have at this moment a Ford with repeat starter failure. I have but 3 different starters in this thing and they all come back with in a couple weeks to a month time. All 3 different brands with the last being motorcraft from Ford. How I verified the starter being bad is with my snap on verus pro scope. When it doesn't start I have good 12.3 volts at the start + cable and at the solenoid wire. Also I'm reading 30-35 amps on the starter solenoid when it doesn't start. When it does start I am getting 10.8 volts at starter + post and same on solenoid wire. Amperage draw is 10 amps. The vehicle drives great with no mechanical noise or any other known issues other then an manifold leak on the passenger side. Thank you for reading and any in site as to why this is a common thing on fords for me at least.
It sounds like the Solenoid contacts are an issue, have you verified the power out of the solenoid on the braided cable into the motor?? 10 amps cranking seems very low
But it cranks & starts fine with that amperage. When it doesn't start it is pulling 30-35 amps on the starter solenoid wire.
10 amp reading must be on the solenoid wire. I was thinking you were testing the main B+ at the starter and got 10 amps. Checking for power out of the solenoid (braided cable) during the concern will let you know if its a solenoid not working or internal issue in the starter motor. I have not seen very many intermittent voltage drop issues that would be be a no operation fault in a high current
I will check that solenoid braided wire. . Sorry for the confusion. I should of done screen capture of my readings instead of writing them down. If you try craning several times the vehicle will eventually crank and start without any problems. But when to problem occurs its a no crank no start condition.
Are these quality starters with no fluid contamination?
I thought it was that too but the one that is in it now is a ford motor craft from the ford dealer. Their isn't any oil leaking near the starter. I had the same problem on another ford 6-12 months ago and we just kept putting starter in it till it was fixed or at least for now. Only reason I know he hasn't had any issues was cause he is a normal customer of mine and said he hasn't had any
voltage drop on the cables sorry for the limited response but my stars are not currently aligned....
I would say the same but I have 12.3 volts when the vehicle doesn't start at the starter wires.
I will agree with voltage dropping both the positive battery cable from starter post to battery positive, solenoid energizer wire post on starter to battery positive and the starter case to battery negative, while in the no crank condition, and when cranking normally, if possible. It's fast, easy and quickly rules something out. The 10 amps cranking number you talk of is likely the starter
Randall, I would agree with your comments on the solenoid current draw, pull in versus hold in. That being said, if the voltage drop tests don't reveal any problems then it needs yet another starter. Also, I believe that if he's getting 30-35 amps flowing through the solenoid, then there probably is no voltage drop bad enough to keep the starter from turning. Or at least trying to crank.
Questions welcome! Performing a voltage drop test on the power and ground sides of the starter will identify the high resistance in the starter circuit I believe is causing the premature failure. There are several resources on the net that will explain the process, the main thing to remember is the meter is showing what is lost between the source and destination, use the 20 volt scale on the
Take one lead to bat neg the other to the case of the starter. When it does not start what is the reading?
Is it hot or cold or just intermittent? 30 amp on exciter wire only proves sufficient power and ground for solenoid and maybe not starter also as suggested test grounds and powers for voltage drop during failure.
Random from what I can tell. It is 3-20 degrees here which is normal for Alaska. But when I duplicate the concern it is 50 degrees in the garage.
Quick info update. When I checked my voltages at the starter I was connected to the starter ground and not the battery negative. Also the key is held in the start position by my handy helper. I don't have problem doing a voltage drop test for my battery to the starter, but I just don't understand how that would be an issue when i get 12.3 volts on both starter starter cable and solenoid wire…
Having 10+V at the stater (measured between the stud and the case) while it is cranking positively means that there is NOT an excessive voltage drop between the battery and the starter, as regards the main power and ground, when tested. However, there is a slight chance that there is a problem in the control (solenoid feed) circuit, or an intermittent fault on any circuit. If the control
Phillip, is the starter a 10.8 V starter or a 12V starter? Silly question right? The voltage drop test may reveal a low voltage during run time that leads to low RPM, overheat and other issues that cook the inside of motors, fuel pumps etc. it would appear you have a 1.5 V drop on the positive side cable while cranking, where .3V would be my limit on a cable we have 1.5V . If I am reading you
What single automotive battery maintains 12.4V while cranking a V8 engine which has normal compression? What leads you to believe that this vehicle has such a battery?
Marlin, What is your acceptable voltage drop on a positive cable?
It depends. Why didn't you answer my question?
I thought it was rhetorical. Here is a published and industry accepted document you can review. Testing is the baseline for for diagnosis, it keeps us from throwing parts at a failure. ELECTRICAL CHECKS ON THE STARTER CIRCUIT To check the starter circuit for excessive resistance, you need to measure the voltage drop at the battery, battery cable connections and starter while the engine is
It was not rhetorical, and it seems to me that the reason for my asking is apparent. Once you answer it, I will know how to proceed. The testing sequence which you presented is pathetic, because it doesn't address the possibility of low battery voltage while cranking. The excellence of most of it is completely negated because of this. You are welcome to ignore these comments and just address my
Marlin, I believe you misunderstood me. My original reply was addressed to Phillip. when he wrote, " I just don't understand how that would be an issue when i get 12.3 volts on both starter starter cable and solenoid wire. With the solenoid pulling 30-35 amps with the no crank condition". about my voltage drop suggestion. The measurement Phillip posted was not while cranking and therefore was
You wrote "it would appear you have a 1.5 V drop on the positive side cable while cranking". He said that the voltage in this condition (cranking) is 10.8V between the starter's terminal and case. Adding 1.5V drop (per your statement), plus .1V for ground side voltage drop (my figure), results in battery voltage of 12.4V while cranking. I wonder why you think this is the case, or could even
What kind of lead is on the S terminal? I've seen several of these with the push on lead have issues with connections. Most starters will have you change to the bolt on type. I can't remember which type originally came on this vehicle. I suspect it already has the screw on type. But it's been a while since I've done a 2008.
Nothing has been modified from memory. Vehicle isn't near me it is about a 20 minute drive away waiting form me to get a back to it. Originally the ford trucks to my knowledge or at least all the ones I have every dealt with have a bolt on style and not a connector style.
You need to voltage drop test the starter ground. Perform your voltage drop test from starter case/ground stud to the battery negative and see what voltage is when the no-start is occuring, during a crank attempt. If you're measuring the voltage drop using the starter ground, then this could potentially be your issue as to why the voltage drops all appear good. That is where I'd start. Hope that
Is the exhast leaking on the starter?
Their is actually.
You say you have 12.3 on B+ during the no start....How about on the stud B+ attaches to on the starter. Power flow = cable to stud. I have seen fords where that cable end got corroded (black color) and needs to be shined up. Just a thought. Hopefully I didn't miss a response, but did you check on the braided wire during no crank?
any chance a heat shield is missing? Can you compare to another "same" vehicle?
No heat shield on the starter originally but it does have the cable covers still. The exhaust has it's shields.
One question to clarify, when the starter fails to crank does it produce a single click each time you try to start it? There are two different windings used in the solenoid, one called a pull-in winding and the other called a hold-in winding. When the ignition switch is placed in the START position, voltage is applied to the S terminal of the solenoid. The hold-in winding has its own ground to
I did take a look at the flex plate before I put the last starter in cause one of their complaints was a metal to metal sound when cranking. But I didn't see any damage to the flex plate teeth.
Did you test/inspect the old starters after removing them?
I never really inspected them outside the vehicle other than a visual and i didn't really see anything. I just seen to many starters work fine with no load and then don't do crap when trying to turn an engine.
I just wanted to update and hope I'm doing this right. I went out to try and reproduce the problem so i could get the the voltage/amperage checks and post them, but after trying for a few hours I couldn't get the vehicle to act up. The customer said for the last couple days it was fine also. Fortunately they are a family friend and have only ever allowed me to work on their vehicles. So I know