As you can tell from my posts I am no wiring guru. I have a car that is just killing me with strange issues. It is a late 60's GM car with external voltage regulator which went bad and shot up over 17 volts. Burned out my light bulbs and was the start of a low cranking voltage issue. Battery is brand new as is all wiring and ignition parts and all worked fine before verified with volt meter. Now car turns over like a top with zero hesitation, grind or grunt but goes from 12.85 volts down to 6.8-7volts under starter load ay starter bat cable lug. Starter works fine. I noticed that the strap that comes through the starter case and attached to the solenoid below the actual battery cable lug is bent and might be hitting case. It gets hot as a mother f'r after a crank or two. Should there be continuity between the "S", "R" or the strap and the case of the starter??? There appears to be approx 3-4 ohms of resistance but there is continuity? Could this be causing the excessive load? Could the 17 volts got it so hot that it melted the rubber bushing between it and the case inside? Bushing is still there. Problem is car will not start due to low voltage to coil and ignition. with res wire it gets as low as 4 volts while cranking. I am tempted to let it burn but for the sake of not going bankrupt any ideas?? Thanks
I don't believe the 17V "spike" was your issue (unless it actually got much higher). Race cars run 18V batteries on a regular basis with no ill effects. The strap would short to the case on crank if it were hitting...you'd know it! "S" term should show a resistance reading to ground (starter case) through the solenoid coil. "R" terminal should not. It only engages when the contact plate is pulled up against it by the solenoid (also engages starter). I believe this contact plate is dirty/worn/pitted. That would cause a poor connection to the starting motor (strap) on crank and could cause the heat problem. Would also account for the low voltage reading on "R" (you are running the wire from R up to coil + terminal, right?). I can tell you a bulletproof way to wire around it, but if you want to keep it original, you're going to have to find the bad connection in that starter.
It is normal for the starter to pull the battery/system voltage down to 8+ volts while cranking. The lower voltages you observed indicate some kind of problem. Check load test the battery's performance. It can charge up to a full 12 volts and still be weak. If the battery is ok look for a starter related problem. The connector strap you asked about can get hot. But if it's getting really hot either the starter is drawing too much current, or the connection on the strap is not good. If it turns out to be the second possibility that would not cause the starter to draw excess current.
Battery is brand new but I will have it load tested tomorrow. There is barely .3 of a voltage drop anywhere to the solenoid. I checked evey power source from battery, ignition switch, etc. Problem started right after voltage spike. I saw it on gauge and shut car off. It burnt out Petronix which was verified by them. I hate to pull the starter as it is an iron nose starter that spins like a hi torque mini starter with zero hesitation. I have relay to solenoid to help with hot start. The voltage dropped from 12.85 to 7.63 on cranking. I have to check amp draw when buddy helps me out. No res in line for tests incl factory wire. The strap actually looks like it bent or moved under heat as it is no longer perpincular to case but leaning. I bent a bit with screwdriver and now voltage is approx 9.67. I swapped back to points to get it going but It will not start at that voltage. I had checked when wiring was set up and it used to be in the 11.0-11.5 cranking voltage with the exact set up. The voltage spike happened the 1st time I started car with Petronix. I do have to say it ran great with set up and was able to lower idle and pull some timing. To be clear that strap becomes energized with full avail voltage when solenoid is activated? Can it be jumping to ground if too close to case. I have continuity from strap to case with zero power. There is resistance as noted above but it does have continuity. Should that be there?
Your continuity is coming from the motor windings... Remember, every circuit must have some path back to ground for current to flow, so you will have some continuity through any motor, relay coil, etc... No way that strap is hitting the case, IMO. With the amount of amps available when the solenoid kicks in, that piece of copper would have exploded if it was grounded to the case... When you say the voltage dropped, are you checking the battery cable pole, the starter motor strap, or the R terminal? How much voltage drop across the solenoid poles (batt cable to motor strap)? If the motor strap is "leaning", it sounds like the connecting screw was over tightened and bent it, OR the solenoid nose is somehow twisted in relation to the solenoid body/ starter motor. I've seen Chevy starters fail in just about every way imaginable (including sawing themselves in half), but I've never seen one of those straps soften and twist just from heat...
That strap carries the current through the starter armature, field coils and to ground so it will have continuity to ground. Try checking the voltage at the battery terminals while cranking the engine. The voltage shouldn't drop below 10.5 volts while cranking. When the voltage drops, it takes more current to turn the starter and that will heat up the starter strap. If the voltage stays up at the battery and is lower at the starter, you have battery cable issues. Either the cable or a connection is bad. Make certain you have big enough cables with the ground connected to the block. You should also have grounds connected to the body.
Bad or not big enough grounds are leading cause electrical gremlins. Clean all the grounding attaching points, check voltage drop again. My son bought a car and the guy that built it onlu had the ground to the frame- caused all sorts of problems. grounds to the block, frame, body, I actually go overboard and add extras and heavyer cables too.
Ok, I just moved from NY to CA and lost quite a bit of my tools in the move so I am working with bare min here. Car has rear mounted battery but wires are welding wire and grounded to chassis and again in front from engine to frame and frame to body. There is also a ground strap at the starter. Everything is new. I ck'd voltage and am happy that there is barely .2 drop across anything.Leading me to think starter or solenoid is drawing too much. It is 11.5 BBC but again had started with zero issues. Starter spins like a top with zero hesitation. I removed positive cable from starter and put a jumper between the start terminal at the starter and the + bat cable while checking amps when the solenoid activated. This is a new Sears clamp amp gauge that I am not familiar with and in all honestly I am not the greatest when it comes to electrical but I can get through most. The gauge @ 40 was out of limits. I moved to 400 and the gauge reads a draw of approx 71 amps. Again this is islotaing the solenoid. Is that a high draw? I understand that total starter draw should be approx 200amps? I appreciate the help here. Solenoid has heat shield but now looking back the car did just get up to temps and did not start when hot so I will assume the draw would be higher when hot? 70+ amps draw for just solenoid???
It would really help to see some pictures or drawings of what exactly you're doing. Also I haven't figured out what your complaint is. Does the starter work? Does the engine start? Does it have problems when it's hot? Is the problem that it won't spin the engine, or that the engine won't fire? Or are you just curious about how much current different parts of the starter draw?
It says right in the 1st post Car will not start due to not enough voltage to coil. Starter spins fine. Grounds are fine? What am I taking pic of? It is a standard Gm solenoid with a standard GM starter? There are only 3 wires and I explained above what I was testing? I appreciate help but posts have been fairly clear. I wante dto know what was drawing at starter and how to check. My question was how much of an amp draw would GM solenoid pull if it was OK. The problem was the solenoid was drawing over 70 amps. It was killing the voltage to start car. When it got hot it was apprx 4.5 volts going to coil to over ride the resitance wire voltage with full battery voltage. Bought new solenoid and now draw is 42.5-7 amps and voltage has shot up to over 11 volts avail from starter to coil. I have no idea why pertronix failed at the same time? I thought it was voltage spike.
I guess it's clear if you already know what it is you're trying to say, but from this end it's a bit confusing! sorry. The solenoid should have two windings in it, one that engages the starter drive, the other is a "hold" coil. The strong "engage" coil should be bypassed internally when the starter is cranking the engine.
No argument meant and I appreciate the help. Ok I do not want anybody looking back and seeing wrong numbers so after a long battle here it is. My solenoid was getting stuck on a heat shield tab which probably caused the orig 70 amp issue and then the 40 or so. It would hang up on tab that went passed solenoid body. Solenoid should pull under 20 amps activating solenoid but not turning starter. Starter without load is approx 150 amps or less complete with solenoid. Starter under my BBC load pulls 245 amps Lug that goes to points under start should read approx 11.5 volts I tried everything to get 12volts and I will say it is impossible without a 2nd external solenoid 1 for 12 v to activate and another for points or ignition. Thanks and just wanted to have correct info here. Why the Pertronix went at the same time is a mystery but I am running with points for now.
Batteries drop voltage when they are loaded, that's the way they are. Wires have resistance too. There's no need for 12v at the coil when cranking, coils are mostly all designed to run at about 8v. I wouldn't waste much time worrying about why the pertronix went out. Low budget non-oem electronic ignitions tend to do that.
Hopefully I haven't misread any of the posts above but when your running points, you also need to bypass the resistor during start mode. There should be a wire from the "R" terminal of the solonoid to the + side of the coil to accomplish this.
My Father the REALLY old time electrician allways told me "95% of electrical problems are bad connections" and he was right 99% of the time.
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